Superconducting giant atom waveguide QED: Quantum Zeno and Anti-Zeno effects in ultrastrong coupling regime

TL;DR

This paper explores how a superconducting giant atom coupled to a waveguide exhibits modified dissipation and quantum Zeno and anti-Zeno effects in the ultrastrong coupling regime, with the atom's size acting as a control parameter.

Contribution

It introduces a model of a superconducting giant atom in ultrastrong coupling and analyzes its dissipation and quantum Zeno effects, highlighting the atom size as a control mechanism.

Findings

Lamb shift modifies dissipation in the ultrastrong coupling regime.

Quantum Zeno and anti-Zeno effects depend on measurement intervals.

Giant atom size influences the occurrence of anti-Zeno effect.

Abstract

The giant atom system is a new paradigm in quantum optics, in which the traditional dipole approximation is not available. In this paper, we construct an artificial giant atom model by coupling a superconducting circuits to a transmission line by two coupling points. In the ultrastrong coupling regime, we show that the Lamb shift of the giant atom, which is induced by the non-negligible counter-rotating atom-waveguide coupling term, will modify its dissipation process. Furthermore, we investigate quantum Zeno and anti-Zeno effect where the size of the giant atom serves as a sensitive controller. Specifically, by comparing the critical measurement interval and the life time of the giant atom, we clarify the condition for the occurring of quantum anti-Zeno effect. We hope our work is useful for the application of giant atom system in the investigation of fundamental problems of quantum mechanics.