arXiv subjects

Ping-Xing Chen

Publications and source records attributed to Ping-Xing Chen.

44 records · Page 3Linked to original sources

arXiv2007

More Detailed Descriptions of Locality and Realism

Many experiments have shown that locality-realism theory is at variance with quantum mechanics predictions. Although locality and realism, which are two different conceptions, are given respective definition, the descriptions of the both are a little of abstract when they are applied to real experimental situations. The abstract descriptions result in difficulty for one to judge whether the variance come from locality or realism or both. Here we provide more detailed descriptions of locality and realism, and show that any system being in a pure state or a non-maximally mixed state has property of non-realism. We also present experimental schemes feasible under current technologies to test the non-locality realsim. The connections between non-locality and entanglement and correlation are also discussed.

quant-ph↗

arXiv2005

Local Distinguishability and Schmidt Number of Orthogonal States

Now, the known ensembles of orthogonal states which are distinguishable by local operators and classical communication (LOCC) satisfy the condition that the sum of Schmidit numbers of the orthogonal states is not bigger than the dimensions of the whole space. A natural question is whether an arbitary ensembles of LOCC-distinguishable orthogonal states satisfies the condition. We first show that, in this paper, the answer is positive. Then we generalize it into multipartite systems, and show that a necessary condition for LOCC-distinguishability of multipartite orthogonal quantum states is that the sum of the least numbers of the product states (For bipartite system, the least number of product states is Schmidit number) of the orthogonal states is not bigger than the dimensions of the Hilbert space of the multipartite system. This necessary condition is very simple and general, and one can get many cases of indistinguishability by it. It means that the least number of the product states acts an important role in distinguishablity of states, and implies that the least number of the product states may be an good manifestion of quantum nonlocality in some sense. In fact, entanglement emphases the "amount" of nonlocality, but the least number of the product states emphases the types of nonlocality. For example, the known W states and GHZ states have different least number of the product states, and are different in type.

quant-ph↗

arXiv2003

Local distinguishability of quantum states and the distillation of entanglement

This paper tries to probe the relation between the local distinguishability of orthogonal quantum states and the distillation of entanglement. An new interpretation for the distillation of entanglement and the distinguishability of orthogonal quantum states in terms of information is given, respectively. By constraining our discussion on a special protocol we give a necessary and sufficient condition for the local distinguishability of the orthogonal pure states, and gain the maximal yield of the distillable entanglement. It is shown that the information entropy, the locally distinguishability of quantum states and the distillation of entanglement are closely related.

quant-ph↗

arXiv2002

A Necessary And Sufficient Condition of Distillability with unite fidelity from Finite Copies of a Mixed State: The Most Efficient Purification Protocol

It is well known that any entangled mixed state in $2\otimes 2$ systems can be purified via infinite copies of the mixed state. But can one distill a pure maximally entangled state from finite copies of a mixed state in any bipartite system by local operation and classical communication? This is more meaningful in practical application. We give a necessary and sufficient condition of this distillability. This condition can be expressed as: there exists distillable-subspaces. According to this condition, one can judge whether a mixed state is distillable or not easily. We also analyze some properties of distillable-subspaces, and discuss the most efficient purification protocols. Finally, we discuss the distillable enanglement of two-quibt system for the case of finite copies.

quant-ph↗

arXiv2002

Criterion for distinguishability of arbitrary bipartite orthogonal states

In this paper we present a necessary and sufficient condition of distinguishability of bipartite quantum states. It is shown that the operators to reliably distinguish states need only rounds of projective measurements and classical comunication. We also present a necessary condition of distinguishability of bipartite quantum states which is simple and general. With this condition one can get many cases of indistinguishability. The conclusions may be useful in understanding the essence of nonlocality and calculating the distillable entanglement and the bound of distillable entanglement.

quant-ph↗

arXiv2001

Impossibility Criterion for Obtaining Pure Entangled States From Mixed States By Purifying Protocols

Purifying noisy entanglement is a protocol which can increase the entanglement of a mixed state (as a source)at expense of the entanglement of others(as an ancilla)by collective measurement. A protocol with which one can get a pure entangled state from a mixed state is defined as purifying mixed states. We address a basic question: can one get a pure entangled state from a mixed state? We give a necessary and sufficient condition of purifying a mixed state by fit local operations and classical communication and show that for a class of source states and ancilla states in arbitrary bipartite systems purifying mixed states is impossible by finite rounds of purifying protocols. For $2\otimes 2$ systems, it is proved that arbitrary states cannot be purified by individual measurement. The possible application and meaning of the conclusion are discussed.

quant-ph↗

arXiv2001

Reply to Comment

In the comment(quant-ph/0103003) Eggeling,Vollbrecht and Wolf suspect our method in quant-ph/0102133 is not practical. Here we explain our result and method and show that our example can tell one how to judge a separable state, and so our method is practical, at least for many mixed states.

quant-ph↗

arXiv2001

Necessary And Sufficient Condition of Separability of Any System

The necessary and sufficient condition of separability of a mixed state of any systems is presented, which is practical in judging the separability of a mixed state. This paper also presents a method of finding the disentangled decomposition of a separable mixed state.

quant-ph↗