Giant-atom-enabled quantum optics with valley-polarized photons

TL;DR

This paper demonstrates how giant atoms coupled to engineered honeycomb resonator lattices can selectively emit valley-polarized photons, enabling robust chiral quantum optics without breaking time-reversal symmetry.

Contribution

It introduces a method to control valley-polarized photon emission using nonlocal coupling of a two-level emitter to a honeycomb lattice, advancing valleytronics in quantum optics.

Findings

Giant atoms can be tailored to emit into specific valleys.

Valley-polarized emission can be achieved at domain walls.

Chiral emission occurs without breaking time-reversal symmetry.

Abstract

Valleytronics and valley photonics exploit the valley degree of freedom to encode and manipulate information. Here we show that photonic valleys can be selectively addressed in quantum optics using a simple two-level emitter, provided it is coupled nonlocally to the field, thereby realizing a so-called giant atom. Specifically, we consider a qubit coupled at multiple points to an engineered honeycomb lattice of resonators with detuned sublattice frequencies. By tailoring the geometry of the coupling points, the giant atom can be made to emit selectively into a single valley. The emitted photons thereby acquire a well-defined valley character and inherit the associated Berry curvature. By placing the qubit near a domain wall between regions of opposite sublattice detuning, whose interface supports valley-polarized edge modes, emission becomes chiral along the domain wall. This provides a promising route toward implementation of single-photon disorder-robust chiral emission without breaking time-reversal symmetry of the electromagnetic medium in platforms such as circuit QED.