共查询到20条相似文献,搜索用时 31 毫秒
1.
Hai-Woong Lee 《量子光学学报》2006,12(B08):68-69
Single-particle entanglement refers to entanglement produced with a single particle. It can be generated by illuminating a beam splitter with a single photon. We describe experimental schemes to realize quantum teleportation and quantum key distribution utilizing single-particle entanglement, and discuss the strengths and drawbacks of the schemes compared with the standard scheme utilizing two-photon polarization states. We show, in particular, that the quantum key distribution scheme based on single-particle entanglement is associated with a relatively high value of the bits of information transferred per particle sent and can thus be cost effective. 相似文献
2.
In this paper, a two-party quantum private comparison (QPC) protocol is proposed by using five-qubit entangled states as the quantum resource. The proposed protocol needs the help from a semi-honest third party (TP), who is allowed to misbehave on his own but not allowed to conspire with the adversary including the dishonest user. The proposed protocol has the following distinct features: (1) One five-qubit entangled state can be used to achieve the equality comparison of two bits in each round of comparison; (2) Neither unitary operations nor quantum entanglement swapping technology is needed, both of which may consume expensive quantum devices; (3) Only Bell measurements and single-particle measurements are employed, both of which can be realized with current quantum technologies; (4) The security toward both the outside attack and the participant attack can be guaranteed; (5) The private information of two parties is not leaked out to TP. 相似文献
3.
Gilles Brassard 《Foundations of Physics》2003,33(11):1593-1616
Can quantum communication be more efficient than its classical counterpart? Holevo's theorem rules out the possibility of communicating more than n bits of classical information by the transmission of n quantum bits—unless the two parties are entangled, in which case twice as many classical bits can be communicated but no more. In apparent contradiction, there are distributed computational tasks for which quantum communication cannot be simulated efficiently by classical means. In some cases, the effect of transmitting quantum bits cannot be achieved classically short of transmitting an exponentially larger number of bits. In a similar vein, can entanglement be used to save on classical communication? It is well known that entanglement on its own is useless for the transmission of information. Yet, there are distributed tasks that cannot be accomplished at all in a classical world when communication is not allowed, but that become possible if the non-communicating parties share prior entanglement. This leads to the question of how expensive it is, in terms of classical communication, to provide an exact simulation of the spooky power of entanglement. 相似文献
4.
There are aspects of privacy theory that are analogous to quantum theory. In particular one can define distillable key and
key cost in parallel to distillable entanglement and entanglement cost. We present here classical privacy theory as a particular
case of information theory with adversaries, where similar general laws hold as in entanglement theory. We place the result
of Renner and Wolf—that intrinsic information is lower bound for key cost—into this general formalism. Then we show that the
question of whether intrinsic information is equal to key cost is equivalent to the question of whether Alice and Bob can
create a distribution product with Eve using IM bits of secret key. We also propose a natural analogue of relative entropy of entanglement in privacy theory and show that
it is equal to the intrinsic information. We also provide a formula analogous to the entanglement of formation for classical
distributions.
It is our pleasure to dedicate this paper to Asher Peres on the occasion of his seventieth birthday. 相似文献
5.
6.
F. Buscemi P. Bordone A. Bertoni 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2012,66(12):1-11
We estimate the role of noise in the formation of entanglement and in the appearance of single- and two-electron interference in systems of coupled one-dimensional channels. Two cases are considered: a single-particle interferometer and a two-particle interferometer exploiting Coulomb interaction. In both of them, environmental noise yields a randomization of the carrier phases. Our results assess how the complementarity relation linking single-particle behavior to nonlocal quantities (such as entanglement and environment-induced decoherence) acts in electron interferometry. We show that in an experimental implementation of the setups examined, one- and two-electron detection probability at the output drains can be used to evaluate the decoherence and the degree of entanglement. 相似文献
7.
8.
In this paper, a controlled quantum dialogue protocol is designed based on five-qubit entangled states. One five-qubit entangled state can be used to exchange one communicant’s two private bits with the other communicant’s two private bits under the control of an honest supervisor. Security analysis turns out that it can overcome the information leakage problem and can resist the active attacks from an outside attacker. The designed protocol only needs single-particle measurements and Bell state measurements, both of which can be realized with current technologies.
相似文献9.
Xin-Wen Wang Deng-Yu Zhang Shi-Qing Tang Li-Jun Xie 《International Journal of Theoretical Physics》2012,51(6):1978-1988
Entanglement swapping for four-qubit cluster-class states is studied. It is shown that a four-qubit cluster state (maximally
entangled) can be obtained with a certain probability from two four-qubit cluster-class states by entanglement swapping. The
probability is related to the smallest superposition coefficient of the cluster-class states (when all the moduli of amplitudes
are equivalent, they are the usual cluster states and the probability hits to one). Two examples for the applications of the
entanglement swapping are also presented. One is quantum teleportation of an arbitrary two-qubit state via a quantum repeater,
in which the success probability can be improved by the entanglement swapping when the quantum channels are general cluster-class states (partially entangled). The other is quantum key distribution, in which a secret random sequence of bits
(a “key”) can be efficiently established between two distant parties by the entanglement swapping of two groups of cluster
states. 相似文献
10.
We introduce a complete set of complementary quantities in bipartite, two-dimensional systems. Complementarity then relates the quantitative entanglement measure concurrence which is a bipartite property to the single-particle quantum properties predictability and visibility, for the most general quantum state of two qubits. Consequently, from an interferometric point of view, the usual wave-particle duality relation must be extended to a “triality” relation containing, in addition, the quantitative entanglement measure concurrence, which has no classical counterpart and manifests a genuine quantum aspect of bipartite systems. A generalized duality relation, that also governs possible violations of the Bell’s inequality, arises between single- and bipartite properties. 相似文献
11.
The existence of entangled quantum states gives extra power to quantum computers over their classical counterparts. Quantum entanglement shows up qualitatively at the level of two qubits. We demonstrate that the one- and the two-bit Deutsch-Jozsa algorithm does not require entanglement and can be mapped onto a classical optical scheme. It is only for three and more input bits that the DJ algorithm requires the implementation of entangling transformations and in these cases it is impossible to implement this algorithm classically. 相似文献
12.
The outcomes obtained in Bell tests involving two-outcome measurements on two subsystems can, in principle, generate up to 2?bits of randomness. However, the maximal violation of the Clauser-Horne-Shimony-Holt inequality guarantees the generation of only 1.23?bits of randomness. We prove here that quantum correlations with arbitrarily little nonlocality and states with arbitrarily little entanglement can be used to certify that close to the maximum of 2?bits of randomness are produced. Our results show that nonlocality, entanglement, and randomness are inequivalent quantities. They also imply that device-independent quantum key distribution with an optimal key generation rate is possible by using almost-local correlations and that device-independent randomness generation with an optimal rate is possible with almost-local correlations and with almost-unentangled states. 相似文献
13.
Ming-Xing Luo Lin Li Song-Ya Ma Xiu-Bo Chen Yi-Xian Yang 《International Journal of Theoretical Physics》2013,52(9):3032-3044
In this paper, we show that some special mixed quantum resource experience the same property of pure entanglement such as Bell state for quantum teleportation. It is shown that one mixed state and three bits of classical communication cost can be used to teleport one unknown qubit compared with two bits via pure resources. The schemes are easily implement with model physical techniques. Moreover, these resources are also optimal and typical for faithfully remotely prepare an arbitrary qubit, two-qubit and three-qubit states with mixed quantum resources. Our schemes are completed as same as those with pure quantum entanglement resources except only 1 bit additional classical communication cost required. The success probability is independent of the form of the mixed resources. 相似文献
14.
An experimental scheme is proposed for faithful teleportation of a unknown optical cat-state via attenuated quantum channel due to energy loss or photon absorption during the process of entanglement sharing. The scheme is probabilistic, yet conclusive, and the effective classical communication costs just Log23 bits, instead of five bits which are necessary for full record of the measurement outcome. The scheme uses only threshold (i.e., yes/no) detectors so that exact photon counting is not needed. However, it requires application of a nonlinear element called cross-phase modulator. Feasibility of the scheme is also discussed with respect to EIT-based modern techniques. 相似文献
15.
Using an operational definition we quantify the entanglement, E(P), between two parties who share an arbitrary pure state of N indistinguishable particles. We show that E(P)< or =E(M), where E(M) is the bipartite entanglement calculated from the mode-occupation representation. Unlike E(M), E(P) is superadditive. For example, E(P)=0 for any single-particle state, but the state |1>|1>, where both modes are split between the two parties, has E(P)=1/2. We discuss how this relates to quantum correlations between particles, for both fermions and bosons. 相似文献
16.
In this paper, we investigate perfect quantum teleportation and dense coding by using an 2N-qubit W state channel. In the quantum teleportation scheme, an unknown N-qubit entangled state can be perfectly teleported. One ebit of entanglement and two bits of classical communication are consumed in the teleportation process, just like when using the Bell state channel. While N+1 bits of classical information can be transmitted by only sending N particles in the dense coding protocol. 相似文献
17.
D. C. Li Z. L. Cao 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,50(2):207-214
We investigate the entanglement in a two-qubit Heisenberg XYZ
system with different Dzyaloshinskii-Moriya (DM) interaction and
inhomogeneous magnetic field. It is found that the control
parameters (Dx, Bx and bx) are remarkably different
with the common control parameters (Dz, Bz and bz)
in the entanglement and the critical temperature, and these
x-component parameters can increase the entanglement and the
critical temperature more efficiently. Furthermore, we show the
properties of these x-component parameters for the control of
entanglement. In the ground state, increasing Dx (spin-orbit
coupling parameter) can decrease the critical value bxc and
increase the entanglement in the revival region, and adjusting
some parameters (increasing bx and J, decreasing Bx
and Δ) can decrease the critical value Dxc to enlarge
the revival region. In the thermal state, increasing Dx can
increase the revival region and the entanglement in the revival
region (for T or bx), and enhance the critical value
Bxc to make the region of high entanglement larger. Also, the
entanglement and the revival region will increase with the
decrease of Bx (uniform magnetic field). In addition, small
bx (nonuniform magnetic field) has some similar properties to
Dx, and with the increase of bx the entanglement also
has a revival phenomenon, so that the entanglement can exist at
higher temperature for larger bx. 相似文献
18.
We examine quantum entanglement as a physical phenomenon independent of specific problems of quantum information technologies. Within the dynamic symmetry approach, we briefly discuss the role of quantum fluctuations in formation of entangled states, including single-particle entanglement, relativity of entanglement with respect to the choice of basic observables, and stabilization of robust entanglement. 相似文献
19.
All previous tests of local realism have studied correlations between single-particle measurements. In the present experiment, we have performed a Bell experiment on three particles in which one of the measurements corresponds to a projection onto a maximally entangled state. We show theoretically and experimentally that correlations between these entangled measurements and single-particle measurements are too strong for any local-realistic theory and are experimentally exploited to violate a Clauser-Horne-Shimony-Holt-Bell inequality by more than 5 standard deviations. We refer to this possibility as "entangled entanglement." 相似文献
20.
We analyze a Hanbury Brown-Twiss geometry in which particles are injected from two independent sources into a mesoscopic conductor in the quantum Hall regime. All partial waves end in different reservoirs without generating any single-particle interference; in particular, there is no single-particle Aharonov-Bohm effect. However, exchange effects lead to two-particle Aharonov-Bohm oscillations in the zero-frequency current cross correlations. We demonstrate that this is related to two-particle orbital entanglement, detected via violation of a Bell inequality. The transport is along edge states and only adiabatic quantum point contacts and normal reservoirs are employed. 相似文献