Magnetic field sensing beyond the standard quantum limit under the effect of decoherence

Yuichiro Matsuzaki, Simon C. Benjamin, and Joseph Fitzsimons
Phys. Rev. A 84, 012103 – Published 5 July 2011

Abstract

Entangled states can potentially be used to outperform the standard quantum limit by which every classical sensor is bounded. However, entangled states are very susceptible to decoherence, and so it is not clear whether one can really create a superior sensor to classical technology via a quantum strategy which is subject to the effect of realistic noise. This paper presents an investigation of how a quantum sensor composed of many spins is affected by independent dephasing. We adopt general noise models including non-Markovian effects, and in these noise models the performance of the sensor depends crucially on the exposure time of the sensor to the field. We have found that, by choosing an appropriate exposure time within the non-Markovian time region, an entangled sensor does actually beat the standard quantum limit. Since independent dephasing is one of the most typical sources of noise in many systems, our results suggest a practical and scalable approach to beating the standard quantum limit.

  • Figure
  • Received 14 March 2011

DOI:https://doi.org/10.1103/PhysRevA.84.012103

©2011 American Physical Society

Authors & Affiliations

Yuichiro Matsuzaki1, Simon C. Benjamin1,2,*, and Joseph Fitzsimons2

  • 1Department of Materials, University of Oxford, OX1 3PH, United Kingdom
  • 2Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore 117543

  • *s.benjamin@qubit.org

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Vol. 84, Iss. 1 — July 2011

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