Cavity Nonlinear Optics at Low Photon Numbers from Collective Atomic Motion

TL;DR

This paper demonstrates Kerr nonlinearity and optical bistability at extremely low photon numbers using collective atomic motion in a cavity, enabling nonlinear optics with ultracold atoms and minimal photon interaction.

Contribution

It introduces a method to achieve strong nonlinear optical effects at low photon numbers via collective atomic motion in a cavity, a novel approach in quantum optics.

Findings

Optical bistability observed at photon numbers below one.

Collective atomic motion induces significant Kerr nonlinearity.

Longevity of atomic coherence enables low-photon nonlinear optics.

Abstract

We report on Kerr nonlinearity and dispersive optical bistability of a Fabry-Perot optical resonator due to the displacement of ultracold atoms trapped within. In the driven resonator, such collective motion is induced by optical forces acting upon up to $10^5$ $^{87}$Rb atoms prepared in the lowest band of a one-dimensional intracavity optical lattice. The longevity of atomic motional coherence allows for strongly nonlinear optics at extremely low cavity photon numbers, as demonstrated by the observation of both branches of optical bistability at photon numbers below unity.