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Characterization of a quasistatic environment with a qubit

MetadataDetails
Publication Date2019-06-20
JournalPhysical review. A/Physical review, A
AuthorsFattah Sakuldee, Łukasz Cywiński
InstitutionsPolish Academy of Sciences, Institute of Physics
Citations8

We consider a qubit initalized in a superposition of its pointer states,\nexposed to pure dephasing due to coupling to a quasi-static environment, and\nsubjected to a sequence of single-shot measurements projecting it on chosen\nsuperpositions. We show how with a few of such measurements one can\nsignificantly diminish one’s ignorance about the environmental state, and how\nthis leads to increase of coherence of the qubit interacting with a properly\npost-selected environmental state. We give theoretical results for the case of\na quasi-static environment that is a source of an effective field of Gaussian\nstatistics acting on a qubit, and for a nitrogen-vacancy center qubit coupled\nto a nuclear spin bath, for which the Gaussian model applies qualitatively\nprovided one excludes from the environment nuclei that are strongly coupled to\nthe qubit. We discuss the reason for which the most probable sequences of\nmeasurement results are the ones consisting of identical outcomes, and in this\nway we shed light on recent experiment (D. D. Bhaktavatsala Rao et al.,\narXiv:1804.07111) on nitrogen-vacancy centers.\n

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