Controlled-phase gate for photons based on stationary light

TL;DR

This paper proposes a method to implement a controlled-phase gate for photons using stationary light in an atomic ensemble, enhancing photon interactions regardless of single-atom coupling strength.

Contribution

It introduces a novel approach leveraging stationary light to achieve strong photon-photon interactions for quantum gates, scalable with atom number.

Findings

Analytical fidelity expressions for deterministic and heralded gate modes

Interaction strength scales with total atom number, independent of single-atom coupling

Potential for practical photon-based quantum logic gates

Abstract

We propose a method to induce strong effective interactions between photons mediated by an atomic ensemble. To achieve this, we use the so-called stationary light effect to enhance the interaction. Regardless of the single-atom coupling to light, the interaction strength between the photons can be enhanced by increasing the total number of atoms. For sufficiently many atoms, the setup can be viable as a controlled-phase gate for photons. We derive analytical expressions for the fidelities for two modes of gate operation: deterministic and heralded conditioned on the presence of two photons at the output.