共查询到20条相似文献,搜索用时 15 毫秒
1.
P. Navez 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(2):219-228
We describe a cryptographic protocol consisting of two entangled beams of squeezed light which makes use of statistical tests
to deduce the secret key bit. The sender (Alice) encrypts a secret key by modulating the phase of the beam sent in public
by the receiver (Bob) who keeps the other beam private. The knowledge of the degree of non classical correlation between the
beam quadrature components measured in private and in public allows only Bob to decrypt the secret key. With a view towards
absolute security, we formally prove that any external intervention from an eavesdropper (Eve) during the communication process
introduces necessarily some modification susceptible to be detected. Statistical confidentiality tests are proposed to detect
the presence of Eve.
Received 12 July 2001 and Received in final form 11 November 2001 相似文献
2.
A. Khalique G. M. Nikolopoulos G. Alber 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,40(3):453-464
The influence of imperfections on
achievable secret-key generation rates of quantum key distribution protocols
is investigated. As examples of relevant imperfections, we consider
tagging of Alice's qubits and dark counts at Bob's detectors, while
we focus on a powerful eavesdropping strategy which takes full advantage of
tagged signals.
It is demonstrated that error correction and privacy amplification based on
a combination of a two-way classical communication protocol and
asymmetric Calderbank-Shor-Steane codes may significantly postpone the
disastrous influence of dark counts. As a result, the
distances are increased considerably
over which a secret key can be distributed in optical fibres reliably.
Results are presented for the four-state, the six-state, and
the decoy-state protocols. 相似文献
3.
Y. Cao A.-M. Wang X.-S. Ma N.-B. Zhao 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(3):607-617
Based on controlled order rearrange encryption (CORE) for
quantum key distribution using EPR pairs [Fu.G. Deng, G.L. Long,
Phys. Rev. A 68, 042315 (2003)], we propose generalized controlled order
rearrangement encryption (GCORE) protocols of N qubits and N
qutrits, and concretely display them in cases using 3-qubit,
2-qutrit maximally entangled basis states. We further show that our
protocols will become safer with an increase in dimensions and
number of particles. Moreover, we carry out the security analysis
using quantum covariant cloning machine. Although the applications
of the generalized scheme need to be further studied, GCORE has many
distinct features such as large capacity and high efficiency. 相似文献
4.
M. Genovese C. Novero 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,21(1):109-113
We propose a quantum transmission based on bi-photons, which are doubly-entangled both in polarisation and phase. This scheme
finds a natural application in quantum cryptography, where we show that an eventual eavesdropper is bound to introduce a larger
error on the quantum communication than for a single entangled bi-photon communication, when he steels the same information.
Received 23 July 2001 / Received in final form 30 November 2001 Published online 24 September 2002 相似文献
5.
G. Benenti S. Felloni G. Strini 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(2):389-396
We study the stability under quantum noise effects of the quantum privacy amplification protocol for the purification of entanglement
in quantum cryptography. We assume that the E91 protocol is used by two communicating parties (Alice and Bob) and that the
eavesdropper Eve uses the isotropic Bužek-Hillery quantum copying machine to extract information.
Entanglement purification is then operated by Alice and Bob by means of the quantum privacy amplification protocol and we
present a systematic numerical study of the impact of all possible
single-qubit noise channels on this protocol. We find that both the qualitative behavior of the fidelity of the purified state
as a function of the number of purification steps and
the maximum level of noise that can be tolerated by the protocol strongly depend on the specific noise channel. These results
provide valuable information for experimental implementations of the quantum privacy amplification protocol. 相似文献
6.
Y. B. Sheng F. G. Deng 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,48(2):279-284
We present an efficient and economic scheme for five-party quantum
state sharing of an arbitrary m-qubit state with 2m three-particle
Greenberger-Horne-Zeilinger (GHZ) states and three-particle
GHZ-state measurements. It is more convenient than other schemes as
it only resorts to three-particle GHZ states and three-particle
joint measurement, not five-particle entanglements and five-particle
joint measurements. Moreover, this symmetric scheme is in principle
secure even though the number of the dishonest agents is more than
one. Its total efficiency approaches the maximal value. 相似文献
7.
W.L. Barnes G. Björk J.M. Gérard P. Jonsson J.A.E. Wasey P.T. Worthing V. Zwiller 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(2):197-210
We examine the problem of efficiently collecting the photons produced by solid-state single photon sources. The extent of
the problem is first established with the aid of simple physical concepts. Several approaches to improving the collection
efficiency are then examined and are broadly categorized into two types. First are those based on cavity quantum dynamics,
in which the pathways by which the source may emit a photon are restricted, thus channeling emission into one desired mode.
Second are those where we try to reshape the free space modes into a target mode in an optimal way, by means of refraction,
without fundamentally altering the way in which the source emits. Respectively, we examine a variety of microcavities and
solid immersion lenses. Whilst we find that the micropillar microcavities offer the highest collection efficiency (∼70%),
choosing this approach may not always be appropriate due to other constraints. Details of the different approaches, their
merits and drawbacks are discussed in detail.
Received 19 July 2001 and Received in final form 5 October 2001 相似文献
8.
Given the Mayers–Lo–Chau (MLC) no-go theorem, unconditionally secure quantum bit commitment (QBC) is impossible and hence quantum oblivious transfer (QOT) based on QBC is insecure. In this paper, we propose a secure all-or-nothing QOT protocol and a one-out-of-two QOT protocol respectively. The unique merit of the proposed protocols lies in that it is not based on QBC but based on an untrusted third party. Moreover, the proposed protocols do not violate Lo's no-go theorem so that their security can be achieved. 相似文献
9.
J.-M. Merolla L. Duraffourg J.-P. Goedgebuer A. Soujaeff F. Patois W.T. Rhodes 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(2):141-146
We report a new quantum cryptographic system involving single sideband detection and allowing an implementation of the BB84
protocol. The transmitted bits are reliably coded by the phase of a high frequency modulating signal. The principle of operation
is described in terms of both classical and quantum optics. The method has been demonstrated experimentally at 1 550 nm using
compact and conventional device technology. Single photon interference has been obtained with a fringe visibility greater
than 98%, indicating that the system can be used in view of quantum key distribution potentially beyond 50-km-long standard
single-mode fiber.
Received 13 July 2001 and Received in final form 30 November 2001 相似文献
10.
I. M. Herbauts S. Bettelli H. Hübel M. Peev 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(2):395-406
Some MIT researchers [Phys. Rev. A
75, 042327 (2007)] have recently claimed that
their implementation of the Slutsky-Brandt attack [Phys. Rev. A
57, 2383 (1998); Phys. Rev. A 71, 042312 (2005)] to
the BB84 quantum-key-distribution (QKD) protocol puts the security of this
protocol “to the test” by simulating “the most powerful
individual-photon attack” [Phys. Rev. A 73, 012315
(2006)].
A related unfortunate news feature by a
scientific journal [G. Brumfiel, Quantum cryptography is hacked, News @ Nature (april 2007); Nature 447, 372 (2007)]
has spurred some concern in the QKD community and among the general public
by misinterpreting the implications of this work. The present article
proves the existence of a stronger individual attack on QKD protocols with
encrypted error correction, for which tight bounds are shown, and clarifies
why the claims of the news feature incorrectly suggest a contradiction with
the established “old-style” theory of BB84 individual attacks.
The full implementation of a quantum cryptographic protocol includes a
reconciliation and a privacy-amplification stage, whose choice alters in
general both the maximum extractable secret and the optimal eavesdropping
attack. The authors of [Phys. Rev. A
75, 042327 (2007)] are concerned only with the error-free
part of the so-called sifted string, and do not consider faulty bits,
which, in the version of their protocol, are discarded. When using the
provably superior reconciliation approach of encrypted error correction
(instead of error discard), the Slutsky-Brandt attack is no more optimal
and does not “threaten” the security bound derived by Lütkenhaus [Phys. Rev. A 59, 3301 (1999)].
It is shown that the method of Slutsky and collaborators [Phys. Rev. A
57, 2383 (1998)] can
be adapted to reconciliation with error correction, and that the optimal
entangling probe can be explicitly found. Moreover, this attack fills
Lütkenhaus bound, proving that it is tight (a fact which was not
previously known). 相似文献
11.
J. Bouda M. Koniorczyk A. Varga 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,53(3):365-372
Channels encrypting quantum bits by the application of randomly
chosen unitary operators are studied. Quantities based on averages of
linear entropies which characterize certain aspects
of the encoding quality and the non-malleability of the
channels are introduced. The relation between the entropy of the classical key and
the choice of the encryption operators with the behaviour of these
properties is discussed. The extension of exact private quantum
channels in order to improve non-malleability via additional
encryption operators is considered. 相似文献
12.
J. Dong J. F. Teng 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,49(1):129-134
In this paper, we explicitly present a general scheme for controlled quantum teleportation of an arbitrary multi-qudit state
with unit fidelity and non-unit successful probability using d-dimensional nonmaximally entangled GHZ states as the quantum channel and generalized d-dimensional Bell states as the measurement basis. The expression of successful probability for controlled teleportation is
present depending on the degree of entanglement matching between the quantum channel and the generalized Bell states. And
the formulae for the selection of operations performed by the receiver are given according to the results measured by the
sender and the controller.
相似文献
13.
P.J. Edwards G.H. Pollard W.N. Cheung 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(2):147-153
Quantum key exchanges using weak coherent (Poissonian) single-photon sources are open to attack by a variety of eavesdropping
techniques. Quantum-correlated photon sources provide a means of flagging potentially insecure multiple-photon emissions and
thus extending the secure quantum key channel capacity and the secure key distribution range. We present indicative photon-counting
statistics for a fully correlated Poissonian multibeam photon source in which the transmitted beam is conditioned by photon
number measurements on the remaining beams with non-ideal multiphoton counters. We show that significant rejection of insecure
photon pulses from a twin-beam source cannot be obtained with a detector having a realistic quantum efficiency. However quantum-correlated
(quadruplet or octuplet) multiplet photon sources conditioned by high efficiency multiphoton counters could provide large
improvements in the secure channel capacity and the secure distribution range of high loss systems such as those using the
low earth orbit satellite links proposed for global quantum key distribution.
Received 14 July and Received in final form 20 November 2001 相似文献
14.
Pil H. Song ILki Kim 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(2):299-303
We study the effects of dissipation or leakage on the time evolution of Grover's algorithm for a quantum computer. We introduce
an effective two-level model with dissipation and randomness (imperfections), which is based upon the idea that ideal Grover's
algorithm operates in a 2-dimensional Hilbert space. The simulation results of this model and Grover's algorithm with imperfections
are compared, and it is found that they are in good agreement for appropriately tuned parameters. It turns out that the main
features of Grover's algorithm with imperfections can be understood in terms of two basic mechanisms, namely, a diffusion
of probability density into the full Hilbert space and a stochastic rotation within the original 2-dimensional Hilbert space.
Received 12 August 2002 / Received in final form 14 October 2002 Published online 4 February 2003 相似文献
15.
Quantum state sharing of an arbitrary two-qubit state
with two-photon entanglements and Bell-state measurements 总被引:4,自引:0,他引:4
F.-G. Deng X.-H. Li C.-Y. Li P. Zhou H.-Y. Zhou 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,39(3):459-464
Two schemes for sharing an arbitrary two-qubit state based on
entanglement swapping are proposed with Bell-state measurements
and local unitary operations. One is based on the quantum channel
with four Einstein-Podolsky-Rosen (EPR) pairs shared in advance.
The other is based on a circular topological structure, i.e., each
user shares an EPR pair with his neighboring one. The advantage of
the former is that the construction of the quantum channel between
the agents is controlled by the sender Alice, which will improve
the security of the scheme. The circular scheme reduces the
quantum resource largely when the number of the agents is large.
Both of those schemes have the property of high efficiency as
almost all the instances can be used to split the quantum
information. They are more convenient in application than the
other schemes existing as they require only two-qubit
entanglements and two-qubit joint measurements for sharing an
arbitrary two-qubit state. 相似文献
16.
Quantum state sharing of an arbitrary
multiqubit state using nonmaximally entangled GHZ states 总被引:1,自引:0,他引:1
Z.-X. Man Y.-J. Xia N. B. An 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,42(2):333-340
We explicitly present a scheme for quantum
state sharing of an arbitrary multiqubit state using nonmaximally
entangled GHZ states as the quantum channel and generalized Bell
states as the measurement basis. The scheme succeeds only
probabilistically with its total success probability depending on
the degree of entanglement matching between the quantum channel and
the generalized Bell states. Security of the scheme is guaranteed by
the fact that attacks of an outside eavesdropper or/and an inside
dishonest party will inevitably introduce detectable errors. 相似文献
17.
U. Yurtsever D. Strekalov J.P. Dowling 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(3):365-371
A quantum gravity-gradiometer consists of two spatially separated ensembles of atoms interrogated by pulses of a common laser
beam. The laser pulses cause the probability amplitudes of atomic ground-state hyperfine levels to interfere, producing two,
motion-sensitive, phase shifts, which allow the measurement of the average acceleration of each ensemble, and, via simple
differencing, of the acceleration gradient. Here we propose entangling the quantum states of atoms from the two ensembles
prior to the pulse sequence, and show that entanglement encodes their relative acceleration in a single interference phase
which can be measured directly, with no need for differencing.
Received 6 June 2002 / Received in final form 25 October 2002 Published online 28 January 2003 相似文献
18.
I.O. Kulik T. Hakioğlu A. Barone 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,30(2):219-226
We examine a generic three level mechanism of quantum computation in which all fundamental single and double qubit quantum
logic gates are operating under the effect of adiabatically controllable static (radiation free) bias couplings between the
states. Under the time evolution imposed by these bias couplings the quantum state cycles between the two degenerate levels
in the ground state and the quantum gates are realized by changing Hamiltonian at certain time intervals when the system collapses
to a two state subspace. We propose a physical implementation of the mechanism using Aharonov-Bohm persistent-current loops
in crossed electric and magnetic fields, with the output of the loop read out by using a quantum Hall effect aided mechanism.
Received 26 March 2002 / Received in final form 8 July 2002
Published online 19 November 2002 相似文献
19.
G. Benenti G. Casati S. Montangero D.L. Shepelyansky 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(2):293-296
We study the properties of eigenstates of an operating quantum computer which simulates the dynamical evolution in the regime
of quantum chaos. Even if the quantum algorithm is polynomial in number of qubits nq, it is shown that the ideal eigenstates become mixed and strongly modified by static imperfections above a certain threshold
which drops exponentially with nq. Above this threshold the quantum eigenstate entropy grows linearly with nq but the computation remains reliable during a time scale which is polynomial in the imperfection strength and in nq.
Received 7 March 2002/ Received in final form 3 May 2002 Published online 19 July 2002 相似文献
20.
G. Benenti G. Casati S. Montangero D.L. Shepelyansky 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(2):285-293
We investigate the transition to quantum chaos, induced by static imperfections, for an operating quantum computer that simulates
efficiently a dynamical quantum system, the sawtooth map. For the different dynamical regimes of the map, we discuss the quantum
chaos border induced by static imperfections by analyzing the statistical properties of the quantum computer eigenvalues.
For small imperfection strengths the level spacing statistics is close to the case of quasi-integrable systems while above
the border it is described by the random matrix theory. We have found that the border drops exponentially with the number
of qubits, both in the ergodic and quasi-integrable dynamical regimes of the map characterized by a complex phase space structure.
On the contrary, the regime with integrable map dynamics remains more stable against static imperfections since in this case
the border drops only algebraically with the number of qubits.
Received 19 June 2002 / Received in final form 30 September 2002 Published online 17 Decembre 2002
RID="a"
ID="a"e-mail: dima@irsamc.ups-tlse.fr
RID="b"
ID="b"UMR 5626 du CNRS 相似文献