Achieving sub-shot-noise sensing at finite temperatures

Mohammad Mehboudi, Luis A. Correa, Anna Sanpera

Research output: Contribution to journalArticleResearchpeer-review

18 Citations (Scopus)

Abstract

© 2016 American Physical Society. We investigate sensing of magnetic fields using quantum spin chains at finite temperature and exploit quantum phase crossovers to improve metrological bounds on the estimation of the chain parameters. In particular, we start by analyzing the XX spin chain. The magnetic sensitivity of this system is dictated by its magnetic susceptibility, which scales extensively (linearly) in the number of spins N. We introduce an iterative feed-forward protocol that actively exploits features of quantum phase crossovers to enable superextensive scaling of the magnetic sensitivity. Furthermore, we provide experimentally realistic observables to saturate the quantum metrological bounds. Finally, we extend our analysis on magnetic sensing to the Heisenberg XY spin chain.
Original languageEnglish
Article number042121
JournalPhysical Review A
Volume94
Issue number4
DOIs
Publication statusPublished - 21 Oct 2016

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