dc.contributor.author Sokolovski, D. dc.contributor.author Rusconi, S. dc.contributor.author Brouard, S. dc.contributor.author Akhmatskaya, E. dc.date.accessioned 2017-04-24T15:14:27Z dc.date.available 2017-04-24T15:14:27Z dc.date.issued 2017-04-10 dc.identifier.issn 2469-9926 dc.identifier.uri http://hdl.handle.net/20.500.11824/668 dc.description.abstract Imposing restrictions on the Feynman paths of the monitored system has in the past been proposed as a universal model-free approach to continuous quantum measurements. Here we revisit this proposition and demonstrate that a Gaussian restriction, resulting in a sequence of many highly inaccurate (weak) von Neumann measurements, is not sufficiently strong to ensure proximity between a readout and the Feynman paths along which the monitored system evolves. Rather, in the continuous limit, the variations of a typical readout become much larger than the separation between the eigenvalues of the measured quantity. Thus, a typical readout is not represented by a nearly constant curve, correlating with one of the eigenvalues of the measured quantity $\hat{A}$, even when decoherence or Zeno effect is achieved for the observed two-level system, and does not point directly to the system's final state. We show that the decoherence in a free'' system can be seen as induced by a Gaussian random walk with a drift, eventually directing the system towards one of the eigenstates of $\hat{A}$. A similar mechanism appears to be responsible for the Zeno effect in a driven system, when its Rabi oscillations are quenched by monitoring. Alongside the Gaussian case, which can only be studied numerically, we also consider a fully tractable model with a hard wall'' restriction and show the results to be similar. en_US dc.description.sponsorship MINECO, Fondo Europeo de Desarrollo Regional FEDER, Grant No. FIS2015-67161-P (MINECO/FEDER) (D.S.), MINECO Grant No. SVP-2014-068451 (S.R.), MINECO Grant No. MTM2013-46553-C3-1-P (E.A.), SGI/IZOSGIker UPV/EHU, i2BASQUE academic network, en_US dc.format application/pdf en_US dc.language.iso eng en_US dc.rights Reconocimiento-NoComercial-CompartirIgual 3.0 España en_US dc.rights.uri http://creativecommons.org/licenses/by-nc-sa/3.0/es/ en_US dc.subject Restrictions on Feynman paths en_US dc.subject weak von Neumann measurements en_US dc.subject continuous limit en_US dc.subject Zeno effect en_US dc.subject Rabi oscillations en_US dc.title Reexamination of continuous fuzzy measurement on two-level systems en_US dc.type info:eu-repo/semantics/article en_US dc.identifier.doi 10.1103/PhysRevA.95.042111 dc.relation.publisherversion https://journals.aps.org/pra/abstract/10.1103/PhysRevA.95.042111 en_US dc.relation.projectID ES/1PE/SEV-2013-0323 en_US dc.relation.projectID ES/1PE/MTM2016-76329-R en_US dc.relation.projectID EUS/BERC/BERC.2014-2017 en_US dc.rights.accessRights info:eu-repo/semantics/openAccess en_US dc.type.hasVersion info:eu-repo/semantics/publishedVersion en_US dc.journal.title PHYSICAL REVIEW A en_US
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