Exceptional sensitivity near the bistable transition point of a hybrid quantum system

Fuente: arXiv
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Main Authors: Wang, Hanfeng, Jacobs, Kurt, Fahey, Donald, Hu, Yong, Englund, Dirk R., Trusheim, Matthew E.
Format: Preprint
Published: 2025
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_version_ 1866911052984221696
author Wang, Hanfeng
Jacobs, Kurt
Fahey, Donald
Hu, Yong
Englund, Dirk R.
Trusheim, Matthew E.
author_facet Wang, Hanfeng
Jacobs, Kurt
Fahey, Donald
Hu, Yong
Englund, Dirk R.
Trusheim, Matthew E.
contents Phase transitions can dramatically alter system dynamics, unlocking new behavior and improving performance. Exceptional points (EPs), where the eigenvalues and corresponding eigenvectors of a coupled linear system coalesce, are particularly relevant for sensing applications as they can increase sensor response to external perturbations to a range of phenomena from optical phase shifts to gravitational waves. However, the coalescence of eigenstates at linear EPs amplifies noise, negating the signal-to-noise ratio (SNR) enhancement. Here, we overcome this limitation using nonlinearity, which exhibits exceptional SNR around a bistable transition point (BP). We couple a state-of-the-art diamond quantum sensor to a nonlinear Van der Pol oscillator, forming a self-oscillating hybrid system that exhibits both a single-valued and bistable phase. The boundaries between these phases are marked by both adiabatic and deterministic non-adiabatic transitions that enable chiral state switching and state coalescence at the BP. Crucially, NV magnetometry performed near the BP exhibits a 17x enhancement in SNR, achieving a record sensitivity of 170 fT/\sqrt{Hz}. This result surpasses the sensitivity limit of an ideal, thermally-limited electron magnetometer and resolves a long-standing debate regarding EP-like physics in advanced quantum sensing.
format Preprint
id arxiv_https___arxiv_org_abs_2507_09691
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Exceptional sensitivity near the bistable transition point of a hybrid quantum system
Wang, Hanfeng
Jacobs, Kurt
Fahey, Donald
Hu, Yong
Englund, Dirk R.
Trusheim, Matthew E.
Quantum Physics
Phase transitions can dramatically alter system dynamics, unlocking new behavior and improving performance. Exceptional points (EPs), where the eigenvalues and corresponding eigenvectors of a coupled linear system coalesce, are particularly relevant for sensing applications as they can increase sensor response to external perturbations to a range of phenomena from optical phase shifts to gravitational waves. However, the coalescence of eigenstates at linear EPs amplifies noise, negating the signal-to-noise ratio (SNR) enhancement. Here, we overcome this limitation using nonlinearity, which exhibits exceptional SNR around a bistable transition point (BP). We couple a state-of-the-art diamond quantum sensor to a nonlinear Van der Pol oscillator, forming a self-oscillating hybrid system that exhibits both a single-valued and bistable phase. The boundaries between these phases are marked by both adiabatic and deterministic non-adiabatic transitions that enable chiral state switching and state coalescence at the BP. Crucially, NV magnetometry performed near the BP exhibits a 17x enhancement in SNR, achieving a record sensitivity of 170 fT/\sqrt{Hz}. This result surpasses the sensitivity limit of an ideal, thermally-limited electron magnetometer and resolves a long-standing debate regarding EP-like physics in advanced quantum sensing.
title Exceptional sensitivity near the bistable transition point of a hybrid quantum system
topic Quantum Physics
url https://arxiv.org/abs/2507.09691