Enhanced sensing near a bistable phase transition point in a strongly coupled solid-state system

Phase transition physics exhibits counterintuitive phenomena and enhanced performance. Exceptional points (EPs), for example, are known to amplify perturbations in non-Hermitian systems. However, the merging of eigenstates at EPs also amplifies noise, ultimately reducing improvements in the signal-to-noise ratio (SNR). In this talk, I will discuss a hybrid quantum system composed of a nitrogen-vacancy (NV) spin ensemble coupled to a nonlinear Van der Pol oscillator. This system exhibits a bistable transition point with hallmark EP features, such as chiral state transfer and heightened sensitivity to perturbations, but crucially without the associated noise amplification. Our platform is applicable to a wide range of sensing systems and paves the way for advancements in quantum technologies leveraging phase transitions.