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dc.contributor.authorSun, Won Kyu Calvin
dc.contributor.authorCappellaro, Paola
dc.date.accessioned2020-05-05T19:54:01Z
dc.date.available2020-05-05T19:54:01Z
dc.date.issued2020-01-13
dc.identifier.issn2469-9926
dc.identifier.issn2469-9934
dc.identifier.urihttps://hdl.handle.net/1721.1/125030
dc.description.abstractEntanglement, while being critical in many quantum applications, is difficult to characterize experimentally. While entanglement witnesses based on the fidelity to the target entangled state are efficient detectors of entanglement, they in general underestimate the amount of entanglement due to local unitary errors during state preparation and measurement. Therefore, to detect entanglement more robustly in the presence of such control errors, we introduce a 'subspace' witness that detects a broader class of entangled states with strictly larger violation than the conventional state-fidelity witness at the cost of additional measurements, while remaining more efficient with respect to state tomography. We experimentally demonstrate the advantages of the subspace witness by generating and detecting entanglement with a hybrid, two-qubit system composed of electronic spins in diamond. We further extend the notion of the subspace witness to specific genuine multipartite entangled (GME) states detected by the state witness, such as GHZ, W, and Dicke states, and motivate the choice of the metric based on quantum information tasks, such as entanglement-enhanced sensing. In addition, as the subspace witness identifies the many-body coherences of the target entangled state, it facilitates (beyond detection) lower-bound quantification of entanglement via generalized concurrences. We expect that the straightforward and efficient implementation of subspace witnesses would be beneficial in detecting specific GME states in noisy, intermediate-scale quantum processors with a hundred qubits.en_US
dc.language.isoen
dc.publisherAmerican Physical Society (APS)en_US
dc.relation.isversionof10.1103/physreva.101.012319en_US
dc.rightsArticle is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.en_US
dc.sourceAPSen_US
dc.titleImproved entanglement detection with subspace witnessesen_US
dc.typeArticleen_US
dc.identifier.citationSun, Won Kyu Calvin, Alexandre Cooper and Paola Cappellaro. "Improved entanglement detection with subspace witnesses." Physical review. A. Volume 101 (2020) © 2020 The Author(s)en_US
dc.contributor.departmentMassachusetts Institute of Technology. Department of Nuclear Science and Engineeringen_US
dc.relation.journalPhysical review. A.en_US
dc.eprint.versionFinal published versionen_US
dc.type.urihttp://purl.org/eprint/type/JournalArticleen_US
eprint.statushttp://purl.org/eprint/status/PeerRevieweden_US
dc.date.updated2020-02-20T18:35:00Z
dspace.date.submission2020-02-20T18:35:02Z
mit.journal.volume101en_US
mit.journal.issue1en_US
mit.licensePUBLISHER_POLICY
mit.metadata.statusComplete


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