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Adiabatic Ramsey interference in a pseudo-Hermitian two-level system

by Jing Dong, Xiao-Lin Li, Fu-Quan Dou and Wen-Yuan Wang

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Authors (as registered SciPost users):

Wen-Yuan Wang

Abstract

Ramsey interferometry involves two separate pulse fields with a controlled free evolution period between them, exploiting the coherent superposition of two distinct quantum states and their subsequent phase accumulation to manifest interference patterns. This technique has implications across quantum mechanics, quantum optics, and quantum information processing. The pseudo-Hermitian systems have garnered significant attention due to their unconventional properties, such as the existence of exceptional points (EPs) and parity-time ($\mathcal{PT}$) symmetry. Here, we investigate adiabatic Ramsey interference in a two-level pseudo-Hermitian system characterized by nonlinear self-interaction and nonreciprocal coupling between the levels, unveiling novel phenomena that transcends the traditional Hermitian frameworks. We implement a Ramsey interferometer that incorporates two temporally separated Rosen-Zener pulses. By harnessing the properties of the pseudo-Hermitian system, such as $\mathcal{PT}$ symmetric phase transition and associated EPs, we demonstrate that the interference pattern can be generated and controlled, corresponding to coherent control of the quantum states. In particular, the interference pattern observed vanishes as the system transitions from a $\mathcal{PT}$ symmetric phase to a broken-symmetry phase, which underscores the interplay between the symmetry properties of the system and the manifestation of quantum coherence. Our findings provide a theoretical perspective for the manipulation of quantum states in pseudo-Hermitian systems.