Violations of Locality Beyond Bell's Theorem

Locality and realism are two main assumptions in deriving Bell's inequalities. Though the experimentally demonstrated violations of Bell's inequalities rule out local realism, it is, however, not clear what role each of the two assumptions solely plays in the observed violations. Here we show that two testable inequalities for the statistical predictions of two-qubit systems can be derived by assuming either locality or realism. It turns out that quantum mechanics respects a nonlocal classical realism, and it is locality that is incompatible with experimental observations and quantum mechanics.Comment: 4 pages, 1 figure; comments are welcom

Numerical solution to the Bloch equations, paramagnetic solutions under wideband continuous radio frequency irradiation in a pulsed magnetic field

A novel NMR experimental scheme, called wide band continuous wave NMR, is presented in this article

Linear Optics Quantum Communication over Long Distances

We propose a feasible scheme for teleporting an arbitrary polarization state or entanglement of photons by requiring only single-photon (SP) sources, simple linear optical elements and SP quantum non-demolition measurements. An unknown SP polarization state can be faithfully teleported either to a duplicate polarization state or to an entangled state. Our proposal can be used to implement long-distance quantum communication in a simple way. The scheme is within the reach of current technology and significantly simplifies the realistc implementation of long-distance high-fidelity quantum communication with photon qubits.Comment: 4 pages, no figure; comments are welcome / with refs. added and other change

Feasible Linear-optics Generation of Polarization-entangled Photons Assisted with Single-photon Quantum Non-demolition Measurement

We propose a feasible scheme to create $n$-party ($n\geq 2$) polarization-entangled photon states in a controllable way. The scheme requires only single-photon sources, single-photon quantum non-demolition measurement (SP-QNDM) and simple linear optical elements, usually with high perfections. The SP-QNDM acts as a non-destructive projection measurement onto the wanted entangled states and filters out the unwanted terms. Our scheme in fact realizes entanglement of non-interacting photons; the interaction occurs only implicitly in the optical elements and SP-QNDM. We also briefly consider purification of mixed single-photon states within our scheme.Comment: 4 pages, no figur

Holographic thermalization and gravitational collapse in the spacetime dominated by quintessence dark energy

In this paper, the thermalization has been studied holographically. Explicitly in the gravity side, we consider the gravitational collapse of a thin shell of dust in a spacetime dominated by quintessence dark energy. With the thermalization probes such as the normalized geodesic length and minimal area surface, we study the effect of the state parameter for the quintessence dark energy on the thermalization. Our results show that the smaller the state parameter of quintessence is, the harder the plasma to thermalize. We also investigate the thermalization velocity and thermalization acceleration. We hope our results here can shed light on the nature of the quintessence dark energy.Comment: minor modifications. arXiv admin note: text overlap with arXiv:1407.526

Exact solution to an extremal problem on graphic sequences with a realization containing every 22-tree on kk vertices

A simple graph $G$ is an {\it 2-tree} if $G=K_3$, or $G$ has a vertex $v$ of degree 2, whose neighbors are adjacent, and $G-v$ is an 2-tree. Clearly, if $G$ is an 2-tree on $n$ vertices, then $|E(G)|=2n-3$. A non-increasing sequence $\pi=(d_1,\ldots,d_n)$ of nonnegative integers is a {\it graphic sequence} if it is realizable by a simple graph $G$ on $n$ vertices. Yin and Li (Acta Mathematica Sinica, English Series, 25(2009)795--802) proved that if $k\ge 2$, $n\ge \frac{9}{2}k^2+\frac{19}{2}k$ and $\pi=(d_1,\ldots,d_n)$ is a graphic sequence with $\sum\limits_{i=1}^n d_i>(k-2)n$, then $\pi$ has a realization containing every 1-tree (the usual tree) on $k$ vertices. Moreover, the lower bound $(k-2)n$ is the best possible. This is a variation of a conjecture due to Erd\H{o}s and S\'{o}s. In this paper, we investigate an analogue problem for $2$-trees and prove that if $k\ge 3$ is an integer with k\equiv i(\mbox{mod }3), $n\geq20\lfloor\frac{k}{3}\rfloor^2+31\lfloor\frac{k}{3}\rfloor+12$ and $\pi=(d_1,\ldots,d_n)$ is a graphic sequence with $\sum\limits_{i=1}^n d_i>\max\{(k-1)(n-1),2\lfloor\frac{2k}{3}\rfloor n-2n-\lfloor\frac{2k}{3}\rfloor^2+\lfloor\frac{2k}{3}\rfloor+1-(-1)^i\}$, then $\pi$ has a realization containing every 2-tree on $k$ vertices. Moreover, the lower bound $\max\{(k-1)(n-1),2\lfloor\frac{2k}{3}\rfloor n-2n-\lfloor\frac{2k}{3}\rfloor^2+\lfloor\frac{2k}{3}\rfloor+1-(-1)^i\}$ is the best possible. This result implies a conjecture due to Zeng and Yin (Discrete Math. Theor. Comput. Sci., 17(3)(2016), 315--326).Comment: 31 pag

Unifying Entanglement and Nonlocality as a Single Concept: Quantum Wholeness

Although entanglement is widely recognized as one of the most fascinating characteristics of quantum mechanics, nonlocality remains to be a big labyrinth. The proof of existence of nonlocality is as yet not much convincing because of its strong reliance on Bell's theorem where the assumption of realism weakens the proof. We demonstrate that entanglement and quantum nonlocality are two equivalent aspects of the same quantum wholeness for spacelike separated quantum systems. This result implies that quantum mechanics is indeed a nonlocal theory and lays foundation of understanding quantum nonlocality beyond Bell's theorem.Comment: 5 pages, one figure; comments are welcom

Violation of Locality Without Inequalities for Multiparticle Perfect Correlations

We prove that for a three-qubit system in the Greenberger-Horne-Zeilinger (GHZ) state, locality per se is in conflict with the perfect GHZ correlations. The proof does not in any way use the realism assumption and can lead to a refutation of locality. We also provide inequalities that are imposed by locality. The experimental confirmation of the present reasoning may imply a genuine quantum nonlocality and will deepen our understanding of nonlocality of nature.Comment: 4 pages, 1 figure; comments are welcom

Constructing quantum circuits for maximally entangled multi-qubit states using the genetic algorithm

Numerical optimization methods such as hillclimbing and simulated annealing have been applied to search for highly entangled multi-qubit states. Here the genetic algorithm is applied to this optimization problem -- to search not only for highly entangled states, but also for the corresponding quantum circuits creating these states. Simple quantum circuits for maximally (highly) entangled states are discovered for 3, 4, 5, and 6-qubit systems; and extension of the method to systems with more qubits is discussed. Among other results we have found explicit quantum circuits for maximally entangled 5 and 6-qubit circuits, with only 8 and 13 quantum gates respectively. One significant advantage of our method over previous ones is that it allows very simple construction of quantum circuits based on the quantum states found.Comment: 15 pages, 4 figure

Calculation of entanglement for continious variable states

In this paper, we present a general formula for obtaining the reduced density opeator for any biparticle pure entangled state. Using this formula, we derive, in a compact form, the explicit formula of the entanglement for any bipartical pure entangled Gaussian state. In the case of Gaussian states, the criteria of separabelity can be naturely obtained by the formula. For non-Gaussian states, we also show the usefulness of the method presented in this paper.Comment: 4 pages, no figur