Two-Photon Beatings Using Biphotons Generated from a Two-Level System

TL;DR

This paper proposes a two-photon beating experiment using biphotons from a two-level system, demonstrating tunable interference visibility and potential Bell inequality violation, while also probing the quantum detection process.

Contribution

It introduces a novel experimental setup for biphoton interference from a two-level system, enabling control over visibility and exploring quantum detection effects.

Findings

Visibility can be tuned from 0% to 100% by adjusting experimental parameters.

The experiment indicates potential violation of Bell-type inequalities.

Interference disappears when Mollow peak separation matches photon absorption timescales.

Abstract

We propose a two-photon beating experiment based upon biphotons generated from a resonant pumping two-level system operating in a backward geometry. On the one hand, the linear optical-response leads biphotons produced from two sidebands in the Mollow triplet to propagate with tunable refractive indices, while the central-component propagates with unity refractive index. The relative phase difference due to different refractive indices is analogous to the pathway-length difference between long-long and short-short in the original Franson interferometer. By subtracting the linear Rayleigh scattering of the pump, the visibility in the center part of the two-photon beating interference can be ideally manipulated among [0, 100%] by varying the pump power, the material length, and the atomic density, which indicates a Bell-type inequality violation. On the other hand, the proposed experiment may be an interesting way of probing the quantum nature of the detection process. The interference will disappear when the separation of the Mollow peaks approaches the fundamental timescales for photon absorption in the detector.