Interference due to coherence swapping

We propose a method called ‘coherence swapping’ which enables us to create superposition of a particle in two distinct paths, which is fed with initially incoherent, independent radiation. This phenomenon is also present for the charged particles, and can be used to swap the effect of flux line due to the Aharonov-Bohm effect. We propose an optical version of experimental set-up to test the coherence swapping. The phenomenon, which is simpler than entanglement swapping or teleportation, raises some fundamental questions about the true nature of wave-particle duality, and also opens up the possibility of studying the quantum erasure from a new angle.     

Interference from nonlocal double-slit with pseudo-thermal light

We perform an interference experiment in which a pseudo-thermal light beam illuminates two spatially separated apertures, whose superposition at the same place forms a double-slit. The experimental result exhibits a typical double-slit interference fringe in the intensity correlation measurement, in agreement with the theoretical analysis by means of the property of the second-order spatial correlation of field of the thermal light.     

Remote interactions between two d-dimensional distributed quantum systems： nonlocal generalized quantum control-NOT gate and entanglement swapping

We present a systematic simple method to implement a generalized quantum control-NOT （CNOT） gate on two d-dimensional distributed systems. First, we show how the nonlocal generalized quantum CNOT gate can be implemented with unity fidelity and unity probability by using a maximally entangled pair of qudits as a quantum channel. We also put forward a scheme for probabilistically implementing the nonlocal operation with unity fidelity by employing a partially entangled qudit pair as a quantum channel. Analysis of the scheme indicates that the use of partially entangled quantum channel for implementing the nonlocal generalized quantum CNOT gate leads to the problem of ＇the general optimal information extraction＇. We also point out that the nonlocal generalized quantum CNOT gate can be used in the entanglement swapping between particles belonging to distant users in a communication network and distributed quantum computer.[第一段]     

The Schrödinger equation for quantum fields with nonlinear nonlocal scattering

This paper considers perturbationsH=H ₀+V of the Hamiltonian operatorH ₀ of a free scalar Boson field.V is a polynomial in the annihilation creation operators. Terms of any order are allowed inV, but point interactions, such as :0(x)⁴(x)⁴:dx, are not considered. Unnormalized solutions for the Schrödinger equation are found. For 0, these solutions have a partial asymptotic expansion in powers of . The set of all possible pertubation termsV forms a Lie algebra. General properties of this Lie algebra are investigated.This work was supported in part by the National Science Foundation, NSF GP-4364.     

Interference and switching of Josephson current carried by nonlocal spin-entangled electrons in a SQUID-like system with quantum dots

The Josephson current of spin-entangled electrons through the two branches of a SQUID-like structure with two quantum dots exhibits a magnetic-flux response different from the conventional Josephson current. Because of their interference, the period of maximum Josephson current changes from h/2e to h/e, which can be used for detecting the Cooper-pair splitting efficiency. The nonlocal spin entanglement provides a quantum mechanical functionale for switching on and off this novel Josephson current, and explicitly a switch is formulated by including a pilot junction. It is shown that the device can be used to measure the magnitude of split-tunneling Josephson current.     

Relativity of quantum states in entanglement swapping

The entanglement swapping protocol is analyzed in a relativistic setting, where shortly after the entanglement swapping is performed, a Bell test is performed. For an observer in the laboratory frame, a Bell violation is observed between the qubits with the swapped entanglement. In a moving frame, the order of the measurements is reversed, and a Bell violation is observed even though the particles are not entangled, directly or indirectly, or at any point in time. Although the measurement results are identical, the wavefunctions for the two frames are starkly different — one is entangled and the other is not. Furthermore, for boosts in a perpendicular direction, in the presence of decoherence, we show that the maximum Bell violation can occur across non-simultaneous points in time. This is a signature of entanglement that is spread across both space and time, showing both non-local and non-simultaneous aspects of entanglement.     

Catalysis in nonlocal quantum operations

We show how entanglement can be used, without being consumed, to accomplish unitary operations that could not be performed without it. When applied to infinitesimal transformations, our method makes equivalent, in the sense of Hamiltonian simulation, a whole class of otherwise inequivalent two-qubit interactions. The new catalysis effect also implies the asymptotic equivalence of all such interactions.     

Proof of a quantum mechanical nonlocal influence

First it is proved that, in a deterministic theory, Malus' law requires that, if a photon is successively transmitted by two polarizers with appropriately chosen settings, the first transmission influences a hidden variable (co-) determining the second one. We derive from this that in an ideal EPR experiment (giving the result predicted by quantum mechanics for two correlated photons transmitted by two polarizers with suitably chosen settings) there has to be a nonlocal influence from the first transmission interaction to the second. Subsequently we argue that we can abandon determinism as an assumption so that the locality hypothesis is in any case untenable if the predictions of quantum mechanics are all correct.     

Collapse-induced quantum nonlocal effect

In this article we attempt to bring out some significant general aspects of what we call collapse-induced quantum nonlocal effects resulting from the use of the hypothesis of wave function collapse.     

Nonlinear scattering with nonlocal interaction

We consider the scattering problem for the Hartree type equation in ⁿ withn2:

Activation of nonlocal quantum resources

We find two two-qubit bipartite states ρ1, ρ2 such that arbitrarily many copies of one or the other cannot exhibit nonlocal correlations in a two-setting-two-outcome Bell scenario. However, the bipartite state ρ1 ? ρ2 violates the Clauser-Horne-Shimony-Holt (CHSH) Bell inequality [J. F. Clauser, M. A. Horne, A. Shimony, and R. A. Holt, Phys. Rev. Lett. 23, 880 (1969).] by an amount of 2.023. We also identify a CHSH-local state ρ such that ρ?2 is CHSH inequality-violating. The tools employed can be easily adapted to find instances of nonlocality activation in arbitrary Bell scenarios.     

Polarized deuteron elastic scattering from a polarized proton target

Measurements are reported of the spin correlation parameter C_y,y for the elastic scattering of 10.0 MeV vector polarized deuterons from a polarized proton target at five CM angles (76°, 85°, 98°, 115°, 132°). The experimental results are compared with different predictions. A Faddeev type calculation on the basis of local potentials also including approximate Coulomb distortion is favoured by our experimental results.     

Deep inelastic scattering from quantum fluids

A simple and general argument is given for the deep inelastic behavior of the dynamic structure function of quantum fluids at zero temperature. The resulting high-energy tail is shown to give a reasonable fit to existing neutron data for liquid ⁴He.     

Interference in light scattering from slightly rough dielectric layers

The scattering of light from a slightly rough surface overlying a reflecting surface is investigated. It is shown that the long-scale component of the roughness spectrum plays a critical role in the scattering patterns obtained. The scattered interference patterns are critically dependent on small variation of the rms height of the long-scale component of the roughness. Conventional perturbation theory is found to be invalid in cases in which interference phenomena in the scattering are of importance. A model is proposed that quantitatively describes the measured angular intensity distributions.     

QCD effects in semi-inclusive deep inelastic scattering from a polarized target

The next-to-leading logarithmic corrections to cross-sections for semi-inclusive deep inelastic scattering from a polarized target are worked out. Predictions for pion asymmetries and pion charge ratios are given.     

基于纠缠交换的仲裁量子签名方案

提出了一种基于量子纠缠交换的仲裁签名协议. 以Bell态为基础,首先将待签消息利用幺正算符序列进行编码,通过算符序列对Bell态进行调制,再通过对量子信息加密产生签名.验证者将签名信息与仲裁者通过纠缠交换所产生的关联态相结合,通过Bell测量来对签名的真实性进行验证.算法利用量子加密保障了真实签名的不可伪造性,同时通过仲裁的参与结合量子密钥有效解决了双方的抵赖问题,方案还能够有效实现对通信双方隐私信息的保护. 关键词： 量子密码 量子签名 纠缠交换     

Secret sharing of quantum information via entanglement swapping

Based on entanglement swapping, a scheme for the secret sharing of an arbitrary two-particle entangled state is proposed. If the controllers do not co-operate with the eavesdropper, the eavesdropper's successful probability decreases with the number of the controllers increasing. In addition, only the Bell-state measurements are required to realize the secret sharing scheme.     

Controlled mutual quantum entity authentication using entanglement swapping

In this paper, we suggest a controlled mutual quantum entity authentication protocol by which two users mutually certify each other on a quantum network using a sequence of Greenberger–Horne–Zeilinger(GHZ)-like states. Unlike existing unidirectional quantum entity authentication, our protocol enables mutual quantum entity authentication utilizing entanglement swapping; moreover, it allows the managing trusted center(TC) or trusted third party(TTP) to effectively control the certification of two users using the nature of the GHZ-like state. We will also analyze the security of the protocol and quantum channel.