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Non-Markovian delay-assisted sensing with waveguide-coupled quantum emitters

Prajit Dhara1,2,3,*, Isack Padilla1,†, Saikat Guha1,3,‡, Annyun Das1,4,§, and Kanu Sinha1,4,∥

  • *Contact author: prajit.dhara@rtx.com
  • †Contact author: iacpad0795@arizona.edu
  • ‡Contact author: saikat@umd.edu
  • §Contact author: annyun@arizona.edu
  • ∥Contact author: kanu@arizona.edu
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Phys. Rev. Research 8, 043138 – Published 6 November, 2026

DOI: https://doi.org/10.1103/m9nn-cgww

Abstract

We show that in a minimal setup of two waveguide-coupled quantum emitters, separated by long distances and subject to an external field, time-delayed feedback can be a resource for sensing field gradients. While the field gradient induces a detuning between the emitters, the large interatomic separations render the system dynamics non-Markovian. We show that the quantum Fisher information for estimating the detuning parameter, and thereby the field gradient, is enhanced in the presence of non-Markovian delay. Such an enhancement can be attributed to the formation of atom-photon quasibound states that enable the field to interact with the emitters for longer times, thereby gaining more information about their relative detunings. Additionally, in the presence of delay, the interaction between the emitters is mediated via multiple spectral modes of the field, further enhancing the sensing capabilities of the system. Our results establish non-Markovian time-delayed feedback and multimode reservoirs as a resource for distributed quantum sensing with waveguide-coupled quantum emitters.

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Phys. Rev. Research 8, 043138– Published 6 November, 2026
  • Received 21 May 2026
  • Accepted 23 October 2026
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