scholarly journals Quantum nonlocality without entanglement depending on nonzero prior probabilities in optimal unambiguous discrimination

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Donghoon Ha ◽  
Jeong San Kim
Keyword(s):  
Quantum State ◽  
Quantum States ◽  
Quantum Nonlocality ◽  
Quantum State Discrimination ◽  
Classical Communication ◽  
Minimum Error ◽  
Prior Probabilities ◽  
Separable States ◽  
Unambiguous Discrimination ◽  
State Discrimination

AbstractNonlocality without entanglement(NLWE) is a nonlocal phenomenon that occurs in quantum state discrimination of multipartite separable states. In the discrimination of orthogonal separable states, the term NLWE is used when the quantum states cannot be discriminated perfectly by local operations and classical communication. In this case, the occurrence of NLWE is independent of nonzero prior probabilities of quantum states being prepared. Recently, it has been found that the occurrence of NLWE can depend on nonzero prior probabilities in minimum-error discrimination of nonorthogonal separable states. Here, we show that even in optimal unambiguous discrimination, the occurrence of NLWE can depend on nonzero prior probabilities. We further show that NLWE can occur regardless of nonzero prior probabilities, even if only one state can be locally discriminated without error. Our results provide new insights into classifying sets of multipartite quantum states in terms of quantum state discrimination.

scholarly journals Optimal Unambiguous Discrimination And Quantum Nonlocality Without Entanglement: Locking And Unlocking By Post-Measurement Information

2021 ◽  
Author(s):  
Donghoon Ha ◽  
Jeong San Kim
Keyword(s):  
Quantum Nonlocality ◽  
Measurement Information ◽  
Minimum Error ◽  
Separable States ◽  
Unambiguous Discrimination ◽  
State Discrimination

Abstract The phenomenon of nonlocality without entanglement(NLWE) arises in discriminating multi-party quantum separable states. Recently, it has been found that the post-measurement information about the prepared subensemble can lock or unlock NLWE in minimum-error discrimination of non-orthogonal separable states. Thus it is natrual to ask whether the availability of the post-measurement information can influence on the occurrence of NLWE even in other state-discrimination stratigies. Here, we show that the post-measurement information can be used to lock as well as unlock the occurence of NLWE in terms of optimal nambiguous discrimination. Our results can provide a useful application for hiding or sharing information based on non-orthogonal separable states.

scholarly journals Understanding of Various Type of Unambiguous Discrimination in View of Coherence Distribution

Entropy ◽  
2020 ◽  
Vol 22 (12) ◽  
pp. 1422
Author(s):  
Min Namkung ◽  
Younghun Kwon
Keyword(s):  
Quantum Information ◽  
Quantum State ◽  
Quantum Key Distribution ◽  
Key Distribution ◽  
Quantum States ◽  
Quantum State Discrimination ◽  
Mixed States ◽  
Generalized Measurement ◽  
Unambiguous Discrimination ◽  
State Discrimination

Unambiguous quantum state discrimination is a strategy where the conclusive result can always be trusted. This strategy is very important, since it can be used for various quantum information protocols, including quantum key distribution. However, in the view of quantumness, it is not clear what is going on in performing unambiguous quantum state discrimination. To answer the question, we investigate coherence distribution when unambiguous discrimination is performed by generalized measurement. Specially, we study coherence distribution in three cases, which consist of unambiguous quantum state discrimination, sequential quantum state discrimination, and assisted optimal discrimination, which are considered to be a family of unambiguous quantum state discrimination. In this investigation, we show that the structure of generalized measurements performing various types of unambiguous quantum state discrimination can be understood in terms of coherence distribution. Our result is not limited to the discrimination of two pure quantum states, but it is extended to the discrimination of two mixed states.

scholarly journals Quantum nonlocality without entanglement: explicit dependence on prior probabilities of nonorthogonal mirror-symmetric states

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Donghoon Ha ◽  
Younghun Kwon
Keyword(s):  
Party System ◽  
Functional Dependence ◽  
Quantum States ◽  
Quantum Nonlocality ◽  
Explicit Dependence ◽  
Classical Communication ◽  
Minimum Error ◽  
Prior Probabilities ◽  
Quantum Ensemble ◽  
Perfect Discrimination

AbstractIn the case of a multi-party system, through local operations and classical communication (LOCC), each party may not perform perfect discrimination of quantum states that are separable and orthogonal. This property of quantum ensemble is called “nonlocality without entanglement” since each local party has a limit to full information of given quantum states. When this property is extended to the case of minimum-error discrimination, one can see that it is revealed when a nonlocal measurement provides more information about the unentangled states than LOCC does. One may infer the fact that the property depends on quantum states composing the quantum ensemble. However, an essential but unsettled question about the property is whether an explicit dependence on prior probabilities in terms of minimum-error discrimination could be shown in nonlocality without entanglement. In a simple term, one can ask whether different quantum ensembles made of the same separable quantum states could exhibit explicitly different behavior of the nonlocality. We answer this question in the positive, and we furthermore provide the explicit functional dependence of guessing probability on prior probabilities for the mirror-symmetric ensemble.

scholarly journals Support Vector Machines with Quantum State Discrimination

2021 ◽  
Vol 3 (3) ◽  
pp. 482-499
Author(s):  
Roberto Leporini ◽  
Davide Pastorello
Keyword(s):  
Support Vector Machines ◽  
Quantum State ◽  
Quantum States ◽  
Support Vector ◽  
Classification Algorithms ◽  
Quantum State Discrimination ◽  
Classification Problems ◽  
Density Operators ◽  
State Discrimination ◽  
Vector Machines

We analyze possible connections between quantum-inspired classifications and support vector machines. Quantum state discrimination and optimal quantum measurement are useful tools for classification problems. In order to use these tools, feature vectors have to be encoded in quantum states represented by density operators. Classification algorithms inspired by quantum state discrimination and implemented on classic computers have been recently proposed. We focus on the implementation of a known quantum-inspired classifier based on Helstrom state discrimination showing its connection with support vector machines and how to make the classification more efficient in terms of space and time acting on quantum encoding. In some cases, traditional methods provide better results. Moreover, we discuss the quantum-inspired nearest mean classification.

scholarly journals Almost minimum error discrimination of N-ary weak coherent states by Jaynes-Cummings Hamiltonian dynamics

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Min Namkung ◽  
Younghun Kwon
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Quantum State ◽  
Coherent States ◽  
Quantum Information Processing ◽  
Hamiltonian Dynamics ◽  
Quantum State Discrimination ◽  
Minimum Error ◽  
State Discrimination

AbstractQuantum state discrimination of coherent states has been one of important problems in quantum information processing. Recently, R. Han et al. showed that minimum error discrimination of two coherent states can be nearly done by using Jaynes-Cummings Hamiltonian. In this paper, based on the result of R. Han et al., we propose the methods where minimum error discrimination of more than two weak coherent states can be nearly performed. Specially, we construct models which can do almost minimum error discrimination of three and four coherent states. Our result can be applied to quantum information processing of various coherent states.

SHARING OF D-DIMENSIONAL QUANTUM STATES

2012 ◽  
Vol 10 (02) ◽  
pp. 1250003 ◽  
Author(s):  
OMAR JIMÉNEZ ◽  
CARLOS MUÑOZ ◽  
ANDREI B. KLIMOV ◽  
ALDO DELGADO
Keyword(s):  
Quantum State ◽  
Success Probability ◽  
Quantum States ◽  
Quantum State Sharing ◽  
Quantum Channels ◽  
Quantum State Discrimination ◽  
State Discrimination ◽  
Ideal Quantum

We propose a scheme for the deterministic sharing arbitrary qudit states among three distant parties and characterize the set of ideal quantum channels. We also show that the use of non-ideal quantum channels for quantum state sharing can be related to the problem of quantum state discrimination. This allows us to formulate a protocol which leads to perfect quantum state sharing with a finite success probability.

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