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  • Open Access

Trade-off between path entanglement and quantum sensitivity

Benjamin Lou*, Hudson A. Loughlin, and Nergis Mavalvala

  • *Contact author: benlou5@mit.edu
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Phys. Rev. Research 7, 043071 – Published 17 October, 2025

DOI: https://doi.org/10.1103/9zyr-by5p

Abstract

Entanglement often increases quantum measurement schemes’ sensitivity. However, we find that in precision measurements with zero-mean Gaussian states, such as squeezed states, entanglement between different paths degrades measurement sensitivity. We prove an inverse relationship between entanglement entropy and sensitivity for measurements of single-mode phase shifts in multimode systems and for phase shifts on both modes in two-mode systems. In the two-mode case, which models devices such as interferometers, we find that entanglement strongly degrades differential phase sensitivity. Finally, we show that minimizing entanglement between paths maximizes the phase sensitivity of N-mode systems with zero-mean Gaussian state inputs.

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Phys. Rev. Research 7, 043071– Published 17 October, 2025
  • Received 19 December 2024
  • Accepted 25 August 2025
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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