Qubit-photon corner states in all dimensions

TL;DR

This paper demonstrates that a single quantum emitter can trap light in any dimension by engineering photonic environments, enabling robust qubit-photon corner states through destructive interference.

Contribution

It introduces a method to achieve photon trapping in all dimensions using tailored photonic baths with open boundaries, expanding the understanding of light confinement.

Findings

Single emitter can trap light in all dimensions.

Corner states are robust under parameter fluctuations.

States persist in ultrastrong coupling regime.

Abstract

A single quantum emitter coupled to a one-dimensional photon field can perfectly trap a photon when placed close to a mirror. This occurs when the interference between the emitted and reflected light is completely destructive, leading to photon confinement between the emitter and the mirror. In higher dimensions, the spread of the light field in all directions hinders interference and, consequently, photon trapping by a single emitter is considered to be impossible. In this work, we show that is not the case by proving that a single emitter can indeed trap light in any dimension. We provide a constructive recipe based on judiciously coupling an emitter to a photonic crystal-like bath with properly designed open boundary conditions. The directional propagation of the photons in such baths enables perfect destructive interference, forming what we denote as \emph{qubit-photon corner states}. We characterize these states in all dimensions, showing that they are robust under fluctuations of the emitter's properties, and persist also in the ultrastrong coupling regime.