Single photon nonlinearities using arrays of cold polar molecules

TL;DR

This paper models single photon nonlinearities in cold polar molecules using dipole-dipole interactions and dark state polaritons, aiming for applications in optical quantum computing.

Contribution

It introduces a framework for controlling photon nonlinearities via dark state polaritons in cold polar molecules, highlighting potential for quantum information processing.

Findings

Photons acquire a measurable nonlinear phase at the single photon level.

A manifold of symmetric eigenstates provides a basis for the nonlinearity.

Decoherence mainly from non-symmetric interactions and phonon dispersion.

Abstract

We model single photon nonlinearities resulting from the dipole-dipole interactions of cold polar molecules. We propose utilizing ``dark state polaritons'' to effectively couple photon and molecular states; through this framework, coherent control of the nonlinearity can be expressed and potentially used in an optical quantum computation architecture. Due to the dipole-dipole interaction the photons pick up a measurable nonlinear phase even in the single photon regime. A manifold of protected symmetric eigenstates is used as basis. Depending on the implementation, major sources of decoherence result from non-symmetric interactions and phonon dispersion. We discuss the strength of the nonlinearity per photon and the feasibility of this system.