Buscemi nonlocality

{{Short description|Concept in quantum theory}}

{{Orphan|date=December 2024}}

Buscemi nonlocality,{{Cite journal |last=Buscemi |first=Francesco |date=2012-05-14 |title=All Entangled Quantum States Are Nonlocal |url=https://link.aps.org/doi/10.1103/PhysRevLett.108.200401 |journal=Physical Review Letters |language=en |volume=108 |issue=20 |page=200401 |doi=10.1103/PhysRevLett.108.200401 |pmid=23003127 |arxiv=1106.6095 |bibcode=2012PhRvL.108t0401B |issn=0031-9007}}{{Cite journal |last1=Massar |first1=Serge |last2=Pironio |first2=Stefano |date=2012-05-14 |title=A Closer Connection Between Entanglement and Nonlocality |url=https://physics.aps.org/articles/v5/56 |journal=Physics |language=en |volume=5 |issue=20 |pages=56 |doi=10.1103/PhysRevLett.108.200401|pmid=23003127 |arxiv=1106.6095 |bibcode=2012PhRvL.108t0401B }} a concept proposed by Francesco Buscemi in 2012, refers to a type of quantum nonlocality that arises in Bell tests where the local measurement settings are determined not by classical programs but by quantum states. Such generalized tests are called semiquantum nonlocal games. While, as the counterexample of Werner states shows, Bell nonlocality is known not to be equivalent to quantum entanglement, the latter instead turns out to be equivalent to Buscemi nonlocality: a quantum state is "Buscemi nonlocal" if and only if it is entangled.

Semiquantum nonlocal tests constitute the basis for measurement device-independent entanglement witnesses{{Cite journal |last=Branciard |first=Cyril |date=2013 |title=Measurement-Device-Independent Entanglement Witnesses for All Entangled Quantum States |url=https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.110.060405 |journal=Physical Review Letters |volume=110 |issue=6 |page=060405 |doi=10.1103/PhysRevLett.110.060405|pmid=23432224 |arxiv=1210.8037 |bibcode=2013PhRvL.110f0405B }} and their feasibility has been experimentally verified several times.{{Cite journal |last=Xu |first=Ping |date=2014 |title=Implementation of a Measurement-Device-Independent Entanglement Witness |url=https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.112.140506 |journal=Physical Review Letters |volume=112 |issue=14 |page=140506 |doi=10.1103/PhysRevLett.112.140506|pmid=24765936 |arxiv=1404.4205 |bibcode=2014PhRvL.112n0506X }}{{Cite journal |last=Verbanis |first=E. |date=2016 |title=Resource-Efficient Measurement-Device-Independent Entanglement Witness |url=https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.116.190501 |journal=Physical Review Letters |volume=116 |issue=19 |page=190501 |doi=10.1103/PhysRevLett.116.190501|pmid=27232009 |arxiv=1510.01203 |bibcode=2016PhRvL.116s0501V }}{{Cite journal |last=Li |first=Zheng-Da |date=2020 |title=Measurement-Device-Independent Entanglement Witness of Tripartite Entangled States and Its Applications |url=https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.124.160503 |journal=Physical Review Letters |volume=124 |issue=16 |page=160503 |doi=10.1103/PhysRevLett.124.160503|pmid=32383895 |bibcode=2020PhRvL.124p0503L }} Buscemi nonlocality has been given an operational interpretation similar to that of standard Bell nonlocality in the framework of quantum resource theories.{{Cite journal |last1=Lipka-Bartosik |first1=Patryk |last2=Ducuara |first2=Andrés F. |last3=Purves |first3=Tom |last4=Skrzypczyk |first4=Paul |date=2021-04-01 |title=Operational Significance of the Quantum Resource Theory of Buscemi Nonlocality |url=https://link.aps.org/doi/10.1103/PRXQuantum.2.020301 |journal=PRX Quantum |language=en |volume=2 |issue=2 |page=020301 |doi=10.1103/PRXQuantum.2.020301 |issn=2691-3399|arxiv=2010.04585 }} It also motivates the study of quantum entanglement based not on the LOCC framework, but rather on the Local Operations and Shared Randomness (LOSR) framework.{{Cite journal |last1=Schmid |first1=David |last2=Fraser |first2=Thomas C. |last3=Kunjwal |first3=Ravi |last4=Sainz |first4=Ana Belen |last5=Wolfe |first5=Elie |last6=Spekkens |first6=Robert W. |date=2023-12-04 |title=Understanding the interplay of entanglement and nonlocality: motivating and developing a new branch of entanglement theory |url=https://quantum-journal.org/papers/q-2023-12-04-1194/ |journal=Quantum |language=en |volume=7 |pages=1194 |doi=10.22331/q-2023-12-04-1194 |arxiv=2004.09194 |bibcode=2023Quant...7.1194S |issn=2521-327X}}