Discrimination of Non-Local Correlations

In view of the importance of quantum non-locality in cryptography, quantum computation, and communication complexity, it is crucial to decide whether a given correlation exhibits non-locality or not. As proved by Pitowski, this problem is NP-complete, and is thus computationally intractable unless N...

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Main Authors: Alberto Montina, Stefan Wolf
Format: Article
Language:English
Published: MDPI AG 2019-01-01
Series:Entropy
Subjects:
Online Access:https://www.mdpi.com/1099-4300/21/2/104
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author Alberto Montina
Stefan Wolf
author_facet Alberto Montina
Stefan Wolf
author_sort Alberto Montina
collection DOAJ
description In view of the importance of quantum non-locality in cryptography, quantum computation, and communication complexity, it is crucial to decide whether a given correlation exhibits non-locality or not. As proved by Pitowski, this problem is NP-complete, and is thus computationally intractable unless NP is equal to P. In this paper, we first prove that the Euclidean distance of given correlations from the local polytope can be computed in polynomial time with arbitrary fixed error, granted the access to a certain oracle; namely, given a fixed error, we derive two upper bounds on the running time. The first bound is linear in the number of measurements. The second bound scales with the number of measurements to the sixth power. The former holds only for a very high number of measurements, and is never observed in the performed numerical tests. We, then, introduce a simple algorithm for simulating the oracle. In all of the considered numerical tests, the simulation of the oracle contributes with a multiplicative factor to the overall running time and, thus, does not affect the sixth-power law of the oracle-assisted algorithm.
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spelling doaj.art-0014025c96174d259b339ed7304b25572022-12-22T01:56:20ZengMDPI AGEntropy1099-43002019-01-0121210410.3390/e21020104e21020104Discrimination of Non-Local CorrelationsAlberto Montina0Stefan Wolf1Facoltà di Informatica, Università della Svizzera italiana, 6900 Lugano, SwitzerlandFacoltà di Informatica, Università della Svizzera italiana, 6900 Lugano, SwitzerlandIn view of the importance of quantum non-locality in cryptography, quantum computation, and communication complexity, it is crucial to decide whether a given correlation exhibits non-locality or not. As proved by Pitowski, this problem is NP-complete, and is thus computationally intractable unless NP is equal to P. In this paper, we first prove that the Euclidean distance of given correlations from the local polytope can be computed in polynomial time with arbitrary fixed error, granted the access to a certain oracle; namely, given a fixed error, we derive two upper bounds on the running time. The first bound is linear in the number of measurements. The second bound scales with the number of measurements to the sixth power. The former holds only for a very high number of measurements, and is never observed in the performed numerical tests. We, then, introduce a simple algorithm for simulating the oracle. In all of the considered numerical tests, the simulation of the oracle contributes with a multiplicative factor to the overall running time and, thus, does not affect the sixth-power law of the oracle-assisted algorithm.https://www.mdpi.com/1099-4300/21/2/104local polytopequantum nonlocalitycommunication complexityoptimization
spellingShingle Alberto Montina
Stefan Wolf
Discrimination of Non-Local Correlations
Entropy
local polytope
quantum nonlocality
communication complexity
optimization
title Discrimination of Non-Local Correlations
title_full Discrimination of Non-Local Correlations
title_fullStr Discrimination of Non-Local Correlations
title_full_unstemmed Discrimination of Non-Local Correlations
title_short Discrimination of Non-Local Correlations
title_sort discrimination of non local correlations
topic local polytope
quantum nonlocality
communication complexity
optimization
url https://www.mdpi.com/1099-4300/21/2/104
work_keys_str_mv AT albertomontina discriminationofnonlocalcorrelations
AT stefanwolf discriminationofnonlocalcorrelations