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Entangled quantum probes for dynamical environmental noise

Matteo A. C. Rossi and Matteo G. A. Paris
Phys. Rev. A 92, 010302(R) – Published 28 July 2015
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Abstract

We address the use of entangled qubits as quantum probes to characterize the noise induced by complex environments. In particular, we show that a joint measurement on entangled probes can improve estimation of the correlation time for a broad class of environmental noises compared to sequential strategies involving single-qubit preparation. The enhancement appears when the noise is faster than a threshold value, a regime which may always be achieved by tuning the coupling between the quantum probe and the environment inducing the noise. Our scheme exploits time-dependent sensitivity of quantum systems to decoherence and does not require dynamical control on the probes. We derive the optimal interaction time and the optimal probe preparation, showing that it corresponds to multiqubit Greenberger-Horne-Zeilinger states when entanglement is useful. We also show the robustness of the scheme against depolarization or dephasing of the probe, and discuss simple measurements approaching optimal precision.

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  • Received 17 March 2015

DOI:https://doi.org/10.1103/PhysRevA.92.010302

©2015 American Physical Society

Authors & Affiliations

Matteo A. C. Rossi* and Matteo G. A. Paris

  • Dipartimento di Fisica, Università degli Studi di Milano, 20133 Milano, Italy

  • *matteo.rossi@unimi.it
  • matteo.paris@fisica.unimi.it

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Issue

Vol. 92, Iss. 1 — July 2015

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