Strongly interacting photons in one-dimensional continuum

TL;DR

This paper reviews recent experimental and theoretical advances in creating strong photon-photon interactions in one-dimensional systems, crucial for quantum optics and photonic quantum technologies.

Contribution

It provides a comprehensive overview of two experimental platforms for strongly interacting photons and compares theoretical models with experimental results.

Findings

Demonstration of strong photon-photon interactions in superconducting qubits and Rydberg atoms.

Summary of quantum optical effects enabled by these interactions.

Discussion of potential quantum devices utilizing strongly interacting photons.

Abstract

Photon-photon scattering in vacuum is extremely weak. However, strong effective interactions between single photons can be realized by employing strong light-matter coupling. These interactions are a fundamental building block for quantum optics, bringing many-body physics to the photonic world and providing important resources for quantum photonic devices and for optical metrology. In this Colloquium, we review the physics of strongly-interacting photons in one-dimensional systems with no optical confinement along the propagation direction. We focus on two recently-demonstrated experimental realizations: superconducting qubits coupled to open transmission lines, and interacting Rydberg atoms in a cold gas. Advancements in the theoretical understanding of these systems are presented in complementary formalisms and compared to experimental results. The experimental achievements are summarized alongside a description of the quantum optical effects and quantum devices emerging from them.