Manipulating non-intrinsic outputs of a non-Hermitian coupled system by weak external driving

Abstract

Measurement provides access to exploring and understanding nature and finds widespread applications. It is generally believed that the weak external driving used in measurement introduces negligible disturbance to the intrinsic output of the probed system. Here, we reveal that dissipation in a non-Hermitian quantum coupled system induces interference between self-excitation and coupling-excitation spectral functions, giving rise to non-intrinsic outputs. These non-intrinsic outputs can be effectively manipulated by the ratio of weak external driving strengths applied to two channels, leading to significant phenomena: extreme suppression of dissipation by convergence effect of high-loss mode towards low-loss mode, and giant shift of resonant frequency instead of original spectral Rabi splitting. Crucially, we discover the Pythagorean relation linking eigenlevel splitting, spectral Rabi splitting and average total decay rate, enabling precise measurement of the eigenlevel splitting and coupling strength. Numerical simulations confirm that the interference outputs also exist in classical coupled systems. Our work provides a profound insight into measurement and non-Hermitian physics.