Universal Quantum Magnetometry with Spin States at Equilibrium

Filippo Troiani and Matteo G. A. Paris
Phys. Rev. Lett. 120, 260503 – Published 29 June 2018
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Abstract

We address metrological protocols for the estimation of the intensity and the orientation of a magnetic field, and show that quantum-enhanced precision may be achieved by probing the field with an arbitrary spin at thermal equilibrium. A general expression is derived for the ultimate achievable precision, as given by the quantum Fisher information. The optimal observable is shown to correspond to the spin projection along a temperature-dependent direction, and allows a maximally precise parameter estimation also through ensemble measurements. Finally, we prove the robustness of our scheme against deviations of the measured spin projection from optimality.

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  • Received 2 November 2017

DOI:https://doi.org/10.1103/PhysRevLett.120.260503

© 2018 American Physical Society

Physics Subject Headings (PhySH)

Quantum Information, Science & TechnologyAtomic, Molecular & OpticalCondensed Matter, Materials & Applied Physics

Authors & Affiliations

Filippo Troiani1,* and Matteo G. A. Paris2,3,†

  • 1Centro S3, CNR-Istituto di Nanoscienze, I-41125 Modena, Italy
  • 2Quantum Technology Lab, Dipartimento di Fisica dell’Università degli Studi di Milano, I-20133 Milano, Italy
  • 3INFN, Sezione di Milano, I-20133 Milano, Italy

  • *filippo.troiani@nano.cnr.it
  • matteo.paris@fisica.unimi.it

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Issue

Vol. 120, Iss. 26 — 29 June 2018

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