Geometric phase of a two-level atom near a dielectric nanosphere out of thermal equilibrium

TL;DR

This paper investigates how the geometric phase of a two-level atom is affected by a dielectric nanosphere environment out of thermal equilibrium, revealing enhancement effects and bounds related to non-equilibrium conditions.

Contribution

It provides an analytical and numerical analysis of the geometric phase in non-equilibrium environments, highlighting the role of evanescent waves and local density of states.

Findings

GP is enhanced by surface evanescent waves at resonance

GP out of thermal equilibrium is bounded by equilibrium cases

Temperature differences influence GP at moderate distances

Abstract

We study the geometric phase (GP) of a two-level atom coupled to an environment composed of free space and a dielectric nanosphere in thermal and out of thermal equilibrium. We analytically and numerically analyze the optical properties and loss of the dielectric medium, along with the non-equilibrium effects of the environment on the GP. In the weak coupling limit, we find that the correction to the GP depends on the partial local density of photonic states at the atom position, and an effective parameter that emerges out of the non-equilibrium configuration of the system. The GP exhibits a significant enhancement due to the excitation of evanescent surface waves at its resonance frequency. It is shown that the GP acquired by the atomic system out of thermal equilibrium is always bounded between the thermal-equilibrium counterparts. Furthermore, the temperature difference between the nanosphere and free space can play an important role in the GP only at moderate atomic distances from the nanosphere. Our results elegantly demonstrate properties of the GP near material media that can support phononic modes and pave the way for further research of GP as a resource for quantum computation.