2018/05/30 by Hoi-Kwan Lau, Aashish A. Clerk · 7 citations
Engineering · Mathematics · Physics and Astronomy · #Advanced Fiber Laser Technologies #Computer science #Electrical engineering #Engineering #Hermitian matrix #Homodyne detection #Mathematics #Mechanical and Optical Resonators #Noise (video) #Parametric statistics #Physics #Quantum #Quantum Mechanics and Non-Hermitian Physics #Quantum mechanics #Reciprocal #Reciprocity (cultural anthropology) #Statistical physics #Topology (electrical circuits) #cond-mat.mes-hall #physics.optics #quant-ph
paper · pdf · doi:10.1038/s41467-018-06477-7
published as Nature Communications 9, 4320 (2018)
arxiv created 2018/05/30 · openalex publication_date 2018/10/11 · arxiv updated 2018/10/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
Unconventional properties of non-Hermitian systems, such as the existence of exceptional points, have recently been suggested as a resource for sensing. The impact of noise and utility in quantum regimes however remains unclear. In this work, we analyze the parametric-sensing properties of linear coupled-mode systems that are described by effective non-Hermitian Hamiltonians. Our analysis 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 power and signal-to-noise ratio for any such sensor. We use these to demonstrate that enhanced signal power requires gain, but not necessarily any proximity to an exceptional point. Further, when noise is included, we show that nonreciprocity is a powerful resource for sensing: it allows one to exceed the fundamental bounds constraining any conventional, reciprocal sensor.