Giant atoms coupled to waveguide: Continuous coupling and multiple excitations

TL;DR

This paper introduces a stochastic Schrödinger equation approach to study giant atoms coupled to waveguides, focusing on continuous coupling and multiple excitations, revealing new interference effects and enabling analysis of complex photon processes.

Contribution

The paper develops a novel SSE method that captures continuous coupling effects and handles multiple excitations without increased complexity, advancing the study of giant atom-waveguide systems.

Findings

Continuous coupling weakens interference effects compared to discrete coupling.

The SSE approach directly reflects photon emission, absorption, and time-delay processes.

It naturally manages multiple excitations, facilitating analysis of multi-excitation initial states.

Abstract

We propose a stochastic Schr\"odinger equation (SSE) approach to investigate the dynamics of giant atoms coupled to a waveguide, addressing two critical gaps in existing research, namely insufficient exploration on continuous coupling and multiple excitations. A key finding is that continuous coupling, unlike discrete coupling at finite points, breaks the constant phase difference condition, thereby weakening the interference effects in giant atom-waveguide systems. In addition, a key technical advantage of the SSE approach is that auto- and cross-correlation functions can directly reflect the complex photon emission/absorption processes and time-delay effects in giant atom-waveguide systems. Moreover, the SSE approach also naturally handles multiple excitations, without increasing equation complexity as the number of excitations grows. This feature enables the investigation of multi-excitation initial states of the waveguide, such as thermal and squeezed initial states. Overall, our approach provides a powerful tool for studying the dynamics of giant atoms coupled to waveguide, particularly for continuous coupling and multi-excitation systems.