Non-Hermitian quantum sensing: fundamental limits and non-reciprocal advantages

Hoi-Kwan Lau; Aashish Clerk

doi:10.1117/12.2586713

5 March 2021 Non-Hermitian quantum sensing: fundamental limits and non-reciprocal advantages

Hoi-Kwan Lau, Aashish Clerk

Proceedings Volume 11700, Optical and Quantum Sensing and Precision Metrology; 117003J (2021) https://doi.org/10.1117/12.2586713
Event: SPIE OPTO, 2021, Online Only

Abstract

Unconventional properties of non-Hermitian systems, such exceptional points, have recently been suggested as a resource for sensing. The impact of noise and utility in quantum regimes, however, remain highly debatable. In this talk, I will introduce a full theoretical framework to analyze the performance of a dispersive quantum non-Hermitian sensor; parts of our result have been included in our recent paper Lau & Clerk, Nat. Comm. 9, 4320 (2018). Our formalism fully accounts for noise effects in both classical and quantum regimes, and also fully treats a realistic and optimal measurement protocol based on coherent driving and homodyne detection. Focusing on two-mode devices, we derive fundamental bounds on the signal-to-noise (SNR) ratio for any such sensor. We use these to demonstrate that enhanced SNR ratio does not necessarily require any proximity to an exceptional point. Furthermore, we show that non-reciprocity is a powerful resource for sensing even when quantum noise exists.

Conference Presentation

Citation Download Citation

Hoi-Kwan Lau and Aashish Clerk "Non-Hermitian quantum sensing: fundamental limits and non-reciprocal advantages", Proc. SPIE 11700, Optical and Quantum Sensing and Precision Metrology, 117003J (5 March 2021); https://doi.org/10.1117/12.2586713

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