Collective Enhancement of Photon Blockade via Two-Photon Interactions

TL;DR

This paper demonstrates that collective two-photon interactions in a quantum resonator can enhance photon blockade effects, enabling generation of non-classical light states even without strong individual atom-light coupling.

Contribution

It introduces a novel approach showing collective two-photon couplings can enhance photon blockade, contrasting with traditional methods requiring strong single-atom coupling.

Findings

Collective two-photon interactions improve photon blockade.

Suppressed higher-order correlations with increasing atom number.

Unitary transmission constrained only by decoherence.

Abstract

Analogous to Coulomb blockade for electrons, photon blockade is a key quantum optical effect in which the presence of one photon prevents the transmission of subsequent ones through a nonlinear medium. Beyond its fundamental interest, photon and multi-photon blockade are actively studied as mechanisms for generating technologically-relevant quantum states of light. Although photon blockade typically requires achieving strong light-matter coupling, increasing the number of atoms fails to enhance antibunching. Here, we analyze the optical transmission properties of a quantum resonator that embeds a two-photon-coupled ensemble of emitters, combining an approximate analytical approach with full quantum numerical simulations. We show that when light and matter are coupled via a two-photon interaction, both single- and multi-photon blockade can benefit from a collective enhancement. We propose different driving schemes in which the second or third-order correlation functions are strongly suppressed with increasing atom number. Differently from established methods, this collective enhancement of non-classical properties occurs with unitary transmission and is ultimately constrained only by decoherence. This demonstrates that collective two-photon couplings are a powerful mechanism for realizing photon blockade even in platforms where individual strong coupling is not achievable.