Collective Radiance of Giant Atoms in Non-Markovian Regime

TL;DR

This paper explores the non-Markovian dynamics of two giant atoms in a 1D waveguide, revealing phenomena like super-superradiance, bound states in continuum, and controllable photon trapping, advancing understanding of complex quantum systems.

Contribution

It provides exact analytical solutions for collective radiance in non-Markovian regimes, highlighting phenomena beyond traditional models and introducing mechanisms for photon control in giant atom systems.

Findings

Decay rates surpass Dicke model predictions

Existence of multiple bound states in continuum

Photon/phonon trapping and re-release mechanisms

Abstract

We investigate the non-Markovian dynamics of two giant artificial atoms interacting with a continuum of bosonic modes in a one-dimensional (1D) waveguide. Based on the diagrammatic method, we present the exact analytical solutions, which predict the rich phenomena of collective radiance. For the certain collective states, the decay rates are found to be far beyond that predicted in the the Dicke model and standard Markovian framework, which indicates the occurrence of super-superradiance. The superadiance-to-subradiance transition could be realized by adjusting the exchange symmetry of giant atoms. Moreover, there exists multiple bound states in continuum (BICs), with photons/phonons bouncing back and forth in the cavity-like geometries formed by the coupling points. The trapped photons/phonons in the BICs can also be re-released conveniently by changing the energy level splitting of giant atoms. The mechanism relies on the joint effects of the coherent time-delayed feedback and the interference between the coupling points of giant atoms. This work fundamentally broadens the fields of giant atom collective radiance by introducing non-Markovianity. It also paves the way for a clean analytical description of nonlinear open quantum system with more complex retardation.