Quantum optics with giant atoms -- the first five years

TL;DR

This paper surveys the emerging field of giant atoms in quantum optics, highlighting how multiple coupling points lead to unique interference effects and potential applications, contrasting with traditional point-like atom models.

Contribution

It provides a comprehensive overview of giant atom systems, including theoretical and experimental insights, and discusses their novel interference phenomena and applications.

Findings

Giant atoms exhibit interference effects not seen in small atoms.

Multiple coupling points enable new quantum control techniques.

Experimental realizations confirm theoretical predictions.

Abstract

In quantum optics, it is common to assume that atoms can be approximated as point-like compared to the wavelength of the light they interact with. However, recent advances in experiments with artificial atoms built from superconducting circuits have shown that this assumption can be violated. Instead, these artificial atoms can couple to an electromagnetic field at multiple points, which are spaced wavelength distances apart. In this chapter, we present a survey of such systems, which we call \textit{giant atoms}. The main novelty of giant atoms is that the multiple coupling points give rise to interference effects that are not present in quantum optics with ordinary, small atoms. We discuss both theoretical and experimental results for single and multiple giant atoms, and show how the interference effects can be used for interesting applications. We also give an outlook for this emerging field of quantum optics.