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6.09k
| versions
list | update_date
timestamp[s] | authors_parsed
list |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
quant-ph/0603137
|
Tobias J. Osborne
|
Tobias J. Osborne
|
The ground state of a class of noncritical 1D quantum spin systems can
be approximated efficiently
|
9 pages, 1 eps figure, minor changes
|
Phys. Rev. A 75, 042306 (2007)
|
10.1103/PhysRevA.75.042306
| null |
quant-ph
| null |
We study families H_n of 1D quantum spin systems, where n is the number of
spins, which have a spectral gap \Delta E between the ground-state and
first-excited state energy that scales, asymptotically, as a constant in n. We
show that if the ground state |\Omega_m> of the hamiltonian H_m on m spins,
where m is an O(1) constant, is locally the same as the ground state
|\Omega_n>, for arbitrarily large n, then an arbitrarily good approximation to
the ground state of H_n can be stored efficiently for all n. We formulate a
conjecture that, if true, would imply our result applies to all noncritical 1D
spin systems. We also include an appendix on quasi-adiabatic evolutions.
|
[
{
"version": "v1",
"created": "Wed, 15 Mar 2006 15:31:43 GMT"
},
{
"version": "v2",
"created": "Thu, 1 Mar 2007 10:45:56 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Osborne",
"Tobias J.",
""
]
] |
quant-ph/0603138
|
Markus A. Cirone
|
E. Charron, M. A. Cirone, A. Negretti, J. Schmiedmayer, T. Calarco
|
Theoretical analysis of the implementation of a quantum phase gate with
neutral atoms on atom chips
|
9 pages, 5 color figures
|
Phys. Rev. A 74, 012308 (2006)
|
10.1103/PhysRevA.74.012308
| null |
quant-ph
| null |
We present a detailed, realistic analysis of the implementation of a proposal
for a quantum phase gate based on atomic vibrational states, specializing it to
neutral rubidium atoms on atom chips. We show how to create a double--well
potential with static currents on the atom chips, using for all relevant
parameters values that are achieved with present technology. The potential
barrier between the two wells can be modified by varying the currents in order
to realize a quantum phase gate for qubit states encoded in the atomic external
degree of freedom. The gate performance is analyzed through numerical
simulations; the operation time is ~10 ms with a performance fidelity above
99.9%. For storage of the state between the operations the qubit state can be
transferred efficiently via Raman transitions to two hyperfine states, where
its decoherence is strongly inhibited. In addition we discuss the limits
imposed by the proximity of the surface to the gate fidelity.
|
[
{
"version": "v1",
"created": "Wed, 15 Mar 2006 15:59:49 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Charron",
"E.",
""
],
[
"Cirone",
"M. A.",
""
],
[
"Negretti",
"A.",
""
],
[
"Schmiedmayer",
"J.",
""
],
[
"Calarco",
"T.",
""
]
] |
quant-ph/0603139
|
Mohamad Ali Jafarizadeh
|
M. A. Jafarizadeh, S. Salimi
|
Investigation of Continuous-Time Quantum Walk Via Modules of Bose-Mesner
and Terwilliger Algebras
|
44 pages, 4 figures
| null |
10.1088/0305-4470/39/42/007
| null |
quant-ph
| null |
The continuous-time quantum walk on the underlying graphs of association
schemes have been studied, via the algebraic combinatorics structures of
association schemes, namely semi-simple modules of their Bose-Mesner and
(reference state dependent) Terwilliger algebras. By choosing the (walk)
starting site as a reference state, the Terwilliger algebra connected with this
choice turns the graph into the metric space, hence stratifies the graph into a
(d+1) disjoint union of strata, where the amplitudes of observing the
continuous-time quantum walk on all sites belonging to a given stratum are the
same. In graphs of association schemes with known spectrum, the transition
amplitudes and average probabilities are given in terms of dual eigenvalues of
association schemes. As most of association schemes arise from finite groups,
hence the continuous-time walk on generic group association schemes have been
studied in great details, where the transition amplitudes are given in terms of
characters of groups. Further investigated examples are the walk on graphs of
association schemes of symmetric $S_n$, Dihedral $D_{2m}$ and cyclic groups.
Also, following Ref.\cite{js}, the spectral distributions connected to the
highest irreducible representations of Terwilliger algebras of some rather
important graphs, namely distance regular graphs, have been presented. Then
using spectral distribution, the amplitudes of continuous-time quantum walk on
graphs such as cycle graph $C_n$, Johnson and normal subgroup graphs have been
evaluated. {\bf Keywords: Continuous-time quantum walk, Association scheme,
Bose-Mesner algebra, Terwilliger algebra, Spectral distribution, Distance
regular graph.} {\bf PACs Index: 03.65.Ud}
|
[
{
"version": "v1",
"created": "Wed, 15 Mar 2006 16:08:42 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Jafarizadeh",
"M. A.",
""
],
[
"Salimi",
"S.",
""
]
] |
quant-ph/0603140
|
Samuel J. Lomonaco jr
|
Samuel J. Lomonaco, Jr. and Louis H. Kauffman
|
Is Grover's Algorithm a Quantum Hidden Subgroup Algorithm ?
| null | null | null | null |
quant-ph
| null |
The arguments given in this paper suggest that Grover's and Shor's algorithms
are more closely related than one might at first expect. Specifically, we show
that Grover's algorithm can be viewed as a quantum algorithm which solves a
non-abelian hidden subgroup problem (HSP). But we then go on to show that the
standard non-abelian quantum hidden subgroup (QHS) algorithm can not find a
solution to this particular HSP.
This leaves open the question as to whether or not there is some modification
of the standard non-abelian QHS algorithm which is equivalent to Grover's
algorithm.
|
[
{
"version": "v1",
"created": "Wed, 15 Mar 2006 19:30:29 GMT"
}
] | 2012-08-27T00:00:00 |
[
[
"Lomonaco,",
"Samuel J.",
"Jr."
],
[
"Kauffman",
"Louis H.",
""
]
] |
quant-ph/0603141
|
Bryan C. Jacobs
|
B.C. Jacobs, T.B. Pittman, and J.D. Franson
|
Single Photon Source Using Laser Pulses and Two-Photon Absorption
| null | null |
10.1103/PhysRevA.74.010303
| null |
quant-ph
| null |
We have previously shown that two-photon absorption (TPA) and the quantum
Zeno effect can be used to make deterministic quantum logic devices from an
otherwise linear optical system. Here we show that this type of quantum Zeno
gate can be used with additional two-photon absorbing media and weak laser
pulses to make a heralded single photon source. A source of this kind is
expected to have a number of practical advantages that make it well suited for
large scale quantum information processing applications.
|
[
{
"version": "v1",
"created": "Wed, 15 Mar 2006 22:23:28 GMT"
},
{
"version": "v2",
"created": "Fri, 17 Mar 2006 23:19:54 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Jacobs",
"B. C.",
""
],
[
"Pittman",
"T. B.",
""
],
[
"Franson",
"J. D.",
""
]
] |
quant-ph/0603142
|
Robert Clark
|
Kenneth R. Brown, Robert J. Clark, Jaroslaw Labaziewicz, Philip
Richerme, David R. Leibrandt, and Isaac L. Chuang
|
Electron impact ionization loading of a surface electrode ion trap
|
4 pages, 5 eps figures. Shift in focus, minor corrections
| null |
10.1103/PhysRevA.75.015401
| null |
quant-ph
| null |
We demonstrate a method for loading surface electrode ion traps by electron
impact ionization. The method relies on the property of surface electrode
geometries that the trap depth can be increased at the cost of more
micromotion. By introducing a buffer gas, we can counteract the rf heating
assocated with the micromotion and benefit from the larger trap depth. After an
initial loading of the trap, standard compensation techniques can be used to
cancel the stray fields resulting from charged dielectric and allow for the
loading of the trap at ultra-high vacuum.
|
[
{
"version": "v1",
"created": "Thu, 16 Mar 2006 00:34:34 GMT"
},
{
"version": "v2",
"created": "Thu, 16 Mar 2006 22:26:55 GMT"
},
{
"version": "v3",
"created": "Fri, 21 Apr 2006 00:55:14 GMT"
},
{
"version": "v4",
"created": "Thu, 29 Jun 2006 16:46:52 GMT"
}
] | 2013-05-29T00:00:00 |
[
[
"Brown",
"Kenneth R.",
""
],
[
"Clark",
"Robert J.",
""
],
[
"Labaziewicz",
"Jaroslaw",
""
],
[
"Richerme",
"Philip",
""
],
[
"Leibrandt",
"David R.",
""
],
[
"Chuang",
"Isaac L.",
""
]
] |
quant-ph/0603143
|
Hoshang Heydari
|
Hoshang Heydari
|
Generating set for general multipartite entangled states
|
5 pages
|
Proceedings of the 8th International Conference on Quantum
Communication, Measurement and Computing, Edited by O. Hirota, J. H. Shapiro,
and M. Sasaki, (NICT Press, Japan, 2007), pp.311-314
| null | null |
quant-ph
| null |
We propose a entanglement generating set for a general multipartite state
based on the of concurrence. In particular, we show that concurrence for
general multipartite states can be constructed by different classes of local
operators which are defined by complement of positive operator valued measure
on quantum phases. The entanglement generating set consists of different
classes of entanglement that are detected by these classes of operators and
contributes to the degree of entanglement for a general multipartite state.
|
[
{
"version": "v1",
"created": "Thu, 16 Mar 2006 05:29:26 GMT"
},
{
"version": "v2",
"created": "Wed, 22 Aug 2007 08:52:16 GMT"
}
] | 2007-08-22T00:00:00 |
[
[
"Heydari",
"Hoshang",
""
]
] |
quant-ph/0603144
|
Jian Wang
|
Jian Wang, Quan Zhang, Chao-jing Tang
|
Quantum secure communication scheme with W state
|
Comments are welcome
|
Commun. Theor. Phys., 2007, 48(4):637-640
|
10.1088/0253-6102/48/4/013
| null |
quant-ph
| null |
Recently, Cao et al. proposed a new quantum secure direct communication
scheme using W state. In their scheme, the error rate introduced by an
eavesdropper who takes intercept-resend attack, is only 8.3%. Actually, their
scheme is just a quantum key distribution scheme because the communication
parties first create a shared key and then encrypt the secret message using
one-time pad. We then present a quantum secure communication scheme using
three-qubit W state. In our scheme, the error rate is raised to 25% and it is
not necessary for the present scheme to use alternative measurement or Bell
basis measurement. We also show our scheme is unconditionally secure.
|
[
{
"version": "v1",
"created": "Thu, 16 Mar 2006 08:01:59 GMT"
}
] | 2015-06-26T00:00:00 |
[
[
"Wang",
"Jian",
""
],
[
"Zhang",
"Quan",
""
],
[
"Tang",
"Chao-jing",
""
]
] |
quant-ph/0603145
|
Chil-Min Kim
|
Yun Jin Choi, Young-Jai Park, Chil-Min Kim, and Jaewan Kim
|
Multipartite Quantum Secret Sharing using Not-So-Weak Qubits
|
4 pages, 3 figures, an author is added
| null |
10.3938/jkps.51.4
| null |
quant-ph
| null |
We propose a new quantum secret sharing scheme using a single non-entangled
qubit. In the scheme, by transmitting a qubit to the next party sequentially, a
sender can securely transmit a secret message to $N$ receivers who could only
decode the message cooperatively after randomly shuffling the polarization of
the qubit. We explain this quantum secret sharing scheme into the one between a
sender and two receivers, and generalize the scheme between a sender and $N$
receivers. Since our scheme is capable of using a faint coherent pulse as a
qubit, it is experimentally feasible within current technology.
|
[
{
"version": "v1",
"created": "Thu, 16 Mar 2006 09:30:04 GMT"
},
{
"version": "v2",
"created": "Wed, 7 Feb 2007 08:36:34 GMT"
},
{
"version": "v3",
"created": "Sat, 10 Feb 2007 07:40:22 GMT"
}
] | 2015-06-26T00:00:00 |
[
[
"Choi",
"Yun Jin",
""
],
[
"Park",
"Young-Jai",
""
],
[
"Kim",
"Chil-Min",
""
],
[
"Kim",
"Jaewan",
""
]
] |
quant-ph/0603146
|
Ian Durham
|
I. T. Durham
|
Sir Arthur Eddington and the Foundations of Modern Physics
|
Doctoral dissertation, School of Mathematics, University of St.
Andrews, April 2005 (external examiner: S.R.D. French, University of Leeds);
289 pages; includes photographs; **12.5 MB file**
| null | null | null |
quant-ph gr-qc physics.hist-ph
| null |
This doctoral dissertation presents an in-depth analysis of the first six
chapters of Eddington's Fundamental Theory, sometimes referred to as his
'statistical' theory, in the context of discoveries and advancements made since
its original publication in 1946. In particular, the analysis is focused on
being in the context of the foundations of quantum mechanics and quantum field
theory. The results of the analysis illuminate a number of novel methods and
techniques that, though not always correct, may prove to be enlightening and
even useful for future research in quantum foundations.
|
[
{
"version": "v1",
"created": "Thu, 16 Mar 2006 15:06:07 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Durham",
"I. T.",
""
]
] |
quant-ph/0603147
|
S. Wallentowitz
|
D. Ivanov and S. Wallentowitz
|
Test of the quantumness of atom-atom correlations in a bosonic gas
| null |
Europhys. Lett. 73, 499 (2006)
|
10.1209/epl/i2005-10435-1
| null |
quant-ph
| null |
It is shown how the quantumness of atom-atom correlations in a trapped
bosonic gas can be made observable. Application of continuous feedback control
of the center of mass of the atomic cloud is shown to generate oscillations of
the spatial extension of the cloud, whose amplitude can be directly used as a
characterization of atom-atom correlations. Feedback parameters can be chosen
such that the violation of a Schwarz inequality for atom-atom correlations can
be tested at noise levels much higher than the standard quantum limit.
|
[
{
"version": "v1",
"created": "Thu, 16 Mar 2006 16:10:22 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Ivanov",
"D.",
""
],
[
"Wallentowitz",
"S.",
""
]
] |
quant-ph/0603148
|
Martina Avellino
|
M. Avellino, A.J. Fisher, S. Bose
|
Quantum Communication in Spin Systems With Long-Range Interactions
|
15 pages, 8 eps figures, updated references, corrected text and
corrected figs. 1, 4 and 5
|
PHYSICAL REVIEW A 74, 012321 (2006)
|
10.1103/PhysRevA.74.012321
| null |
quant-ph
| null |
We calculate the fidelity of transmission of a single qubit between distant
sites on semi-infinite and finite chains of spins coupled via the magnetic
dipole interaction. We show that such systems often perform better than their
Heisenberg nearest-neighbour coupled counterparts, and that fidelities closely
approaching unity can be attained between the ends of finite chains without any
special engineering of the system, although state transfer becomes slow in long
chains. We discuss possible optimization methods, and find that, for any
length, the best compromise between the quality and the speed of the
communication is obtained in a nearly uniform chain of 4 spins.
|
[
{
"version": "v1",
"created": "Thu, 16 Mar 2006 16:14:12 GMT"
},
{
"version": "v2",
"created": "Wed, 21 Jun 2006 10:35:28 GMT"
},
{
"version": "v3",
"created": "Thu, 29 Jun 2006 16:38:57 GMT"
},
{
"version": "v4",
"created": "Tue, 11 Jul 2006 14:23:51 GMT"
},
{
"version": "v5",
"created": "Wed, 2 Aug 2006 16:24:56 GMT"
},
{
"version": "v6",
"created": "Thu, 29 Nov 2007 13:47:39 GMT"
}
] | 2007-11-29T00:00:00 |
[
[
"Avellino",
"M.",
""
],
[
"Fisher",
"A. J.",
""
],
[
"Bose",
"S.",
""
]
] |
quant-ph/0603149
|
Adam Miranowicz
|
Adam Miranowicz and Wieslaw Leonski
|
Two-mode optical state truncation and generation of maximally entangled
states in pumped nonlinear couplers
|
11 pages, 12 figures, to appear in J. Phys. B
|
J. Phys. B 39, 1683-1700 (2006)
|
10.1088/0953-4075/39/7/011
| null |
quant-ph
| null |
Schemes for optical-state truncation of two cavity modes are analysed. The
systems, referred to as the nonlinear quantum scissors devices, comprise two
coupled nonlinear oscillators (Kerr nonlinear coupler) with one or two of them
pumped by external classical fields. It is shown that the quantum evolution of
the pumped couplers can be closed in a two-qubit Hilbert space spanned by
vacuum and single-photon states only. Thus, the pumped couplers can behave as a
two-qubit system. Analysis of time evolution of the quantum entanglement shows
that Bell states can be generated. A possible implementation of the couplers is
suggested in a pumped double-ring cavity with resonantly enhanced Kerr
nonlinearities in an electromagnetically-induced transparency scheme. The
fragility of the generated states and their entanglement due to the standard
dissipation and phase damping are discussed by numerically solving two types of
master equations.
|
[
{
"version": "v1",
"created": "Thu, 16 Mar 2006 18:39:20 GMT"
}
] | 2009-08-03T00:00:00 |
[
[
"Miranowicz",
"Adam",
""
],
[
"Leonski",
"Wieslaw",
""
]
] |
quant-ph/0603150
|
Ilya Fushman
|
Ilya Fushman and Jelena Vuckovic
|
Analysis of a Quantum Nondemolition Measurement Scheme Based on Kerr
Nonlinearity in Photonic Crystal Waveguides
| null | null |
10.1364/OE.15.005559
| null |
quant-ph physics.optics
| null |
We discuss the feasibility of a quantum nondemolition measurement (QND) of
photon number based on cross phase modulation due to the Kerr effect in
Photonic Crystal Waveguides (PCWs). In particular, we derive the equations for
two modes propagating in PCWs and their coupling by a third order nonlinearity.
The reduced group velocity and small cross-sectional area of the PCW lead to an
enhancement of the interaction relative to bulk materials. We show that in
principle, such experiments may be feasible with current photonic technologies,
although they are limited by material properties. Our analysis of the
propagation equations is sufficiently general to be applicable to the study of
soliton formation, all-optical switching and can be extended to processes
involving other orders of the nonlinearity.
|
[
{
"version": "v1",
"created": "Thu, 16 Mar 2006 22:30:38 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Fushman",
"Ilya",
""
],
[
"Vuckovic",
"Jelena",
""
]
] |
quant-ph/0603151
|
Mario Ziman
|
Mario Ziman
|
Notes on optimality of direct characterisation of quantum dynamics
|
3 pages
| null | null | null |
quant-ph
| null |
We argue that the claimed optimality of a new process tomography method
suggested in [quant-ph/0601033] and [quant-ph/0601034] is based on not
completely fair comparison that does not take into account the available
information in an equal way. We also argue that the method is not a new process
tomography scheme, but rather represents an interesting modification of ancilla
assisted process tomography method. In our opinion these modifications require
deeper understanding and further investigation.
|
[
{
"version": "v1",
"created": "Fri, 17 Mar 2006 01:14:28 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Ziman",
"Mario",
""
]
] |
quant-ph/0603152
|
Lan Zhou
|
Lan Zhou, F. M. Hu, Jing Lu, C. P. Sun
|
Electromagnetic manipulation for anti-Zeno effect in an engineered
quantum tunneling process
|
6 pages, 5 figures
| null |
10.1103/PhysRevA.74.032102
| null |
quant-ph
| null |
We investigate the quantum Zeno and anti-Zeno effects for the irreversible
quantum tunneling from a quantum dot to a ring array of quantum dots. By
modeling the total system with the Anderson-Fano-Lee model, it is found that
the transition from the quantum Zeno effect to quantum anti-Zeno effect can
happen as the magnetic flux and the gate voltage were adjusted.
|
[
{
"version": "v1",
"created": "Fri, 17 Mar 2006 07:36:44 GMT"
},
{
"version": "v2",
"created": "Fri, 1 Sep 2006 10:51:16 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Zhou",
"Lan",
""
],
[
"Hu",
"F. M.",
""
],
[
"Lu",
"Jing",
""
],
[
"Sun",
"C. P.",
""
]
] |
quant-ph/0603153
|
Dominique Delande
|
Guillaume Labeyrie (INLN), Dominique Delande (LKB - Jussieu), Robin
Kaiser (INLN), Christian Miniatura (INLN)
|
Light transport in cold atoms and thermal decoherence
|
4 pages - submitted to Physical Review Letters
|
Physical Review Letters 97 (07/07/2006) 013004
|
10.1103/PhysRevLett.97.013004
| null |
quant-ph cond-mat.other
| null |
By using the coherent backscattering interference effect, we investigate
experimentally and theoretically how coherent transport of light inside a cold
atomic vapour is affected by the residual motion of atomic scatterers. As the
temperature of the atomic cloud increases, the interference contrast
dramatically decreases emphazising the role of motion-induced decoherence for
resonant scatterers even in the sub-Doppler regime of temperature. We derive
analytical expressions for the corresponding coherence time.
|
[
{
"version": "v1",
"created": "Fri, 17 Mar 2006 12:32:31 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Labeyrie",
"Guillaume",
"",
"INLN"
],
[
"Delande",
"Dominique",
"",
"LKB - Jussieu"
],
[
"Kaiser",
"Robin",
"",
"INLN"
],
[
"Miniatura",
"Christian",
"",
"INLN"
]
] |
quant-ph/0603154
|
Chi-Yee Cheung
|
Chi-Yee Cheung
|
Secure Quantum Bit Commitment Using Unstable Particles
|
4 pages, 0 figure, REVTEX 4; protocol modified
| null | null | null |
quant-ph
| null |
Using unstable particles which decay by emitting neutrinos, we propose a
quantum bit commitment protocol that is humanly impossible to break. Neutrinos
carry away quantum information, but their interaction with matter is so weak
that it would take an astronomically-sized machine just to catch them, not to
mention performing controlled unitary operations on them. As a result quantum
information is lost, and cheating is not possible even if the participants had
access to the most powerful quantum computers that could ever be built.
Therefore, for all practical purposes, our new protocol is as good as
unconditionally secure.
|
[
{
"version": "v1",
"created": "Fri, 17 Mar 2006 16:12:32 GMT"
},
{
"version": "v2",
"created": "Wed, 22 Mar 2006 10:23:41 GMT"
},
{
"version": "v3",
"created": "Tue, 28 Mar 2006 12:03:31 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Cheung",
"Chi-Yee",
""
]
] |
quant-ph/0603155
|
Dmitry Arbatsky
|
D. A. Arbatsky
|
The certainty principle II: Proof of the uncertainty principle
|
One paper, in Russian and in English, no figures
| null | null | null |
quant-ph
| null |
A more detailed derivation of the Heisenberg uncertainty principle from the
certainty principle is given.
|
[
{
"version": "v1",
"created": "Fri, 17 Mar 2006 16:03:41 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Arbatsky",
"D. A.",
""
]
] |
quant-ph/0603156
|
C.M. Chandrashekar
|
C.M. Chandrashekar
|
Implementing the one-dimensional quantum (Hadamard) walk using a
Bose-Einstein Condensate
|
7 pages, 3 figures
|
Phys. Rev. A . 74, 032307 (2006)
|
10.1103/PhysRevA.74.032307
| null |
quant-ph
| null |
We propose a scheme to implement the simplest and best-studied version of
quantum random walk, the discrete Hadamard walk, in one dimension using
coherent macroscopic sample of ultracold atoms, Bose-Einstein condensate (BEC).
Implementation of quantum walk using BEC gives access to the familiar quantum
phenomena on a macroscopic scale. This paper uses rf pulse to implement
Hadamard operation (rotation) and stimulated Raman transition technique as
unitary shift operator. The scheme suggests implementation of Hadamard
operation and unitary shift operator while the BEC is trapped in long Rayleigh
range optical dipole trap. The Hadamard rotation and a unitary shift operator
on BEC prepared in one of the internal state followed by a bit flip operation,
implements one step of the Hadamard walk. To realize a sizable number of steps,
the process is iterated without resorting to intermediate measurement. With
current dipole trap technology it should be possible to implement enough steps
to experimentally highlight the discrete quantum random walk using a BEC
leading to further exploration of quantum random walks and its applications.
|
[
{
"version": "v1",
"created": "Fri, 17 Mar 2006 17:10:59 GMT"
},
{
"version": "v2",
"created": "Fri, 30 Jun 2006 12:04:40 GMT"
},
{
"version": "v3",
"created": "Mon, 24 Jul 2006 05:43:46 GMT"
},
{
"version": "v4",
"created": "Tue, 12 Sep 2006 04:24:25 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Chandrashekar",
"C. M.",
""
]
] |
quant-ph/0603157
|
Daniel Kuan Li Oi
|
Daniel K. L. Oi and Johan Aberg
|
Fidelity and Coherence Measures from Interference
|
4 pages, 4 Figures
| null |
10.1103/PhysRevLett.97.220404
| null |
quant-ph
| null |
By utilizing single particle interferometry, the fidelity or coherence of a
pair of quantum states is identified with their capacity for interference. We
consider processes acting on the internal degree of freedom (e.g., spin or
polarization) of the interfering particle, preparing it in states \rho_{A} or
\rho_{B} in the respective path of the interferometer. The maximal visibility
depends on the choice of interferometer, as well as the locality or
non-locality of the preparations, but otherwise depends only on the states
\rho_{A} and \rho_{B} and not the individual preparation processes themselves.
This allows us to define interferometric measures which probe locality and
correlation properties of spatially or temporally separated processes, and can
be used to differentiate between processes that cannot be distinguished by
direct process tomography using only the internal state of the particle.
|
[
{
"version": "v1",
"created": "Fri, 17 Mar 2006 17:46:49 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Oi",
"Daniel K. L.",
""
],
[
"Aberg",
"Johan",
""
]
] |
quant-ph/0603158
|
Deborah Watson
|
M. Dunn, D.K. Watson and J.G. Loeser
|
N Identical Particles Under Quantum Confinement: A Many-Body Dimensional
Perturbation Theory Approach II, The Lowest-Order Wave Function I
|
52 pages
| null | null | null |
quant-ph
| null |
In this paper we continue our development of a dimensional perturbation
theory (DPT) treatment of N identical particles under quantum confinement. DPT
is a beyond-mean-field method which is applicable to both weakly and
strongly-interacting systems and can be used to connect both limits. In a
previous paper we developed the formalism for low-order energies and excitation
frequencies. This formalism has been applied to atoms, Bose-Einstein
condensates and quantum dots. One major advantage of the method is that N
appears as a parameter in the analytical expressions for the energy and so
results for N up to a few thousand are easy to obtain. Other properties
however, are also of interest, for example the density profile in the case of a
BEC,and larger N results are desirable as well. The latter case requires us to
go to higher orders in DPT. These calculations require as input zeroth-order
wave functions and this paper, along with a subsequent paper, addresses this
issue.
|
[
{
"version": "v1",
"created": "Fri, 17 Mar 2006 20:32:34 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Dunn",
"M.",
""
],
[
"Watson",
"D. K.",
""
],
[
"Loeser",
"J. G.",
""
]
] |
quant-ph/0603159
|
Fumiko Yamaguchi
|
Fumiko Yamaguchi and Yoshihisa Yamamoto
|
A naturally error suppressing quantum memory
| null | null | null | null |
quant-ph
| null |
We propose a method to construct quantum storage wherein the phase error due
to decoherence is naturally suppressed without constant error detection and
correction. As an example, we describe a quantum memory made of two physical
qubits encoded in the ground state of a two-qubit phase-error detecting code.
Such a system can be simulated by introducing a coupling between the two
physical qubits. This method is effective for physical systems in which the
$T_1$ decay process is negligible but coherence is limited by the $T_2$ decay
process. We take trapped ions as a possible example to apply the natural
suppression method and show that the $T_2$ decay time due to slow ambient
fluctuating fields at the physical qubits can be lengthened as much as $10^4$.
|
[
{
"version": "v1",
"created": "Sat, 18 Mar 2006 00:19:27 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Yamaguchi",
"Fumiko",
""
],
[
"Yamamoto",
"Yoshihisa",
""
]
] |
quant-ph/0603160
|
Mile Gu
|
Michael A. Nielsen, Mark R. Dowling, Mile Gu and Andrew C. Doherty
|
Optimal control, geometry, and quantum computing
|
7 Pages Added Full Names to Authors
| null |
10.1103/PhysRevA.73.062323
| null |
quant-ph
| null |
We prove upper and lower bounds relating the quantum gate complexity of a
unitary operation, U, to the optimal control cost associated to the synthesis
of U. These bounds apply for any optimal control problem, and can be used to
show that the quantum gate complexity is essentially equivalent to the optimal
control cost for a wide range of problems, including time-optimal control and
finding minimal distances on certain Riemannian, subriemannian, and Finslerian
manifolds. These results generalize the results of Nielsen, Dowling, Gu, and
Doherty, Science 311, 1133-1135 (2006), which showed that the gate complexity
can be related to distances on a Riemannian manifold
|
[
{
"version": "v1",
"created": "Sun, 19 Mar 2006 02:13:05 GMT"
},
{
"version": "v2",
"created": "Tue, 21 Mar 2006 16:34:26 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Nielsen",
"Michael A.",
""
],
[
"Dowling",
"Mark R.",
""
],
[
"Gu",
"Mile",
""
],
[
"Doherty",
"Andrew C.",
""
]
] |
quant-ph/0603161
|
Mile Gu
|
Michael A. Nielsen, Mark R. Dowling, Mile Gu and Andrew C. Doherty
|
Quantum Computation as Geometry
|
13 Pages, 1 Figure
|
M. A. Nielsen, M. Dowling, M. Gu, A. Doherty, Science 311, 1133
(2006)
|
10.1126/science.1121541
| null |
quant-ph
| null |
Quantum computers hold great promise, but it remains a challenge to find
efficient quantum circuits that solve interesting computational problems. We
show that finding optimal quantum circuits is essentially equivalent to finding
the shortest path between two points in a certain curved geometry. By recasting
the problem of finding quantum circuits as a geometric problem, we open up the
possibility of using the mathematical techniques of Riemannian geometry to
suggest new quantum algorithms, or to prove limitations on the power of quantum
computers.
|
[
{
"version": "v1",
"created": "Sun, 19 Mar 2006 02:36:28 GMT"
},
{
"version": "v2",
"created": "Tue, 21 Mar 2006 16:50:14 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Nielsen",
"Michael A.",
""
],
[
"Dowling",
"Mark R.",
""
],
[
"Gu",
"Mile",
""
],
[
"Doherty",
"Andrew C.",
""
]
] |
quant-ph/0603162
|
Satoshi Ishizaka
|
Satoshi Ishizaka
|
Strong monotonicity in mixed-state entanglement manipulation
|
6 pages and 1 figure. A brief discussion about the connection to
asymptotic distillability was added
|
Phys. Rev. A 73, 062308 (2006)
|
10.1103/PhysRevA.73.062308
| null |
quant-ph
| null |
A strong entanglement monotone, which never increases under local operations
and classical communications (LOCC), restricts quantum entanglement
manipulation more strongly than the usual monotone since the usual one does not
increase on average under LOCC. We propose new strong monotones in mixed-state
entanglement manipulation under LOCC. These are related to the decomposability
and 1-positivity of an operator constructed from a quantum state, and reveal
geometrical characteristics of entangled states. These are lower bounded by the
negativity or generalized robustness of entanglement.
|
[
{
"version": "v1",
"created": "Mon, 20 Mar 2006 07:04:14 GMT"
},
{
"version": "v2",
"created": "Tue, 9 May 2006 04:38:27 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Ishizaka",
"Satoshi",
""
]
] |
quant-ph/0603163
|
Richard Jozsa
|
Richard Jozsa
|
On the simulation of quantum circuits
|
12 pages, latex
| null | null | null |
quant-ph
| null |
We consider recent works on the simulation of quantum circuits using the
formalism of matrix product states and the formalism of contracting tensor
networks. We provide simplified direct proofs of many of these results,
extending an explicit class of efficiently simulable circuits (log depth
circuits with 2-qubit gates of limited range) to the following: let C be any
poly sized quantum circuit (generally of poly depth too) on n qubits comprising
1- and 2- qubit gates and 1-qubit measurements (with 2-qubit gates acting on
arbitrary pairs of qubit lines). For each qubit line j let D_j be the number of
2-qubit gates that touch or cross the line j i.e. the number of 2-qubit gates
that are applied to qubits i,k with i \leq j \leq k. Let D=max_j D_j. Then the
quantum process can be classically simulated in time n poly(2^D). Thus if
D=O(log n) then C may be efficiently classically simulated.
|
[
{
"version": "v1",
"created": "Sun, 19 Mar 2006 12:18:14 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Jozsa",
"Richard",
""
]
] |
quant-ph/0603164
|
Lajos Di\'osi
|
Lajos Diosi
|
Continuous Wave Function Collapse in Quantum-Electrodynamics?
|
Invited talk at Conf. "On the present status of quantum mechanics",
7-9 September, 2005, Mali Losinj, Croatia
| null |
10.1063/1.2219358
| null |
quant-ph
| null |
Time-continuous wavefunction collapse mechanisms n o t restricted to
markovian approximation have been found only a few years ago, and have left
many issues open. The results apply formally to the standard relativistic
quantum-electrodynamics. I present a generalized Schrodinger equation driven by
a certain complex stochastic field. The equation reproduces the e x a c t
dynamics of the interacting fermions in QED. The state of the fermions appears
to collapse continuously, due to their interaction with the photonic degrees of
freedom. Even the formal study is instructive for the foundations of quantum
mechanics and of field theory as well.
|
[
{
"version": "v1",
"created": "Sun, 19 Mar 2006 14:29:15 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Diosi",
"Lajos",
""
]
] |
quant-ph/0603165
|
Olimpia Lombardi
|
Mario Castagnino
|
The equilibrium limit of the Casati-Prosen model
|
6 pages, no figures
| null |
10.1016/j.physleta.2006.04.024
| null |
quant-ph
| null |
An alternative explanation of the decoherence in the Casati-Prosen model is
presented. It is based on the Self Induced Decoherence formalism extended to
non-integrable systems.
|
[
{
"version": "v1",
"created": "Sun, 19 Mar 2006 20:28:18 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Castagnino",
"Mario",
""
]
] |
quant-ph/0603166
|
Mario Ziman
|
Mario Ziman
|
Quantum process tomography: the role of initial correlations
|
7 pages, comments welcome, references added
| null | null | null |
quant-ph
| null |
We address the problem of quantum process tomography with the preparators
producing states correlated with the environmental degrees of freedom that play
role in the system-environment interactions. We discuss the physical
situations, in which the dynamics is described by nonlinear, or noncompletely
positive transformations. In particular, we show that arbitrary mapping
$\varrho_{\rm in}\to\varrho_{\rm out}$ can be realized by using appropriate set
of preparators and applying the unitary operation SWAP. The experimental
``realization'' of perfect NOT operation is presented. We address the problem
of the verification of the compatibility of the preparator devices with the
estimating process. The evolution map describing the dynamics in arbitrary time
interval is known not to be completely positive, but still linear. The
tomography and general properties of these maps are discussed.
|
[
{
"version": "v1",
"created": "Sun, 19 Mar 2006 23:56:53 GMT"
},
{
"version": "v2",
"created": "Fri, 24 Mar 2006 00:12:34 GMT"
},
{
"version": "v3",
"created": "Fri, 1 Sep 2006 15:32:09 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Ziman",
"Mario",
""
]
] |
quant-ph/0603167
|
Fabio Antonio Bovino
|
F.A. Bovino, M. Giardina, K. Svozil and V. Vedral
|
Spatial Orientation using Quantum Telepathy
| null | null | null | null |
quant-ph
| null |
We implemented the protocol of entanglement assisted orientation in the space
proposed by Brukner et al (quant-ph/0603167). We used min-max principle to
evaluate the optimal entangled state and the optimal direction of polarization
measurements which violate the classical bound.
|
[
{
"version": "v1",
"created": "Mon, 20 Mar 2006 19:39:58 GMT"
},
{
"version": "v2",
"created": "Wed, 29 Mar 2006 11:08:32 GMT"
},
{
"version": "v3",
"created": "Mon, 10 Apr 2006 23:48:57 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Bovino",
"F. A.",
""
],
[
"Giardina",
"M.",
""
],
[
"Svozil",
"K.",
""
],
[
"Vedral",
"V.",
""
]
] |
quant-ph/0603168
|
Giulio Chiribella
|
G. Chiribella and G. M. D'Ariano
|
Extremal covariant measurements
|
11 pages, no figures
|
J. Math. Phys. 47, 092107 (2006)
|
10.1063/1.2349481
| null |
quant-ph
| null |
We characterize the extremal points of the convex set of quantum measurements
that are covariant under a finite-dimensional projective representation of a
compact group, with action of the group on the measurement probability space
which is generally non-transitive. In this case the POVM density is made of
multiple orbits of positive operators, and, in the case of extremal
measurements, we provide a bound for the number of orbits and for the rank of
POVM elements. Two relevant applications are considered, concerning state
discrimination with mutually unbiased bases and the maximization of the mutual
information.
|
[
{
"version": "v1",
"created": "Mon, 20 Mar 2006 11:02:35 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Chiribella",
"G.",
""
],
[
"D'Ariano",
"G. M.",
""
]
] |
quant-ph/0603169
|
Kordian A. Smolinski
|
P. Caban, J. Rembielinski, K. A. Smolinski, Z. Walczak, M. Wlodarczyk
|
An open quantum system approach to EPR correlations in K0-K0 system
|
14 pp. no figs
|
Phys.Lett. A357 (2006) 6-11
|
10.1016/j.physleta.2006.04.102
| null |
quant-ph
| null |
We find the time evolution of the system of two non-interacting unstable
particles, distinguishable as well as identical ones, in arbitrary reference
frame having only the Kraus operators governing the evolution of its components
in the rest frame. We than calculate in the rigorous way
Einstein-Podolsky-Rosen quantum correlation functions for K0-K0 system in the
singlet state taking into account CP-violation and decoherence and show that
the results are exactly the same despite the fact we treat kaons as
distinguishable or identical particles which means that the statistics of the
particles plays no role, at least in considered cases.
|
[
{
"version": "v1",
"created": "Mon, 20 Mar 2006 12:59:57 GMT"
}
] | 2010-04-05T00:00:00 |
[
[
"Caban",
"P.",
""
],
[
"Rembielinski",
"J.",
""
],
[
"Smolinski",
"K. A.",
""
],
[
"Walczak",
"Z.",
""
],
[
"Wlodarczyk",
"M.",
""
]
] |
quant-ph/0603170
|
Thomas Curtright
|
Thomas Curtright, Luca Mezincescu, and David Schuster
|
Supersymmetric Biorthogonal Quantum Systems
|
Changes are made to conform to the published version. In particular,
some errors are corrected on pp 12-13
|
J.Math.Phys.48:092108,2007
|
10.1063/1.2191367
| null |
quant-ph hep-th math-ph math.MP
| null |
We discuss supersymmetric biorthogonal systems, with emphasis given to the
periodic solutions that occur at spectral singularities of PT symmetric models.
For these periodic solutions, the dual functions are associated polynomials
that obey inhomogeneous equations. We construct in detail some explicit
examples for the supersymmetric pairs of potentials V_{+/-}(z) = -U(z)^2 +/-
z(d/(dz))U(z) where U(z) = \sum_{k>0}u_{k}z^{k}. In particular, we consider the
cases generated by U(z) = z and z/(1-z). We also briefly consider the effects
of magnetic vector potentials on the partition functions of these systems.
|
[
{
"version": "v1",
"created": "Mon, 20 Mar 2006 14:25:10 GMT"
},
{
"version": "v2",
"created": "Sun, 26 Aug 2007 22:18:33 GMT"
}
] | 2008-11-26T00:00:00 |
[
[
"Curtright",
"Thomas",
""
],
[
"Mezincescu",
"Luca",
""
],
[
"Schuster",
"David",
""
]
] |
quant-ph/0603171
|
Luca Marinatto
|
GianCarlo Ghirardi and Luca Marinatto
|
Hardy's criterion of nonlocality for mixed states
|
7 pages, RevTex
|
Phys. Rev. A 73, 032102 (2006)
|
10.1103/PhysRevA.73.032102
| null |
quant-ph
| null |
We generalize Hardy's proof of nonlocality to the case of bipartite mixed
statistical operators, and we exhibit a necessary condition which has to be
satisfied by any given mixed state $\sigma$ in order that a local and realistic
hidden variable model exists which accounts for the quantum mechanical
predictions implied by $\sigma$. Failure of this condition will imply both the
impossibility of any local explanation of certain joint probability
distributions in terms of hidden variables and the nonseparability of the
considered mixed statistical operator. Our result can be also used to determine
the maximum amount of noise, arising from imperfect experimental
implementations of the original Hardy's proof of nonlocality, in presence of
which it is still possible to put into evidence the nonlocal features of
certain mixed states.
|
[
{
"version": "v1",
"created": "Mon, 20 Mar 2006 15:56:30 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Ghirardi",
"GianCarlo",
""
],
[
"Marinatto",
"Luca",
""
]
] |
quant-ph/0603172
|
Sandro Sozzo
|
Claudio Garola and Sandro Sozzo
|
On the Notion of Proposition in Classical and Quantum Mechanics
|
22 pages. To appear in "The Foundations of Quantum Mechanics:
Historical Analysis and Open Questions-Cesena 2004", C. Garola, A. Rossi and
S. Sozzo Eds., World Scientific, Singapore, 2006
| null | null | null |
quant-ph
| null |
The term proposition usually denotes in quantum mechanics (QM) an element of
(standard) quantum logic (QL). Within the orthodox interpretation of QM the
propositions of QL cannot be associated with sentences of a language stating
properties of individual samples of a physical system, since properties are
nonobjective in QM. This makes the interpretation of propositions
problematical. The difficulty can be removed by adopting the objective
interpretation of QM proposed by one of the authors (semantic realism, or SR,
interpretation). In this case, a unified perspective can be adopted for QM and
classical mechanics (CM), and a simple first order predicate calculus L(x) with
Tarskian semantics can be constructed such that one can associate a physical
proposition (i.e., a set of physical states) with every sentence of L(x). The
set $P^{f}$ of all physical propositions is partially ordered and contains a
subset $P^{f}_{T}$ of testable physical propositions whose order structure
depends on the criteria of testability established by the physical theory. In
particular, $P^{f}_{T}$ turns out to be a Boolean lattice in CM, while it can
be identified with QL in QM. Hence the propositions of QL can be associated
with sentences of L(x), or also with the sentences of a suitable quantum
language $L_{TQ}(x)$, and the structure of QL characterizes the notion of
testability in QM. One can then show that the notion of quantum truth does not
conflict with the classical notion of truth within this perspective.
Furthermore, the interpretation of QL propounded here proves to be equivalent
to a previous pragmatic interpretation worked out by one of the authors, and
can be embodied within a more general perspective which considers states as
first order predicates of a broader language with a Kripkean semantics.
|
[
{
"version": "v1",
"created": "Mon, 20 Mar 2006 16:09:21 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Garola",
"Claudio",
""
],
[
"Sozzo",
"Sandro",
""
]
] |
quant-ph/0603173
|
Julia Kempe
|
Dmytro Gavinsky, Julia Kempe, Ronald de Wolf
|
Strengths and Weaknesses of Quantum Fingerprinting
|
13 pages, no figures, to appear in CCC'06
|
Proc. 21st CCC (Complexity), p. 288-295 (2006)
| null | null |
quant-ph cs.CC
| null |
We study the power of quantum fingerprints in the simultaneous message
passing (SMP) setting of communication complexity. Yao recently showed how to
simulate, with exponential overhead, classical shared-randomness SMP protocols
by means of quantum SMP protocols without shared randomness
($Q^\parallel$-protocols). Our first result is to extend Yao's simulation to
the strongest possible model: every many-round quantum protocol with unlimited
shared entanglement can be simulated, with exponential overhead, by
$Q^\parallel$-protocols. We apply our technique to obtain an efficient
$Q^\parallel$-protocol for a function which cannot be efficiently solved
through more restricted simulations. Second, we tightly characterize the power
of the quantum fingerprinting technique by making a connection to arrangements
of homogeneous halfspaces with maximal margin. These arrangements have been
well studied in computational learning theory, and we use some strong results
obtained in this area to exhibit weaknesses of quantum fingerprinting. In
particular, this implies that for almost all functions, quantum fingerprinting
protocols are exponentially worse than classical deterministic SMP protocols.
|
[
{
"version": "v1",
"created": "Mon, 20 Mar 2006 16:13:53 GMT"
}
] | 2022-03-29T00:00:00 |
[
[
"Gavinsky",
"Dmytro",
""
],
[
"Kempe",
"Julia",
""
],
[
"de Wolf",
"Ronald",
""
]
] |
quant-ph/0603174
|
Jaromir Fiurasek
|
Lucie Bartuskova, Antonin Cernoch, Radim Filip, Jaromir Fiurasek, Jan
Soubusta, Miloslav Dusek
|
Optical implementation of the encoding of two qubits to a single qutrit
|
6 pages, 3 figures, RevTeX 4
|
Phys. Rev. A 74, 022325 (2006).
|
10.1103/PhysRevA.74.022325
| null |
quant-ph
| null |
We have devised an optical scheme for the recently proposed protocol for
encoding two qubits into one qutrit. In this protocol, Alice encodes an
arbitrary pure product state of two qubits into a state of one qutrit. Bob can
then restore error-free any of the two encoded qubit states but not both of
them simultaneously. We have successfully realized this scheme experimentally
using spatial-mode encoding. Each qubit (qutrit) was represented by a single
photon that could propagate through two (three) separate fibers. We
theoretically propose two generalizations of the original protocol. We have
found a probabilistic operation that enables to retrieve both qubits
simultaneously with the average fidelity above 90% and we have proposed
extension of the original encoding transformation to encode N qubits into one
(N+1)-dimensional system.
|
[
{
"version": "v1",
"created": "Mon, 20 Mar 2006 16:49:46 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Bartuskova",
"Lucie",
""
],
[
"Cernoch",
"Antonin",
""
],
[
"Filip",
"Radim",
""
],
[
"Fiurasek",
"Jaromir",
""
],
[
"Soubusta",
"Jan",
""
],
[
"Dusek",
"Miloslav",
""
]
] |
quant-ph/0603175
|
Sabine Jansen
|
Sabine Jansen, Mary-Beth Ruskai, Ruedi Seiler
|
Bounds for the adiabatic approximation with applications to quantum
computation
|
15 pages, one figure. Two comments added in Secs. 2 and 5
|
J. Math. Phys. 48, 102111 (2007)
|
10.1063/1.2798382
| null |
quant-ph
| null |
We present straightforward proofs of estimates used in the adiabatic
approximation. The gap dependence is analyzed explicitly. We apply the result
to interpolating Hamiltonians of interest in quantum computing.
|
[
{
"version": "v1",
"created": "Mon, 20 Mar 2006 17:07:32 GMT"
},
{
"version": "v2",
"created": "Fri, 31 Mar 2006 17:07:41 GMT"
},
{
"version": "v3",
"created": "Thu, 8 Nov 2007 18:46:44 GMT"
}
] | 2007-11-08T00:00:00 |
[
[
"Jansen",
"Sabine",
""
],
[
"Ruskai",
"Mary-Beth",
""
],
[
"Seiler",
"Ruedi",
""
]
] |
quant-ph/0603176
|
R. de la Madrid
|
R. de la Madrid
|
The rigged Hilbert space approach to the Lippmann-Schwinger equation.
Part I
|
34 pages, 1 figure
|
J. Phys. A: Math. Gen. 39 (2006) 3949-3979
|
10.1088/0305-4470/39/15/008
| null |
quant-ph hep-th math-ph math.MP
| null |
We exemplify the way the rigged Hilbert space deals with the
Lippmann-Schwinger equation by way of the spherical shell potential. We
explicitly construct the Lippmann-Schwinger bras and kets along with their
energy representation, their time evolution and the rigged Hilbert spaces to
which they belong. It will be concluded that the natural setting for the
solutions of the Lippmann-Schwinger equation--and therefore for scattering
theory--is the rigged Hilbert space rather than just the Hilbert space.
|
[
{
"version": "v1",
"created": "Mon, 20 Mar 2006 20:12:45 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"de la Madrid",
"R.",
""
]
] |
quant-ph/0603177
|
R. de la Madrid
|
R. de la Madrid
|
The rigged Hilbert space approach to the Lippmann-Schwinger equation.
Part II: The analytic continuation of the Lippmann-Schwinger bras and kets
|
32 pages, 3 figures
|
J. Phys. A: Math. Gen. 39 (2006) 3981-4009
|
10.1088/0305-4470/39/15/009
| null |
quant-ph hep-th math-ph math.MP
| null |
The analytic continuation of the Lippmann-Schwinger bras and kets is obtained
and characterized. It is shown that the natural mathematical setting for the
analytic continuation of the solutions of the Lippmann-Schwinger equation is
the rigged Hilbert space rather than just the Hilbert space. It is also argued
that this analytic continuation entails the imposition of a time asymmetric
boundary condition upon the group time evolution, resulting into a semigroup
time evolution. Physically, the semigroup time evolution is simply a (retarded
or advanced) propagator.
|
[
{
"version": "v1",
"created": "Mon, 20 Mar 2006 20:13:26 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"de la Madrid",
"R.",
""
]
] |
quant-ph/0603178
|
Chengming Bai
|
Cheng-Ming Bai, Mo-Lin Ge, Kang Xue, Hong-Biao Zhang
|
Yangian and Applications
|
33pages, 1 figure
| null | null | null |
quant-ph
| null |
In this paper, the Yangian relations are tremendously simplified for Yangians
associated to SU(2), SU(3), SO(5) and SO(6) based on RTT relations that much
benefit the realization of Yangian in physics. The physical meaning and some
applications of Yangian have been shown.
|
[
{
"version": "v1",
"created": "Tue, 21 Mar 2006 01:45:11 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Bai",
"Cheng-Ming",
""
],
[
"Ge",
"Mo-Lin",
""
],
[
"Xue",
"Kang",
""
],
[
"Zhang",
"Hong-Biao",
""
]
] |
quant-ph/0603179
|
Man-Hong Yung
|
Man-Hong Yung
|
Quantum Speed Limit for Perfect State Transfer in One Dimension
|
5 pages, no figure; improved version
|
Phys. Rev. A 74, 030303(R) (2006)
|
10.1103/PhysRevA.74.030303
| null |
quant-ph
| null |
The basic idea of spin chain engineering for perfect quantum state transfer
(QST) is to find a set of coupling constants in the Hamiltonian, such that a
particular state initially encoded on one site will evolve freely to the
opposite site without any dynamical controls. The minimal possible evolution
time represents a speed limit for QST. We prove that the optimal solution is
the one simulating the precession of a spin in a static magnetic field. We also
argue that, at least for solid-state systems where interactions are local, it
is more realistic to characterize the computation power by the couplings than
the initial energy.
|
[
{
"version": "v1",
"created": "Tue, 21 Mar 2006 02:18:25 GMT"
},
{
"version": "v2",
"created": "Tue, 2 May 2006 04:23:17 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Yung",
"Man-Hong",
""
]
] |
quant-ph/0603180
|
Fabiano Sutter de Oliveira
|
Fabiano Sutter de Oliveira
|
Factorization of large numbers and the suggestion of an algorithm
|
9 pages, 1 figure
| null | null | null |
quant-ph
| null |
In this paper, we intend to present a new algorithm to factorize large
numbers. According to the algorithm proposed here, we prove that there is a
common factor between p and q. With this procedure, the time of factorization
considerably decreases. The algorithm is based on a graphic representation and,
when the corresponding graph is drawn, coordinate pairs will originate two
straight lines that intercept one another. These coordinate pairs are formed by
prime numbers in the x-axis, and factors in the y-axis, including the factor in
common.
|
[
{
"version": "v1",
"created": "Tue, 21 Mar 2006 03:30:13 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"de Oliveira",
"Fabiano Sutter",
""
]
] |
quant-ph/0603181
|
Mehmet Ko\c{c}ak
|
B. Gonul
|
A search on the Klein-Gordon equation
|
8 pages, no figures
|
CHIN. PHYS.LETT. 23 (2006) 2640
|
10.1088/0256-307X/23/10/005
| null |
quant-ph
| null |
The s-wave Klein-Gordon equation for the bound states is separated in two
parts to see clearly the relativistic contributions to the solution in the
non-relativistic limit. The reliability of the model is discussed with the
specifically chosen two examples.
|
[
{
"version": "v1",
"created": "Tue, 21 Mar 2006 09:46:15 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Gonul",
"B.",
""
]
] |
quant-ph/0603182
|
Andrea Aiello
|
A. Aiello, G. Puentes, D. Voigt, and J. P. Woerdman
|
Maximally entangled mixed states made easy
|
6 pages, 3 figures
| null | null | null |
quant-ph
| null |
We show that it is possible to achieve maximally entangled mixed states of
two qubits from the singlet state via the action of local non-trace-preserving
quantum channels. Moreover, we present a simple, feasible linear optical
implementation of one of such channels.
|
[
{
"version": "v1",
"created": "Tue, 21 Mar 2006 12:14:24 GMT"
},
{
"version": "v2",
"created": "Thu, 6 Apr 2006 08:36:13 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Aiello",
"A.",
""
],
[
"Puentes",
"G.",
""
],
[
"Voigt",
"D.",
""
],
[
"Woerdman",
"J. P.",
""
]
] |
quant-ph/0603183
|
Diogenes Galetti
|
D. Galetti
|
Quantum description of spin tunneling in magnetic molecules: a new view
|
26 pages, 7 figures, submitted to Physica A
| null | null | null |
quant-ph
| null |
Starting from a phenomenological Hamiltonian originally written in terms of
angular momentum operators we derive a new quantum angle-based Hamiltonian that
allows for a discussion on the quantum spin tunneling. The study of the
applicability of the present approach, carried out in calculations with a
soluble quasi-spin model, shows that we are allowed to use our method in the
description of physical systems such as the Mn12-acetate molecule, as well as
the octanuclear iron cluster, Fe8, in a reliable way. With the present
description the interpretation of the spin tunneling is seen to be direct, the
spectra and energy barriers of those systems are obtained, and it is shown that
they agree with the experimental ones.
|
[
{
"version": "v1",
"created": "Tue, 21 Mar 2006 14:37:40 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Galetti",
"D.",
""
]
] |
quant-ph/0603184
|
Igor Jex
|
J. Novotny, G. Alber, I. Jex
|
Completely positive covariant two-qubit quantum processes and optimal
quantum NOT operations for entangled qubit pairs
|
14 pages, 2 figures
| null |
10.1103/PhysRevA.73.062311
| null |
quant-ph
| null |
The structure of all completely positive quantum operations is investigated
which transform pure two-qubit input states of a given degree of entanglement
in a covariant way. Special cases thereof are quantum NOT operations which
transform entangled pure two-qubit input states of a given degree of
entanglement into orthogonal states in an optimal way. Based on our general
analysis all covariant optimal two-qubit quantum NOT operations are determined.
In particular, it is demonstrated that only in the case of maximally entangled
input states these quantum NOT operations can be performed perfectly.
|
[
{
"version": "v1",
"created": "Tue, 21 Mar 2006 16:51:20 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Novotny",
"J.",
""
],
[
"Alber",
"G.",
""
],
[
"Jex",
"I.",
""
]
] |
quant-ph/0603185
|
Thomas Salzburger
|
Thomas Salzburger Helmut Ritsch
|
Lasing and cooling in a hot cavity
|
11 pages, 6 figures
| null |
10.1103/PhysRevA.74.033806
| null |
quant-ph
| null |
We present a microscopic laser model for many atoms coupled to a single
cavity mode, including the light forces resulting from atom-field momentum
exchange. Within a semiclassical description, we solve the equations for atomic
motion and internal dynamics to obtain analytic expressions for the optical
potential and friction force seen by each atom. When optical gain is maximum at
frequencies where the light field extracts kinetic energy from the atomic
motion, the dynamics combines optical lasing and motional cooling. From the
corresponding momentum diffusion coefficient we predict sub-Doppler
temperatures in the stationary state. This generalizes the theory of cavity
enhanced laser cooling to active cavity systems. We identify the gain induced
reduction of the effective resonator linewidth as key origin for the faster
cooling and lower temperatures, which implys that a bad cavity with a gain
medium can replace a high-Q cavity. In addition, this shows the importance of
light forces for gas lasers in the low-temperature limit, where atoms can
arrange in a periodic pattern maximizing gain and counteracting spatial hole
burning. Ultimately, in the low temperature limit, such a setup should allow to
combine optical lasing and atom lasing in single device.
|
[
{
"version": "v1",
"created": "Tue, 21 Mar 2006 19:17:15 GMT"
}
] | 2007-12-18T00:00:00 |
[
[
"Ritsch",
"Thomas Salzburger Helmut",
""
]
] |
quant-ph/0603186
|
Mattias Marklund
|
M. Marklund, B. Eliasson, P. K. Shukla, L. Stenflo, M. E. Dieckmann,
and M. Parviainen
|
Electrostatic pair creation and recombination in quantum plasmas
|
4 pages, 3 figures, to appear in JETP Letters
|
JETP Lett. 83, 313, 2006
|
10.1134/S0021364006080030
| null |
quant-ph
| null |
The collective production of electron-positron pairs by electrostatic waves
in quantum plasmas is investigated. In particular, a semi-classical governing
set of equation for a self-consistent treatment of pair creation by the
Schwinger mechanism in a quantum plasma is derived.
|
[
{
"version": "v1",
"created": "Tue, 21 Mar 2006 20:19:02 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Marklund",
"M.",
""
],
[
"Eliasson",
"B.",
""
],
[
"Shukla",
"P. K.",
""
],
[
"Stenflo",
"L.",
""
],
[
"Dieckmann",
"M. E.",
""
],
[
"Parviainen",
"M.",
""
]
] |
quant-ph/0603187
|
Pavel Yu. Moshin
|
B.L. Voronov, D.M. Gitman, I.V. Tyutin
|
Self-adjoint differential operators assosiated with self-adjoint
differential expressions
|
91 pages
| null | null |
Publicacao IFUSP-1619/2006
|
quant-ph hep-th math-ph math.MP
| null |
Considerable attention has been recently focused on quantum-mechanical
systems with boundaries and/or singular potentials for which the construction
of physical observables as self-adjoint (s.a.) operators is a nontrivial
problem. We present a comparative review of various methods of specifying
ordinary s.a. differential operators generated by formally s.a. differential
expressions based on the general theory of s.a. extensions of symmetric
operators. The exposition is untraditional and is based on the concept of
asymmetry forms generated by adjoint operators. The main attention is given to
a specification of s.a. extensions by s.a. boundary conditions. All the methods
are illustrated by examples of quantum-mechanical observables like momentum and
Hamiltonian. In addition to the conventional methods, we propose a possible
alternative way of specifying s.a. differential operators by explicit s.a.
boundary conditions that generally have an asymptotic form for singular
boundaries. A comparative advantage of the method is that it allows avoiding an
evaluation of deficient subspaces and deficiency indices. The effectiveness of
the method is illustrated by a number of examples of quantum-mechanical
observables.
|
[
{
"version": "v1",
"created": "Tue, 21 Mar 2006 21:24:39 GMT"
},
{
"version": "v2",
"created": "Thu, 23 Mar 2006 22:15:07 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Voronov",
"B. L.",
""
],
[
"Gitman",
"D. M.",
""
],
[
"Tyutin",
"I. V.",
""
]
] |
quant-ph/0603188
|
Farhan Saif
|
Shahid Iqbal, Qurat-ul-Ann and Farhan Saif
|
Quantum Recurrences in Driven Power-law Potentials
| null | null |
10.1016/j.physleta.2006.03.046
| null |
quant-ph
| null |
The recurrence phenomena of an initially well localized wave packet are
studied in periodically driven power-law potentials. For our general study we
divide the potentials in two kinds, namely tightly binding and loosely binding
potentials. In the presence of an external periodically modulating force, these
potentials may exhibit classical and quantum chaos. The dynamics of a quantum
wave packet in the modulated potentials displays recurrences at various time
scales. We develop general analytical relations for these times and discuss
their parametric dependence.
|
[
{
"version": "v1",
"created": "Wed, 22 Mar 2006 01:20:13 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Iqbal",
"Shahid",
""
],
[
"Qurat-ul-Ann",
"",
""
],
[
"Saif",
"Farhan",
""
]
] |
quant-ph/0603189
|
Dominic William Berry
|
Dominic W. Berry and Howard M. Wiseman
|
Adaptive phase measurements for narrowband squeezed beams
|
13 pages, 7 figures
|
Phys. Rev. A 73, 063824 (2006)
|
10.1103/PhysRevA.73.063824
| null |
quant-ph
| null |
We have previously [Phys. Rev. A 65, 043803 (2002)] analyzed adaptive
measurements for estimating the continuously varying phase of a coherent beam,
and a broadband squeezed beam. A real squeezed beam must have finite photon
flux N and hence can be significantly squeezed only over a limited frequency
range. In this paper we analyze adaptive phase measurements of this type for a
realistic model of a squeezed beam. We show that, provided it is possible to
suitably choose the parameters of the beam, a mean-square phase uncertainty
scaling as (N/kappa)^{-5/8} is possible, where kappa is the linewidth of the
beam resulting from the fluctuating phase. This is an improvement over the
(N/kappa)^{-1/2} scaling found previously for coherent beams. In the
experimentally realistic case where there is a limit on the maximum squeezing
possible, the variance will be reduced below that for coherent beams, though
the scaling is unchanged.
|
[
{
"version": "v1",
"created": "Wed, 22 Mar 2006 07:17:30 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Berry",
"Dominic W.",
""
],
[
"Wiseman",
"Howard M.",
""
]
] |
quant-ph/0603190
|
Nan-yow Chen
|
Zheng-Yao Su
|
A Scheme of Cartan Decomposition for su(N)
|
An extension of the talk in Annual Conf. PSROC 2006
| null | null | null |
quant-ph
| null |
A scheme to perform the Cartan decomposition for the Lie algebra su(N) of
arbitrary finite dimensions is introduced. The schme is based on two algebraic
structures, the conjugate partition and the quotient algebra, that are easily
generated by a Cartan subalgebra and generally exist in su(N). In particular,
the Lie algebras su(2^p) and every su(2^{p-1} < N < 2^p) share the isomorphic
structure of the quotient algebra. This structure enables an efficient
algorithm for the recursive and exhaustive construction of Cartan
decompositions. Further with the scheme, a unitary transformation in SU(N) can
be recursively decomposed into a product of certain designated operators, e.g.,
local and nonlocal gates. Such a recursive decomposition of a transformation
implies an evolution path on the manifold of the group.
|
[
{
"version": "v1",
"created": "Wed, 22 Mar 2006 10:53:53 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Su",
"Zheng-Yao",
""
]
] |
quant-ph/0603191
|
Pascal Degiovanni
|
Tristan Meunier (KI-NANO), Arnaud Le Diffon (Phys-ENS), Cl\'ement
Rueff (Phys-ENS), Pascal Degiovanni (Phys-ENS), Jean-Michel Raimond (LKB -
Lhomond)
|
Entanglement and decoherence of N atoms and a mesoscopic field in a
cavity
|
13 figures
|
Physical Review A 74 (2006) 033802
|
10.1103/PhysRevA.74.033802
| null |
quant-ph cond-mat.mes-hall
| null |
We investigate the behavior of N atoms resonantly coupled to a single
electromagnetic field mode sustained by a high quality cavity, containing a
mesoscopic coherent field. We show with a simple effective hamiltonian model
that the strong coupling between the cavity and the atoms produces an
atom-field entangled state, involving N+1 nearly-coherent components slowly
rotating at different paces in the phase plane. The periodic overlap of these
components results in a complex collapse and revival pattern for the Rabi
oscillation. We study the influence of decoherence due to the finite cavity
quality factor. We propose a simple analytical model, based on the Monte Carlo
approach to relaxation. We compare its predictions with exact calculations and
show that these interesting effects could realistically be observed on a two or
three atoms sample in a 15 photons field with circular Rydberg atoms and
superconducting cavities.
|
[
{
"version": "v1",
"created": "Wed, 22 Mar 2006 13:09:01 GMT"
},
{
"version": "v2",
"created": "Mon, 11 Sep 2006 09:04:31 GMT"
}
] | 2016-08-16T00:00:00 |
[
[
"Meunier",
"Tristan",
"",
"KI-NANO"
],
[
"Diffon",
"Arnaud Le",
"",
"Phys-ENS"
],
[
"Rueff",
"Clément",
"",
"Phys-ENS"
],
[
"Degiovanni",
"Pascal",
"",
"Phys-ENS"
],
[
"Raimond",
"Jean-Michel",
"",
"LKB -\n Lhomond"
]
] |
quant-ph/0603192
|
Matthias Staudt U.
|
Matthias U. Staudt, Sara R. Hastings-Simon, Mikael Afzelius, Didier
Jaccard, Wolfgang Tittel, Nicolas Gisin
|
Investigations of Optical Coherence Properties in an Erbium-doped
Silicate Fiber for Quantum State Storage
| null |
Optics Communications 266 (2006) 720-726
|
10.1016/j.optcom.2006.05.007
| null |
quant-ph
| null |
We studied optical coherence properties of the 1.53 $\mu$m telecommunication
transition in an Er$^{3+}$-doped silicate optical fiber through spectral
holeburning and photon echoes. We find decoherence times of up to 3.8 $\mu$s at
a magnetic field of 2.2 Tesla and a temperature of 150 mK. A strong
magnetic-field dependent optical dephasing was observed and is believed to
arise from an interaction between the electronic Er$^{3+}$ spin and the
magnetic moment of tunneling modes in the glass. Furthermore, we observed
fine-structure in the Erbium holeburning spectrum originating from
superhyperfine interaction with $^{27}$Al host nuclei. Our results show that
Er$^{3+}$-doped silicate fibers are promising material candidates for quantum
state storage.
|
[
{
"version": "v1",
"created": "Wed, 22 Mar 2006 13:57:00 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Staudt",
"Matthias U.",
""
],
[
"Hastings-Simon",
"Sara R.",
""
],
[
"Afzelius",
"Mikael",
""
],
[
"Jaccard",
"Didier",
""
],
[
"Tittel",
"Wolfgang",
""
],
[
"Gisin",
"Nicolas",
""
]
] |
quant-ph/0603193
|
Stefan Yoshi Buhmann
|
Stefan Yoshi Buhmann, Hassan Safari, Dirk-Gunnar Welsch, and Ho Trung
Dung
|
Microscopic origin of Casimir-Polder forces
|
10 pages, 0 figures
|
Open Systems and Information Dynamics 13 (4), 427 (2006)
|
10.1007/s11080-006-9024-0
| null |
quant-ph
| null |
We establish a general relation between dispersion forces. First, based on
QED in causal media, leading-order perturbation theory is used to express both
the single-atom Casimir-Polder and the two-atom van der Waals potentials in
terms of the atomic polarizabilities and the Green tensor for the body-assisted
electromagnetic field. Endowed with this geometry-independent framework, we
then employ the Born expansion of the Green tensor together with the
Clausius-Mosotti relation to prove that the macroscopic Casimir-Polder
potential of an atom in the presence of dielectric bodies is due to an infinite
sum of its microscopic many-atom van der Waals interactions with the atoms
comprising the bodies. This theorem holds for inhomogeneous, dispersing, and
absorbing bodies of arbitrary shapes and arbitrary atomic composition on an
arbitrary background of additional magnetodielectric bodies.
|
[
{
"version": "v1",
"created": "Wed, 22 Mar 2006 13:45:36 GMT"
},
{
"version": "v2",
"created": "Tue, 12 Jun 2007 08:12:34 GMT"
}
] | 2007-06-12T00:00:00 |
[
[
"Buhmann",
"Stefan Yoshi",
""
],
[
"Safari",
"Hassan",
""
],
[
"Welsch",
"Dirk-Gunnar",
""
],
[
"Dung",
"Ho Trung",
""
]
] |
quant-ph/0603194
|
Sara Hastings-Simon
|
Sara R. Hastings-Simon, Matthias U. Staudt, Mikael Afzelius, Pascal
Baldi, Didier Jaccard, Wolfgang Tittel, Nicolas Gisin
|
Controlled Stark shifts in Er$^{3+}$-doped crystalline and amorphous
waveguides for quantum state storage
|
4 pages, 2 figures v2. typo in formula corrected
| null |
10.1016/j.optcom.2006.05.003
| null |
quant-ph
| null |
We present measurements of the linear Stark effect on the $^{4}$I$_{15/2}
\to$ $^{4}$I$_{13/2}$ transition in an Er$^{3+}$-doped proton-exchanged
LiNbO$_{3}$ crystalline waveguide and an Er$^{3+}$-doped silicate fiber. The
measurements were made using spectral hole burning techniques at temperatures
below 4 K. We measured an effective Stark coefficient
$(\Delta\mu_{e}\chi)/(h)=25\pm1$kHz/Vcm$^{-1}$ in the crystalline waveguide and
$(\bar{\Delta\mu_{e}}\chi)/(h)=15\pm1$kHz/Vcm$^{-1}$ in the silicate fiber.
These results confirm the potential of Erbium doped waveguides for quantum
state storage based on controlled reversible inhomogeneous broadening.
|
[
{
"version": "v1",
"created": "Wed, 22 Mar 2006 13:46:34 GMT"
},
{
"version": "v2",
"created": "Wed, 29 Mar 2006 08:15:20 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Hastings-Simon",
"Sara R.",
""
],
[
"Staudt",
"Matthias U.",
""
],
[
"Afzelius",
"Mikael",
""
],
[
"Baldi",
"Pascal",
""
],
[
"Jaccard",
"Didier",
""
],
[
"Tittel",
"Wolfgang",
""
],
[
"Gisin",
"Nicolas",
""
]
] |
quant-ph/0603195
|
Daniel Segal
|
J.R. Castrejon-Pita, H. Ohadi, D.R. Crick, D.F.A. Winters, D.M. Segal
and R.C. Thompson
|
Novel designs for Penning ion traps
|
11 pages, 10 figures
| null | null | null |
quant-ph
| null |
We present a number of alternative designs for Penning ion traps suitable for
quantum information processing (QIP) applications with atomic ions. The first
trap design is a simple array of long straight wires which allows easy optical
access. A prototype of this trap has been built to trap Ca+ and a simple
electronic detection scheme has been employed to demonstrate the operation of
the trap. Another trap design consists of a conducting plate with a hole in it
situated above a continuous conducting plane. The final trap design is based on
an array of pad electrodes. Although this trap design lacks the open geometry
of the traps described above, the pad design may prove useful in a hybrid
scheme in which information processing and qubit storage take place in
different types of trap. The behaviour of the pad traps is simulated
numerically and techniques for moving ions rapidly between traps are discussed.
Future experiments with these various designs are discussed. All of the designs
lend themselves to the construction of multiple trap arrays, as required for
scalable ion trap QIP.
|
[
{
"version": "v1",
"created": "Wed, 22 Mar 2006 14:50:14 GMT"
}
] | 2022-04-26T00:00:00 |
[
[
"Castrejon-Pita",
"J. R.",
""
],
[
"Ohadi",
"H.",
""
],
[
"Crick",
"D. R.",
""
],
[
"Winters",
"D. F. A.",
""
],
[
"Segal",
"D. M.",
""
],
[
"Thompson",
"R. C.",
""
]
] |
quant-ph/0603196
|
Luca Marinatto
|
GianCarlo Ghirardi and Luca Marinatto
|
Greenberger-Horne-Zeilinger argument of nonlocality without inequalities
for mixed states
|
8 pages, RevTex; added references, corrected typos
|
Physical Review A 74, 1 (2006)
|
10.1103/PhysRevA.74.022101
| null |
quant-ph
| null |
We generalize the Greenberger-Horne-Zeilinger nonlocality without
inequalities argument to cover the case of arbitrary mixed statistical
operators associated to three-qubits quantum systems. More precisely, we
determine the radius of a ball (in the trace distance topology) surrounding the
pure GHZ state and containing arbitrary mixed statistical operators which
cannot be described by any local and realistic hidden variable model and which
are, as a consequence, noncompletely separable. As a practical application, we
focus on certain one-parameter classes of mixed states which are commonly
considered in the experimental realization of the original GHZ argument and
which result from imperfect preparations of the pure GHZ state. In these cases
we determine for which values of the parameter controlling the noise a
nonlocality argument can still be exhibited, despite the mixedness of the
considered states. Moreover, the effect of the imperfect nature of measurement
processes is discussed.
|
[
{
"version": "v1",
"created": "Wed, 22 Mar 2006 15:14:39 GMT"
},
{
"version": "v2",
"created": "Wed, 19 Jul 2006 13:15:02 GMT"
},
{
"version": "v3",
"created": "Tue, 8 Aug 2006 14:31:39 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Ghirardi",
"GianCarlo",
""
],
[
"Marinatto",
"Luca",
""
]
] |
quant-ph/0603197
|
Aurelien Dantan
|
Aurelien Dantan (LCFIO), Jean Cviklinski (LKB - Jussieu), Elisabeth
Giacobino (LKB - Jussieu), Michel Pinard (LKB - Jussieu)
|
Spin-Squeezing and Light Entanglement in Coherent Population Trapping
|
4 pages, 5 figures
|
Physical Review Letters 97 (2006) 023605
|
10.1103/PhysRevLett.97.023605
| null |
quant-ph
| null |
We show that high squeezing and entanglement can be generated at the output
of a cavity containing atoms interacting with two fields in a Coherent
Population Trapping situation, on account of a non-linear Faraday effect
experienced by the fields close to a dark-state resonance in a cavity.
Moreover, the cavity provides a feedback mechanism allowing to reduce the
quantum fluctuations of the ground state spin, resulting in strong steady state
spin-squeezing.
|
[
{
"version": "v1",
"created": "Wed, 22 Mar 2006 16:35:03 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Dantan",
"Aurelien",
"",
"LCFIO"
],
[
"Cviklinski",
"Jean",
"",
"LKB - Jussieu"
],
[
"Giacobino",
"Elisabeth",
"",
"LKB - Jussieu"
],
[
"Pinard",
"Michel",
"",
"LKB - Jussieu"
]
] |
quant-ph/0603198
|
Gennadiy Burlak
|
G.Burlak, A.Klimov
|
Asymmetrical two-atom entanglement in a coated microsphere
| null | null |
10.1016/j.physleta.2006.08.004
| null |
quant-ph
| null |
We study evolution of entanglement of two two-level atoms placed inside a
multilayered microsphere. We show that due to inhomogeneity of the field modes
this entanglement essentially depends on the atomic positions (asymmetrical
entanglement) and also on the detuning between the atomic transitions and field
frequencies. The robust and complete entanglement can be achieved even in the
resonant case when the atoms have different effective coupling constants, and
it can be extended in time if the detuning is large enough. We study
analytically the lossless case and estimate numerically the effect of
dissipative processes.
|
[
{
"version": "v1",
"created": "Wed, 22 Mar 2006 18:43:17 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Burlak",
"G.",
""
],
[
"Klimov",
"A.",
""
]
] |
quant-ph/0603199
|
Lawrence Ioannou
|
Lawrence M. Ioannou
|
Computational complexity of the quantum separability problem
| null |
Quantum Information and Computation, Vol. 7, No. 4 (2007) 335-370
| null | null |
quant-ph cs.CC
| null |
Ever since entanglement was identified as a computational and cryptographic
resource, researchers have sought efficient ways to tell whether a given
density matrix represents an unentangled, or separable, state. This paper gives
the first systematic and comprehensive treatment of this (bipartite) quantum
separability problem, focusing on its deterministic (as opposed to randomized)
computational complexity. First, I review the one-sided tests for separability,
paying particular attention to the semidefinite programming methods. Then, I
discuss various ways of formulating the quantum separability problem, from
exact to approximate formulations, the latter of which are the paper's main
focus. I then give a thorough treatment of the problem's relationship with the
complexity classes NP, NP-complete, and co-NP. I also discuss extensions of
Gurvits' NP-hardness result to strong NP-hardness of certain related problems.
A major open question is whether the NP-contained formulation (QSEP) of the
quantum separability problem is Karp-NP-complete; QSEP may be the first natural
example of a problem that is Turing-NP-complete but not Karp-NP-complete.
Finally, I survey all the proposed (deterministic) algorithms for the quantum
separability problem, including the bounded search for symmetric extensions
(via semidefinite programming), based on the recent quantum de Finetti theorem;
and the entanglement-witness search (via interior-point algorithms and global
optimization). These two algorithms have the lowest complexity, with the latter
being the best under advice of asymptotically optimal point-coverings of the
sphere.
|
[
{
"version": "v1",
"created": "Wed, 22 Mar 2006 18:54:54 GMT"
},
{
"version": "v2",
"created": "Mon, 27 Mar 2006 17:44:43 GMT"
},
{
"version": "v3",
"created": "Tue, 28 Mar 2006 10:02:20 GMT"
},
{
"version": "v4",
"created": "Tue, 18 Jul 2006 10:06:50 GMT"
},
{
"version": "v5",
"created": "Fri, 21 Jul 2006 15:09:55 GMT"
},
{
"version": "v6",
"created": "Thu, 18 Jan 2007 16:42:31 GMT"
},
{
"version": "v7",
"created": "Wed, 31 Jan 2007 13:20:02 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Ioannou",
"Lawrence M.",
""
]
] |
quant-ph/0603200
|
Gondran Alexandre
|
Michel Gondran and Alexandre Gondran
|
A Crucial Experiment To Test The Broglie-Bohm Trajectories For
Indistinguishable Particles
|
5 pages, 5 figures, submitted to Physical Review A
| null | null | null |
quant-ph
| null |
The standard quantum theory has not taken into account the size of quantum
particles, the latter being implicitly treated as material points. The recent
interference experiments of Zeilinger [3] with large molecules like fullerenes
and the thought experiments of Bozic et al [7] with asymmetrical Young slits
make it possible today to take into account the particle size.
We present here a complete study of this phenomenon where our simulations
show differences between the particles density after the slits and the modulus
square of the wave function. Then we propose a crucial experiment that allows
us to reconsider the wave-particle duality and to test the existence of the
Broglie-Bohm trajectories for indistinguishable particles.
|
[
{
"version": "v1",
"created": "Wed, 22 Mar 2006 21:22:20 GMT"
},
{
"version": "v2",
"created": "Thu, 30 Mar 2006 08:49:52 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Gondran",
"Michel",
""
],
[
"Gondran",
"Alexandre",
""
]
] |
quant-ph/0603201
|
Marek Zukowski
|
Marek Zukowski
|
On tight multiparty Bell inequalities for many settings
|
to be published in Quant. Inf. Proc., an extended version will be
given soon
| null | null | null |
quant-ph
| null |
A derivation method is given which leads to a series of tight Bell
inequalities for experiments involving N parties, with binary observables, and
three possible local settings. The approach can be generalized to more
settings. Ramifications are presented.
|
[
{
"version": "v1",
"created": "Wed, 22 Mar 2006 21:34:20 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Zukowski",
"Marek",
""
]
] |
quant-ph/0603202
|
Olaf Dreyer
|
Olaf Dreyer
|
Emergent Probabilities in Quantum Mechanics
| null | null | null | null |
quant-ph hep-th
| null |
The transition from the quantum to the classical is governed by randomizing
devices (RD), i.e., dynamical systems that are very sensitive to the
environment. We show that, in the presence of RDs, the usual arguments based on
the linearity of quantum mechanics that lead to the measurement problem do not
apply. RDs are the source of probabilities in quantum mechanics. Hence, the
reason for probabilities in quantum mechanics is the same as the reason for
probabilities in other parts of physics, namely our ignorance of the state of
the environment. This should not be confused with decoherence. The environment
here plays several, equally important roles: it is the dump for energy and
entropy of the RD, it puts the RD close to its transition point and it is the
reason for probabilities in quantum mechanics. We show that, even though the
state of the environment is unknown, the probabilities can be calculated and
are given by the Born rule. We then discuss what this view of quantum mechanics
means for the search of a quantum theory of gravity.
|
[
{
"version": "v1",
"created": "Wed, 22 Mar 2006 21:40:10 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Dreyer",
"Olaf",
""
]
] |
quant-ph/0603203
|
Alexander E. Meyerovich
|
A. E. Meyerovich (University of Rhode Island), V. V. Nesvizhevsky
(ILL, Grenoble)
|
Gravitational quantum states of neutrons in a rough waveguide
|
48 pages, 14 figures
| null |
10.1103/PhysRevA.73.063616
| null |
quant-ph
| null |
A theory of gravitational quantum states of ultracold neutrons in waveguides
with absorbing/scattering walls is presented. The theory covers recent
experiments in which the ultracold neutrons were beamed between a mirror and a
rough scatterer/absorber. The analysis is based on a recently developed theory
of quantum transport along random rough walls which is modified in order to
include leaky (absorbing) interfaces and, more importantly, the low-amplitude
high-aperture roughness. The calculations are focused on a regime when the
direct transitions into the continuous spectrum above the absorption threshold
dominate the depletion of neutrons from the gravitational states and are more
efficient than the processes involving the intermediate states. The theoretical
results for the neutron count are sensitive to the correlation radius (lateral
size) of surface inhomogeneities and to the ratio of the particle energy to the
absorption threshold in a weak roughness limit. The main impediment for
observation of the higher gravitational states is the "overhang" of the
particle wave functions which can be overcome only by use scatterers with
strong roughness. In general, the strong roughness with high amplitude is
preferable if one wants just to detect the individual gravitational states,
while the strong roughness experiments with small amplitude and high aperture
are preferable for the quantitative analysis of the data. We also discuss the
ways to further improve the accuracy of calculations and to optimize the
experimental regime.
|
[
{
"version": "v1",
"created": "Wed, 22 Mar 2006 22:38:57 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Meyerovich",
"A. E.",
"",
"University of Rhode Island"
],
[
"Nesvizhevsky",
"V. V.",
"",
"ILL, Grenoble"
]
] |
quant-ph/0603204
|
Dafa Li
|
D. Li, J. P. Chen, X. Li, H. Huang, X. Li
|
Performance of Equal Phase-Shift Search for One Iteration
|
10 pages, 4 figures
|
EPJD (European physical journal D) vol. 45, (2007) pp.335-340
|
10.1140/epjd/e2007-00247-9
| null |
quant-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Grover presented the phase-shift search by replacing the selective inversions
by selective phase shifts of $\pi /3$. In this paper, we investigate the
phase-shift search with general equal phase shifts. We show that for small
uncertainties, the failure probability of the Phase-$\pi /3$ search is smaller
than the general phase-shift search and for large uncertainties, the success
probability of the large phase-shift search is larger than the Phase-$\pi /3$
search. Therefore, the large phase-shift search is suitable for large-size of
databases.
|
[
{
"version": "v1",
"created": "Thu, 23 Mar 2006 03:35:48 GMT"
},
{
"version": "v2",
"created": "Sat, 6 Jan 2007 04:01:07 GMT"
},
{
"version": "v3",
"created": "Wed, 16 Dec 2009 02:36:54 GMT"
}
] | 2009-12-16T00:00:00 |
[
[
"Li",
"D.",
""
],
[
"Chen",
"J. P.",
""
],
[
"Li",
"X.",
""
],
[
"Huang",
"H.",
""
],
[
"Li",
"X.",
""
]
] |
quant-ph/0603205
|
Ramazan Sever
|
Sameer M. Ikhdair and Ramazan Sever
|
A perturbative treatment for the bound states of the Hellmann potential
|
25 pages
|
THEOCHEM 809, 103 (2007)
| null | null |
quant-ph
| null |
A new approximation formalism is applied to study the bound states of the
Hellmann potential, which represents the superposition of the attractive
Coulomb potential $-a/r$ and the Yukawa potential $b\exp (-\delta r)/r$ of
arbitrary strength $b$ and screening parameter $\delta $. Although the analytic
expressions for the energy eigenvalues $E_{n,l\text{}}$ yield quite accurate
results for a wide range of $n,\ell $ in the limit of very weak screening, the
results become gradually worse as the strength $b$ and the screening
coefficient $\delta $ increase. This is because that the expansion parameter is
not sufficiently small enough to guarantee the convergence of the expansion
series for the energy levels.
|
[
{
"version": "v1",
"created": "Thu, 23 Mar 2006 09:12:51 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Ikhdair",
"Sameer M.",
""
],
[
"Sever",
"Ramazan",
""
]
] |
quant-ph/0603206
|
Metod Saniga
|
Metod Saniga (ASTRINSTSAV), Michel Planat (FCEMTO), Milan Minarovjech
(ASTRINSTSAV)
|
The Projective Line Over the Finite Quotient Ring GF(2)[$x$]/$< x^{3} -
x>$ and Quantum Entanglement II. The Mermin "Magic" Square/Pentagram
|
6 pages, 5 figures
|
Theoretical and Mathematical Physics 151 (2007) 625-631
|
10.1007/s11232-007-0049-5
| null |
quant-ph math-ph math.MP
| null |
In 1993, Mermin (Rev. Mod. Phys. 65, 803--815) gave lucid and strikingly
simple proofs of the Bell-Kochen-Specker (BKS) theorem in Hilbert spaces of
dimensions four and eight by making use of what has since been referred to as
the Mermin(-Peres) "magic square" and the Mermin pentagram, respectively. The
former is a $3 \times 3$ array of nine observables commuting pairwise in each
row and column and arranged so that their product properties contradict those
of the assigned eigenvalues. The latter is a set of ten observables arranged in
five groups of four lying along five edges of the pentagram and characterized
by similar contradiction. An interesting one-to-one correspondence between the
operators of the Mermin-Peres square and the points of the projective line over
the product ring ${\rm GF}(2) \otimes \rm{GF}(2)$ is established. Under this
mapping, the concept "mutually commuting" translates into "mutually distant"
and the distinguishing character of the third column's observables has its
counterpart in the distinguished properties of the coordinates of the
corresponding points, whose entries are both either zero-divisors, or units.
The ten operators of the Mermin pentagram answer to a specific subset of points
of the line over GF(2)[$x$]/$<x^{3} - x>$. The situation here is, however, more
intricate as there are two different configurations that seem to serve equally
well our purpose. The first one comprises the three distinguished points of the
(sub)line over GF(2), their three "Jacobson" counterparts and the four points
whose both coordinates are zero-divisors; the other features the neighbourhood
of the point ($1, 0$) (or, equivalently, that of ($0, 1$)). Some other ring
lines that might be relevant for BKS proofs in higher dimensions are also
mentioned.
|
[
{
"version": "v1",
"created": "Thu, 23 Mar 2006 10:01:33 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Saniga",
"Metod",
"",
"ASTRINSTSAV"
],
[
"Planat",
"Michel",
"",
"FCEMTO"
],
[
"Minarovjech",
"Milan",
"",
"ASTRINSTSAV"
]
] |
quant-ph/0603207
|
Hrvoje Nikolic
|
H. Nikolic
|
Many-fingered time Bohmian mechanics
|
7 pages
| null | null | null |
quant-ph gr-qc hep-th
| null |
The many-fingered time (MFT) formulation of many-particle quantum mechanics
and quantum field theory is a natural framework that overcomes the problem of
"instantaneous collapse" in entangled systems that exhibit nonlocalities. The
corresponding Bohmian interpretation can also be formulated in terms of MFT
beables, which alleviates the problem of instantaneous action at a distance by
using an ontology that differs from that in the standard Bohmian
interpretation. The appearance of usual single-time particle-positions and
fields is recovered by quantum measurements.
|
[
{
"version": "v1",
"created": "Thu, 23 Mar 2006 11:17:26 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Nikolic",
"H.",
""
]
] |
quant-ph/0603208
|
Johannes Kofler
|
Johannes Kofler and Caslav Brukner
|
Entanglement distribution revealed by macroscopic observations
|
4 pages, 2 figures, revised and published version
|
Phys. Rev. A 74, 050304(R) (2006)
|
10.1103/PhysRevA.74.050304
| null |
quant-ph
| null |
What can we learn about entanglement between individual particles in
macroscopic samples by observing only the collective properties of the
ensembles? Using only a few experimentally feasible collective properties, we
establish an entanglement measure between two samples of spin-1/2 particles (as
representatives of two-dimensional quantum systems). This is a tight lower
bound for the average entanglement between all pairs of spins in general and is
equal to the average entanglement for a certain class of systems. We compute
the entanglement measures for explicit examples and show how to generalize the
method to more than two samples and multi-partite entanglement.
|
[
{
"version": "v1",
"created": "Thu, 23 Mar 2006 13:11:45 GMT"
},
{
"version": "v2",
"created": "Fri, 17 Nov 2006 10:38:42 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Kofler",
"Johannes",
""
],
[
"Brukner",
"Caslav",
""
]
] |
quant-ph/0603209
|
Pramod Joag
|
Ali Ahanj and Pramod Joag
|
Communication cost of simulating quantum correlations in a class of
integer spin singlet states
|
6 pages no figures sequential to quant-ph/0603053
| null | null | null |
quant-ph
| null |
We give a classical protocol to exactly simulate quantum correlations implied
by a spin $s$ singlet state for the infinite sequence of \textit{integer} spin
$s={1,4,13,...}$ satisfying $(2s+1)=3^{n}$,where $n$ is a positive integer.The
required amount of communication is found to increase as $log_{3}d^{2}$ where
$d=2s+1$ is the dimension of the spin $s$ Hilbert space.
|
[
{
"version": "v1",
"created": "Thu, 23 Mar 2006 14:59:45 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Ahanj",
"Ali",
""
],
[
"Joag",
"Pramod",
""
]
] |
quant-ph/0603210
|
Bin Shang
|
Bin Shang
|
A summary on two new algorithms for Grover's unsorted database search
problem
|
2 pages. LaTex revtex4. APS twocolumn
| null | null | null |
quant-ph
| null |
In this summary we discuss two new algorithms for Grover's unsorted database
search problem that claimed to have reached exponential speedup over Grover's
original algorithm. One is in the quantum setting with "power queries" that
allow for exponential reduction in the number of queries over Grover's original
algorithm with "bit queries". The other is to use "dubit queries" on a duality
computer - a new computing model uses a quantum system's wave-particle duality,
which is able to achieve even greater computing power and better capability
than existent quantum computers we have been discussing. We discuss the
shortages and difficulties of both schemes as well.
|
[
{
"version": "v1",
"created": "Thu, 23 Mar 2006 15:59:02 GMT"
},
{
"version": "v2",
"created": "Sat, 8 Apr 2006 06:56:45 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Shang",
"Bin",
""
]
] |
quant-ph/0603211
|
Hernando Efrain Caicedo Ortiz
|
H. E. Caicedo-Ortiz and S. T. Perez-Merchancano
|
Exchange Energy in Coupled Quantum Dots
|
4 pages, 4 figures, Accepted for publication in Brazilian Journal of
Physics
|
Brazilian Journal of Physics, vol. 36, no. 3B, September, 2006
|
10.1590/S0103-97332006000600020
| null |
quant-ph
| null |
In this work, the exchange energy J for a system of two laterally-coupled
quantum dots, each one with an electron, is calculated analytically and in a
detailed form, considering them as hydrogen-like atoms, under the
Heitler-London approach. The atomic orbitals, associated to each quantum dot,
are obtained from translation relations, as functions of the Fock-Darwin
states. Our results agree with the reported ones by Burkard, Loss and
DiVincenzo in their model of quantum gates based on quantum dots, as well as
with some recent experimental reports.
|
[
{
"version": "v1",
"created": "Thu, 23 Mar 2006 16:21:33 GMT"
},
{
"version": "v2",
"created": "Fri, 23 Jun 2006 03:00:11 GMT"
}
] | 2015-06-26T00:00:00 |
[
[
"Caicedo-Ortiz",
"H. E.",
""
],
[
"Perez-Merchancano",
"S. T.",
""
]
] |
quant-ph/0603212
|
Ra\'ul Oscar Vallejos
|
Raul O. Vallejos, P. R. del Santoro, and A. M. Ozorio de Almeida
|
Quantum baker maps with controlled-NOT coupling
|
8 pages
| null |
10.1088/0305-4470/39/18/028
| null |
quant-ph
| null |
The characteristic stretching and squeezing of chaotic motion is linearized
within the finite number of phase space domains which subdivide a classical
baker map. Tensor products of such maps are also chaotic, but a more
interesting generalized baker map arises if the stacking orders for the factor
maps are allowed to interact. These maps are readily quantized, in such a way
that the stacking interaction is entirely attributed to primary qubits in each
map, if each subsystem has power-of-two Hilbert space dimension. We here study
the particular example of two baker maps that interact via a controlled-not
interaction. Numerical evidence indicates that the control subspace becomes an
ideal Markovian environment for the target map in the limit of large Hilbert
space dimension.
|
[
{
"version": "v1",
"created": "Thu, 23 Mar 2006 16:52:57 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Vallejos",
"Raul O.",
""
],
[
"del Santoro",
"P. R.",
""
],
[
"de Almeida",
"A. M. Ozorio",
""
]
] |
quant-ph/0603213
|
Gustavo Garcia Rigolin
|
Goren Gordon, Gustavo Rigolin
|
Generalized Quantum State Sharing
|
4 pages, 2 figures, RevTex4, Published version
|
Phys. Rev. A 73, 062316 (2006)
|
10.1103/PhysRevA.73.062316
| null |
quant-ph
| null |
We present two quantum state sharing protocols where the channels are not
maximally entangled states. By properly choosing the measurement basis it is
possible to achieve unity fidelity transfer of the state if the parties
collaborate. We also show that contrary to the protocols where we have
maximally entangled channels these protocols are probabilistic. We then compare
the efficiency of both protocols and sketch the generalization of the protocols
to N parties.
|
[
{
"version": "v1",
"created": "Thu, 23 Mar 2006 17:25:06 GMT"
},
{
"version": "v2",
"created": "Tue, 13 Jun 2006 12:30:57 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Gordon",
"Goren",
""
],
[
"Rigolin",
"Gustavo",
""
]
] |
quant-ph/0603214
|
Mikio Kozuma
|
Takahito Tanimura, Daisuke Akamatsu, Yoshihiko Yokoi, Akira Furusawa,
and Mikio Kozuma
|
Generation of a squeezed vacuum resonant on Rubidium D_1 line with
periodically-poled KTiOPO_4
|
4 pages, 4 figures
|
Optics Letters 31, 2344 (2006).
|
10.1364/OL.31.002344
| null |
quant-ph
| null |
We report generation of a continuous-wave squeezed vacuum resonant on the Rb
D_1 line (795 nm) using periodically poled KTiOPO_4 (PPKTP) crystals. With a
frequency doubler and an optical parametric oscillator based on PPKTP crystals,
we observed a squeezing level of -2.75 +- 0.14 dB and an anti-squeezing level
of +7.00 +- 0.13 dB. This system could be utilized for demonstrating storage
and retrieval of the squeezed vacuum, which is important for the ultra-precise
measurement of atomic spins as well as quantum information processing.
|
[
{
"version": "v1",
"created": "Thu, 23 Mar 2006 18:05:40 GMT"
}
] | 2015-06-26T00:00:00 |
[
[
"Tanimura",
"Takahito",
""
],
[
"Akamatsu",
"Daisuke",
""
],
[
"Yokoi",
"Yoshihiko",
""
],
[
"Furusawa",
"Akira",
""
],
[
"Kozuma",
"Mikio",
""
]
] |
quant-ph/0603215
|
Gustavo Garcia Rigolin
|
Gustavo Rigolin, Thiago R. de Oliveira, Marcos C. de Oliveira
|
Operational Classification and Quantification of Multipartite Entangled
States
|
14 pages, RevTex4, published version
|
Phys. Rev. A 74, 022314 (2006)
|
10.1103/PhysRevA.74.022314
| null |
quant-ph
| null |
We formalize and extend an operational multipartite entanglement measure
introduced by T. R. Oliveira, G. Rigolin, and M. C. de Oliveira, Phys. Rev. A
73, 010305(R) (2006), through the generalization of global entanglement (GE)
[D. A. Meyer and N. R. Wallach, J. Math. Phys. 43, 4273 (2002)]. Contrarily to
GE the main feature of this measure lies in the fact that we study the mean
linear entropy of all possible partitions of a multipartite system. This allows
the construction of an operational multipartite entanglement measure which is
able to distinguish among different multipartite entangled states that GE
failed to discriminate. Furthermore, it is also maximum at the critical point
of the Ising chain in a transverse magnetic field, being thus able to detect a
quantum phase transition.
|
[
{
"version": "v1",
"created": "Thu, 23 Mar 2006 18:33:57 GMT"
},
{
"version": "v2",
"created": "Tue, 2 May 2006 18:51:12 GMT"
},
{
"version": "v3",
"created": "Mon, 21 Aug 2006 14:42:42 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Rigolin",
"Gustavo",
""
],
[
"de Oliveira",
"Thiago R.",
""
],
[
"de Oliveira",
"Marcos C.",
""
]
] |
quant-ph/0603216
|
Jean-Claude Garreau
|
Julien Chab\'e (PhLAM, CERLA), Hans Lignier (PhLAM, CERLA), Pascal
Szriftgiser (PhLAM, CERLA), Jean Claude Garreau (PhLAM, CERLA)
|
Improving Raman velocimetry of laser-cooled cesium atoms by
spin-polarization
|
12 pages, 6 figures, Elsevier style, to appear in Opt. Commun
|
Optics Communications 274, 1 (01/06/2007) 254-259
|
10.1016/j.optcom.2007.02.008
| null |
quant-ph cond-mat.other physics.atom-ph physics.optics
| null |
We study the peformances of Raman velocimetry applied to laser-cooled,
spin-polarized, cesium atoms. Atoms are optically pumped into the F=4, m=0
ground-state Zeeman sublevel, which is insensitive to magnetic perturbations.
High resolution Raman stimulated spectroscopy is shown to produce
Fourier-limited lines, allowing, in realistic experimental conditions, atomic
velocity selection to one-fiftieth of a recoil velocity.
|
[
{
"version": "v1",
"created": "Thu, 23 Mar 2006 18:34:06 GMT"
},
{
"version": "v2",
"created": "Sun, 4 Feb 2007 17:49:16 GMT"
}
] | 2016-08-16T00:00:00 |
[
[
"Chabé",
"Julien",
"",
"PhLAM, CERLA"
],
[
"Lignier",
"Hans",
"",
"PhLAM, CERLA"
],
[
"Szriftgiser",
"Pascal",
"",
"PhLAM, CERLA"
],
[
"Garreau",
"Jean Claude",
"",
"PhLAM, CERLA"
]
] |
quant-ph/0603217
|
Hartmut Haeffner
|
H. Haeffner, W. Haensel, C. F. Roos, J. Benhelm, D. Chek-al-kar, M.
Chwalla, T. Koerber, U. D. Rapol, M. Riebe, P. O. Schmidt, C. Becher, O.
G\"uhne, W. D\"ur, R. Blatt
|
Scalable multi-particle entanglement of trapped ions
| null |
Nature 438, 643-646 (2005)
|
10.1038/nature04279
| null |
quant-ph
| null |
Among the various kinds of entangled states, the 'W state' plays an important
role as its entanglement is maximally persistent and robust even under particle
loss. Such states are central as a resource in quantum information processing
and multiparty quantum communication. Here we report the scalable and
deterministic generation of four-, five-, six-, seven- and eight-particle
entangled states of the W type with trapped ions. We obtain the maximum
possible information on these states by performing full characterization via
state tomography, using individual control and detection of the ions. A
detailed analysis proves that the entanglement is genuine. The availability of
such multiparticle entangled states, together with full information in the form
of their density matrices, creates a test-bed for theoretical studies of
multiparticle entanglement. Independently, -Greenberger-Horne-Zeilinger-
entangled states with up to six ions have been created and analysed in Boulder.
|
[
{
"version": "v1",
"created": "Thu, 23 Mar 2006 18:41:24 GMT"
}
] | 2009-09-29T00:00:00 |
[
[
"Haeffner",
"H.",
""
],
[
"Haensel",
"W.",
""
],
[
"Roos",
"C. F.",
""
],
[
"Benhelm",
"J.",
""
],
[
"Chek-al-kar",
"D.",
""
],
[
"Chwalla",
"M.",
""
],
[
"Koerber",
"T.",
""
],
[
"Rapol",
"U. D.",
""
],
[
"Riebe",
"M.",
""
],
[
"Schmidt",
"P. O.",
""
],
[
"Becher",
"C.",
""
],
[
"Gühne",
"O.",
""
],
[
"Dür",
"W.",
""
],
[
"Blatt",
"R.",
""
]
] |
quant-ph/0603218
|
Martin Weitz
|
Leon Karpa and Martin Weitz
|
A Stern-Gerlach experiment for slow light
|
11 pages, 3 figures. Nature Physics 2, 332 (2006)
| null |
10.1038/nphys284
| null |
quant-ph cond-mat.soft physics.atom-ph
| null |
Electromagnetically induced transparency allows for light transmission
through dense atomic media by means of quantum interference. Media exhibiting
electromagnetically induced transparency have very interesting properties, such
as extremely slow group velocities. Associated with the slow light propagation
are quasiparticles, the so-called dark polaritons, which are mixtures of a
photonic and an atomic contribution. We here demonstrate that these excitations
behave as particles with a nonzero magnetic moment, which is in clear contrast
to the properties of a free photon. It is found that light passing through a
rubidium gas cell under the conditions of electromagnetically induced
transparency is deflected by a small magnetic field gradient. The deflection
angle is proportional to the optical propagation time through the cell. The
observed beam deflection can be understood by assuming that dark state
polaritons have an effective magnetic moment. Our experiment can be described
in terms of a Stern-Gerlach experiment for the polaritons.
|
[
{
"version": "v1",
"created": "Thu, 23 Mar 2006 19:05:47 GMT"
},
{
"version": "v2",
"created": "Mon, 19 Feb 2007 17:11:28 GMT"
}
] | 2015-06-26T00:00:00 |
[
[
"Karpa",
"Leon",
""
],
[
"Weitz",
"Martin",
""
]
] |
quant-ph/0603219
|
J.M. Geremia
|
JM Geremia
|
A Deterministic and Nondestructively-Verifiable Photon Number Source
| null | null |
10.1103/PhysRevLett.97.073601
| null |
quant-ph
| null |
We present a deterministic approach based on continuous measurement and
real-time quantum feedback control to prepare arbitrary photon number states of
a cavity mode. The procedure passively monitors the number state actually
achieved in each feedback stabilized measurement trajectory, thus providing a
nondestructively verifiable photon source. The feasibility of a possible cavity
QED implementation in the many-atom good-cavity coupling regime is analyzed.
|
[
{
"version": "v1",
"created": "Thu, 23 Mar 2006 19:35:47 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Geremia",
"JM",
""
]
] |
quant-ph/0603220
|
Xifeng Ren
|
Xi-Feng Ren, Guo-Ping Guo, Yun-Feng Huang, Chuan-Feng Li, Guang-Can
Guo
|
Plasmon assisted transmission of high dimensional orbital angular
momentum entangled state
|
7 pages,6 figures
|
Published in Europhysics Letters, Volume 76, 753, 2006
|
10.1209/epl/i2006-10359-2
| null |
quant-ph
| null |
We present an experimental evidence that high dimensional orbital angular
momentum entanglement of a pair of photons can be survived after a
photon-plasmon-photon conversion. The information of spatial modes can be
coherently transmitted by surface plasmons. This experiment primarily studies
the high dimensional entangled systems based on surface plasmon with
subwavelength structures. It maybe useful in the investigation of spatial mode
properties of surface plasmon assisted transmission through subwavelength hole
arrays.
|
[
{
"version": "v1",
"created": "Fri, 24 Mar 2006 01:12:44 GMT"
},
{
"version": "v2",
"created": "Thu, 7 Dec 2006 02:07:26 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Ren",
"Xi-Feng",
""
],
[
"Guo",
"Guo-Ping",
""
],
[
"Huang",
"Yun-Feng",
""
],
[
"Li",
"Chuan-Feng",
""
],
[
"Guo",
"Guang-Can",
""
]
] |
quant-ph/0603221
|
Darrick E. Chang
|
D.E. Chang, A.S. Sorensen, P.R. Hemmer, and M.D. Lukin
|
Strong coupling of single emitters to surface plasmons
|
34 pages, 7 figures
| null |
10.1103/PhysRevB.76.035420
| null |
quant-ph
| null |
We propose a method that enables strong, coherent coupling between individual
optical emitters and electromagnetic excitations in conducting nano-structures.
The excitations are optical plasmons that can be localized to sub-wavelength
dimensions. Under realistic conditions, the tight confinement causes optical
emission to be almost entirely directed into the propagating plasmon modes via
a mechanism analogous to cavity quantum electrodynamics. We first illustrate
this result for the case of a nanowire, before considering the optimized
geometry of a nanotip. We describe an application of this technique involving
efficient single-photon generation on demand, in which the plasmons are
efficiently out-coupled to a dielectric waveguide. Finally we analyze the
effects of increased scattering due to surface roughness on these
nano-structures.
|
[
{
"version": "v1",
"created": "Fri, 24 Mar 2006 01:33:31 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Chang",
"D. E.",
""
],
[
"Sorensen",
"A. S.",
""
],
[
"Hemmer",
"P. R.",
""
],
[
"Lukin",
"M. D.",
""
]
] |
quant-ph/0603222
|
Z. D. Wang
|
Li-Xiang Cen, Z. D. Wang, and S. J. Wang
|
Scalable solid-state quantum computation in decoherence-free subspaces
with trapped ions
|
4 pages, 1 figure
| null |
10.1103/PhysRevA.74.032321
| null |
quant-ph
| null |
We propose a decoherence-free subspaces (DFS) scheme to realize scalable
quantum computation with trapped ions. The spin-dependent Coulomb interaction
is exploited, and the universal set of unconventional geometric quantum gates
is achieved in encoded subspaces that are immune from decoherence by collective
dephasing. The scalability of the scheme for the ion array system is
demonstrated, either by an adiabatic way of switching on and off the
interactions, or by a fast gate scheme with comprehensive DFS encoding and
noise decoupling techniques.
|
[
{
"version": "v1",
"created": "Fri, 24 Mar 2006 12:45:45 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Cen",
"Li-Xiang",
""
],
[
"Wang",
"Z. D.",
""
],
[
"Wang",
"S. J.",
""
]
] |
quant-ph/0603223
|
Vahid Karimipour
|
V. Karimipour and L. Memarzadeh
|
Transition behavior in the capacity of correlated-noisy channels in
arbitrary dimensions
|
11 pages, Latex, 4 figures, Accepted for publication in Physical
Review A
|
Phys. Rev. A 74, 032332 (2006).
|
10.1103/PhysRevA.74.032332
| null |
quant-ph
| null |
We construct a class of quantum channels in arbitrary dimensions for which
entanglement improves the performance of the channel. The channels have
correlated noise and when the level of correlation passes a critical value we
see a sharp transition in the optimal input states (states which minimize the
output entropy) from separable to maximally entangled states. We show that for
a subclass of channels with some extra conditions, including the examples which
we consider, the states which minimize the output entropy are the ones which
maximize the mutual information.
|
[
{
"version": "v1",
"created": "Fri, 24 Mar 2006 14:54:50 GMT"
},
{
"version": "v2",
"created": "Thu, 20 Jul 2006 19:49:00 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Karimipour",
"V.",
""
],
[
"Memarzadeh",
"L.",
""
]
] |
quant-ph/0603224
|
Michael R. Geller
|
Michael R. Geller, Emily J. Pritchett, Andrew T. Sornborger, and F. K.
Wilhelm
|
Quantum computing with superconductors I: Architectures
|
NATO ASI book chapter, 24 pages
| null | null | null |
quant-ph
| null |
Josephson junctions have demonstrated enormous potential as qubits for
scalable quantum computing architectures. Here we discuss the current
approaches for making multi-qubit circuits and performing quantum information
processing with them.
|
[
{
"version": "v1",
"created": "Fri, 24 Mar 2006 15:04:16 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Geller",
"Michael R.",
""
],
[
"Pritchett",
"Emily J.",
""
],
[
"Sornborger",
"Andrew T.",
""
],
[
"Wilhelm",
"F. K.",
""
]
] |
quant-ph/0603225
|
Lucas Lamata
|
Lucas Lamata, Juan Leon, David Salgado
|
Spin entanglement loss by local correlation transfer to the momentum
|
7 pages and 7 figures. Accepted in PRA
|
Phys. Rev. A 73, 052325 (2006)
|
10.1103/PhysRevA.73.052325
| null |
quant-ph
| null |
We show the decrease of spin-spin entanglement between two s=1/2 fermions or
two photons due to local transfer of correlations from the spin to the momentum
degree of freedom of one of the two particles. We explicitly show how this
phenomenon operates in the case where one of the two fermions (photons) passes
through a local homogeneous magnetic field (optically-active medium), losing
its spin correlations with the other particle.
|
[
{
"version": "v1",
"created": "Fri, 24 Mar 2006 15:40:55 GMT"
},
{
"version": "v2",
"created": "Thu, 1 Jun 2006 08:28:37 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Lamata",
"Lucas",
""
],
[
"Leon",
"Juan",
""
],
[
"Salgado",
"David",
""
]
] |
quant-ph/0603226
|
Daniel E. Browne
|
Dan E. Browne and Hans J. Briegel
|
One-way Quantum Computation - a tutorial introduction
|
22 pages, a tutorial book chapter with a number of new methods and
observations. Minor errors corrected and a few additional references added
| null | null | null |
quant-ph
| null |
In this book chapter, we provide a tutorial introduction to one-way quantum
computation and many of the techniques one can use to understand it. The
techniques which are described include the stabilizer formalism and the logical
Heisenberg picture. We highlight ways in which it is useful to understand
one-way computation beyond simple equivalence with the quantum circuit model.
We briefly review current proposals of implementations and experimental
progress and summarize some recent related theoretical developments.
Although the chapter is primarily didactic in focus, we include a number of
new methods and observations. These include: a simpler and more compact
formulation of one-way quantum computation in the stabilizer formalism; A new
way of implementing unitaries diagonal in the computational basis; New results
on the family of operations which may be implemented in a single round of
measurements; A method for constructing compact one-way patterns by decomposing
unitaries in terms of diagonal unitaries and Clifford group transformations.
|
[
{
"version": "v1",
"created": "Fri, 24 Mar 2006 18:08:41 GMT"
},
{
"version": "v2",
"created": "Tue, 3 Oct 2006 15:27:56 GMT"
}
] | 2016-09-08T00:00:00 |
[
[
"Browne",
"Dan E.",
""
],
[
"Briegel",
"Hans J.",
""
]
] |
quant-ph/0603227
|
Dmitry Kamenev
|
D. I. Kamenev, G. P. Berman, and V. I. Tsifrinovich
|
Creation of entanglement in a scalable spin quantum computer with
long-range dipole-dipole interaction between qubits
|
31 pages
| null |
10.1103/PhysRevA.73.062336
| null |
quant-ph
| null |
Creation of entanglement is considered theoretically and numerically in an
ensemble of spin chains with dipole-dipole interaction between the spins. The
unwanted effect of the long-range dipole interaction is compensated by the
optimal choice of the parameters of radio-frequency pulses implementing the
protocol. The errors caused by (i) the influence of the environment,(ii)
non-selective excitations, (iii) influence of different spin chains on each
other, (iv) displacements of qubits from their perfect locations, and (v)
fluctuations of the external magnetic field are estimated analytically and
calculated numerically. For the perfectly entangled state the z component, M,
of the magnetization of the whole system is equal to zero. The errors lead to a
finite value of M. If the number of qubits in the system is large, M can be
detected experimentally. Using the fact that M depends differently on the
parameters of the system for each kind of error, varying these parameters would
allow one to experimentally determine the most significant source of errors and
to optimize correspondingly the quantum computer design in order to decrease
the errors and M. Using our approach one can benchmark the quantum computer,
decrease the errors, and prepare the quantum computer for implementation of
more complex quantum algorithms.
|
[
{
"version": "v1",
"created": "Fri, 24 Mar 2006 21:13:43 GMT"
}
] | 2009-11-13T00:00:00 |
[
[
"Kamenev",
"D. I.",
""
],
[
"Berman",
"G. P.",
""
],
[
"Tsifrinovich",
"V. I.",
""
]
] |
quant-ph/0603228
|
Jian-Ming Cai
|
Jian-Ming Cai, Zheng-Wei Zhou, Guang-Can Guo
|
Decoherence effects on the quantum spin channels
|
Revised version accepted in PRA
|
Phys. Rev. A. 74, 022328 (2006).
|
10.1103/PhysRevA.74.022328
| null |
quant-ph
| null |
An open ended spin chain can serves as a quantum data bus for the coherent
transfer of quantum state information. In this paper, we investigate the
efficiency of such quantum spin channels which work in a decoherence
environment. Our results show that, the decoherence will significantly reduce
the fidelity of quantum communication through the spin channels. Generally
speaking, as the distance increases, the decoherence effects become more
serious, which will put some constraints on the spin chains for long distance
quantum state transfer.
|
[
{
"version": "v1",
"created": "Sat, 25 Mar 2006 02:26:33 GMT"
},
{
"version": "v2",
"created": "Wed, 5 Apr 2006 14:21:13 GMT"
},
{
"version": "v3",
"created": "Sun, 11 Jun 2006 23:58:50 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Cai",
"Jian-Ming",
""
],
[
"Zhou",
"Zheng-Wei",
""
],
[
"Guo",
"Guang-Can",
""
]
] |
quant-ph/0603229
|
Per Kristian Rekdal
|
Per Kristian Rekdal, Bo-Sture K. Skagerstam, Ulrich Hohenester, Asier
Eiguren
|
Spin Decoherence in Superconducting Atom Chips
|
4 pages, 2 figures. Physical Review Letters (in press)
| null | null | null |
quant-ph cond-mat.soft
| null |
Using a consistent quantum-mechanical treatment for the electromagnetic
radiation, we theoretically investigate the magnetic spin-flip scatterings of a
neutral two-level atom trapped in the vicinity of a superconducting body. We
derive a simple scaling law for the corresponding spin-flip lifetime for such
an atom trapped near a superconducting thick slab. For temperatures below the
superconducting transition temperature T_c, the lifetime is found to be
enhanced by several orders of magnitude in comparison to the case of a normal
conducting slab. At zero temperature the spin-flip lifetime is given by the
unbounded free-space value.
|
[
{
"version": "v1",
"created": "Sat, 25 Mar 2006 18:44:55 GMT"
},
{
"version": "v2",
"created": "Fri, 7 Jul 2006 17:10:47 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Rekdal",
"Per Kristian",
""
],
[
"Skagerstam",
"Bo-Sture K.",
""
],
[
"Hohenester",
"Ulrich",
""
],
[
"Eiguren",
"Asier",
""
]
] |
quant-ph/0603230
|
Andis ChiTung Kwan
|
Xiangdong Li, Lin Leung, Andis Chi-Tung Kwan, Xiaowen Zhang, Dammika
Kahanda, Michael Anshel
|
Post-Quantum Key Exchange Protocols
|
11 pages, 2 figures. Submitted to SPIE DSS 2006; v2 citation typos
fixed; v3 appendix typos corrected
|
Proc. of SPIE Vol.6244, 62440N, (2006)
|
10.1117/12.665685
| null |
quant-ph
| null |
If an eavesdropper Eve is equipped with quantum computers, she can easily
break the public key exchange protocols used today. In this paper we will
discuss the post-quantum Diffie-Hellman key exchange and private key exchange
protocols.
|
[
{
"version": "v1",
"created": "Sat, 25 Mar 2006 20:44:42 GMT"
},
{
"version": "v2",
"created": "Sun, 4 Jun 2006 22:34:07 GMT"
},
{
"version": "v3",
"created": "Fri, 20 Oct 2006 14:12:01 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Li",
"Xiangdong",
""
],
[
"Leung",
"Lin",
""
],
[
"Kwan",
"Andis Chi-Tung",
""
],
[
"Zhang",
"Xiaowen",
""
],
[
"Kahanda",
"Dammika",
""
],
[
"Anshel",
"Michael",
""
]
] |
quant-ph/0603231
|
John Cooper w
|
John W. Cooper
|
Deutsch and Jozsa's Algorithm Revisited
|
7 pages
| null | null | null |
quant-ph
| null |
A classical analogue of Deutsch and Jozsa's algorithm is given and its
implications on quantum computing is discussed
|
[
{
"version": "v1",
"created": "Mon, 27 Mar 2006 18:21:22 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Cooper",
"John W.",
""
]
] |
quant-ph/0603232
|
Mariana Kirchbach
|
C. B. Compean, M. Kirchbach
|
The Quantum Mechanics Problem of the Schroedinger Equation with the
Trigonometric Rosen-Morse Potential
|
10 pages, 6 figures
| null | null | null |
quant-ph
| null |
We present the quantum mechanics problem of the one-dimensional Schroedinger
equation with the trigonometric Rosen-Morse potential. This potential is of
possible interest to quark physics in so far as it captures the essentials of
the QCD quark-gluon dynamics and (i) interpolates between a Coulomb-like
potential (associated with one-gluon exchange) and the infinite wall potential
(associated with asymptotic freedom), (ii) reproduces in the intermediary
region the linear confinement potential (associated with multi-gluon
self-interactions) as established by lattice QCD calculations of hadron
properties. Moreover, its exact real solutions given here display a new class
of real orthogonal polynomials and thereby interesting mathematical entities in
their own.
|
[
{
"version": "v1",
"created": "Sun, 26 Mar 2006 18:18:02 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Compean",
"C. B.",
""
],
[
"Kirchbach",
"M.",
""
]
] |
quant-ph/0603233
|
Yatendra Jain
|
Yatendra S. Jain
|
Wave Mechanics of Two Hard Core Quantum Particles in 1-D Box
|
12 pages, no figure
|
Central European J. Phys. 2(4) 2004, 709-719
|
10.2478/BF02475571
| null |
quant-ph
| null |
The wave mechanics of two impenetrable hard core particles in 1-D box is
analyzed. Each particle in the box behaves like an independent entity
represented by a {\it macro-orbital} (a kind of pair waveform). While the
expectation value of their interaction, $<V_{HC}(x)>$, vanishes for every state
of two particles, the expectation value of their relative separation, $<x>$,
satisfies $<x> \ge \lambda/2$ (or $q \ge \pi/d$, with $2d = L$ being the size
of the box). The particles in their ground state define a close-packed
arrangement of their wave packets (with $<x> = \lambda/2$, phase position
separation $\Delta\phi = 2\pi$ and momentum $|q_o| = \pi/d$) and experience a
mutual repulsive force ({\it zero point repulsion}) $f_o = h^2/2md^3$ which
also tries to expand the box. While the relative dynamics of two particles in
their excited states represents usual collisional motion, the same in their
ground state becomes collisionless. These results have great significance in
determining the correct microscopic understanding of widely different many body
systems.
|
[
{
"version": "v1",
"created": "Sun, 26 Mar 2006 08:43:28 GMT"
}
] | 2015-06-26T00:00:00 |
[
[
"Jain",
"Yatendra S.",
""
]
] |
quant-ph/0603234
|
Rainer Plaga
|
R.Plaga
|
A fundamental threat to quantum cryptography: gravitational attacks
|
Eur. Phys. J. D (2006), in print
|
Eur. Phys. J. D 38, 409-413 (2006)
|
10.1140/epjd/e2006-00045-y
| null |
quant-ph
| null |
An attack on the ``Bennett-Brassard 84''(BB84) quantum key-exchange protocol
in which Eve exploits the action of gravitation to infer information about the
quantum-mechanical state of the qubit exchanged between Alice and Bob, is
described. It is demonstrated that the known laws of physics do not allow to
describe the attack. Without making assumptions that are not based on broad
consensus, the laws of quantum gravity, unknown up to now, would be needed even
for an approximate treatment. Therefore, it is currently not possible to
predict with any confidence if information gained in this attack will allow to
break BB84. Contrary to previous belief, a proof of the perfect security of
BB84 cannot be based on the assumption that the known laws of physics are
strictly correct, yet.
|
[
{
"version": "v1",
"created": "Sun, 26 Mar 2006 09:05:30 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Plaga",
"R.",
""
]
] |
quant-ph/0603235
|
Eliahu Comay
|
E. Comay
|
The Yukawa Lagrangian Density is Inconsistent with the Hamiltonian
|
7 pages, 1 figure
| null | null |
2832-2006
|
quant-ph
| null |
It is proved that no Hamiltonian exists for the real Klein-Gordon field used
in the Yukawa interaction. The experimental side supports this conclusion.
|
[
{
"version": "v1",
"created": "Sun, 26 Mar 2006 10:58:12 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Comay",
"E.",
""
]
] |
quant-ph/0603236
|
Jian Wang
|
Jian Wang, Quan Zhang, Chao-jing Tang
|
Quantum secure communication protocols based on entanglement swapping
| null | null | null | null |
quant-ph
| null |
We present a quantum secure direct communication protocol and a multiparty
quantum secret sharing protocol based on Einstein-Podolsky-Rosen pairs and
entanglement swapping. The present quantum secure direct communication protocol
makes use of the ideal of block transmission. We also point out that the sender
can encode his or her secret message without ensuring the security of the
quantum channel firstly. In the multiparty quantum secret sharing protocol, the
communication parties adopt checking mode or encoding mode with a certain
probability. It is not necessary for the protocol to perform local unitary
operation. In both the protocols, one party transmits only one photon for each
Einstein-Podolsky-Rosen pair to another party and the security for the
transmitting photons is ensured by selecting Z-basis or X-basis randomly to
measure the sampling photons.
|
[
{
"version": "v1",
"created": "Sun, 26 Mar 2006 13:41:08 GMT"
}
] | 2007-05-23T00:00:00 |
[
[
"Wang",
"Jian",
""
],
[
"Zhang",
"Quan",
""
],
[
"Tang",
"Chao-jing",
""
]
] |
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