Dynamical evolution of an effective two-level system with PT symmetry

TL;DR

This paper explores the dynamics of PT-symmetric two-level atoms under optical and radio-frequency fields, revealing how field parameters influence symmetry phases and oscillation behaviors, with implications for understanding complex PT systems.

Contribution

It introduces a detailed analysis of PT symmetry breaking in a two-level system driven by multiple fields, highlighting controllable oscillation features and fixed point behaviors.

Findings

Rabi oscillations persist in PT-symmetric systems and are tunable by field parameters.

PT symmetry breaking occurs at exceptional points where oscillations cease.

Fixed point emergence characterizes the transition between unbroken and broken PT symmetry.

Abstract

We investigate the dynamics of parity- and time-reversal (PT ) symmetric two-energy-level atoms in the presence of two optical and a radio-frequency (rf) fields. The strength and relative phase of fields can drive the system from unbroken to broken PT symmetric regions. Compared with the Hermitian model, Rabi-type oscillation is still observed, and the oscillation characteristics are also adjusted by the strength and relative phase in the region of unbroken PT symmetry. At exception point (EP), the oscillation breaks down. To better understand the underlying properties we study the effective Bloch dynamics and find the emergence of the z components of the fixed points is the feature of the PT symmetry breaking and the projections in x-y plane can be controlled with high flexibility compared with the standard two-level system with PT symmetry. It helps to study the dynamic behavior of the complex PT symmetric model.