Single-photon interference due to motion in an atomic collective excitation

TL;DR

This paper demonstrates a novel interference effect in atomic collective excitations, showing how atomic motion causes quantum beats in heralded single photons, with potential applications in quantum communication.

Contribution

It introduces a new interference phenomenon caused by atomic motion in collective excitations and demonstrates control over this effect using laser dressing and magnetic fields.

Findings

Observation of collective quantum beats in photon arrival times

Control of interference via laser and magnetic fields

Potential extension to telecom wavelengths

Abstract

We experimentally demonstrate the generation of heralded bi-chromatic single photons from an atomic collective spin excitation (CSE). The photon arrival times display collective quantum beats, a novel interference effect resulting from the relative motion of atoms in the CSE. A combination of velocity-selective excitation with strong laser dressing and the addition of a magnetic field allows for exquisite control of this collective beat phenomenon. The present experiment uses a diamond scheme with near-IR photons that can be extended to include telecommunications-wavelengths or modified to allow storage and retrieval in an inverted-Y scheme.