Quantum Noise Suppression in Non-Hermitian Resonators at Exceptional Point

TL;DR

This paper analyzes how quantum noise affects non-Hermitian resonators at an exceptional point, revealing conditions under which quantum noise can be suppressed to improve system stability and signal quality.

Contribution

It provides an exact analytic solution for quantum noise effects in non-Hermitian resonators at exceptional points using the Lindblad master equation.

Findings

Quantum noise significantly impacts the system's response in the $ ext{PT}$-symmetric regime.

The system remains stable outside the $ ext{PT}$-symmetric regime within a certain parameter range.

Increasing the external field can mitigate quantum noise effects on the signal-to-noise ratio.

Abstract

We investigate the impact of quantum noise on non-Hermitian resonators at an exceptional point (EP). The system's irreversible Markovian dynamics is modeled using the Lindblad master equation, which accounts for the incoherent pump, radiative losses, and external monochromatic field. An exact analytic solution is derived in the form of the characteristic function of the Husimi distribution, enabling the calculation of all quantum mechanical observables associated with the bosonic degrees of freedom. Our analysis reveals that quantum noise strongly influences the system's response when the system exhibits $\mathcal{P}\mathcal{T}$-symmetry. Out of the $\mathcal{P}\mathcal{T}$-symmetric regime, however, the system demonstrates stability within a specific parametric domain, where the effects of quantum noise on the signal-to-noise ratio can be mitigated by increasing the external field.