Ultra-bright biphoton emission from an atomic vapor based on Doppler-free four-wave-mixing and collective emission

TL;DR

This paper introduces a new atomic vapor scheme that enables ultra-bright, Doppler-free biphoton emission in all directions, achieving extremely high photon pair rates suitable for quantum applications.

Contribution

The authors propose a novel 'butterfly' level scheme combined with multi-photon Doppler-free pumping to enhance biphoton emission efficiency and directionality in atomic vapors.

Findings

Photon pair rate of ~10^12 per second

Emission occurs in all directions (4π solid angle)

Background Rayleigh scattering is suppressed

Abstract

We propose a novel `butterfly' level scheme to generate highly correlated photon pairs from atomic vapors. With multi-photon Doppler-free pumping, background Rayleigh scattering is dipole-forbidden and collective emission is permitted in all directions. This results in usable pairs generated simultaneously in the full $4\pi$ solid angle. Collecting these pairs can produce photon pairs at a rate of $\sim 10^{12}$ per second, given only moderate ensemble sizes of $\sim 10^6$ atoms.