Highly Entangled Photons and Rapidly Responding Polarization Qubit Phase Gates in a Room-Temperature Active Raman Gain Medium

TL;DR

This paper proposes a room-temperature atomic system for generating entangled photons and fast polarization qubit phase gates, leveraging active Raman gain to overcome absorption and Doppler effects.

Contribution

It introduces a novel four-state tripod atomic system with active Raman gain for entanglement and quantum gates, distinct from electromagnetically induced transparency methods.

Findings

Highly entangled photon pairs can be produced.

Rapidly responding polarization qubit phase gates are feasible.

Enhanced cross-phase modulation enables fast quantum operations.

Abstract

We present a scheme for obtaining entangled photons and quantum phase gates in a room-temperature four-state tripod-type atomic system with two-mode active Raman gain (ARG). We analyze the linear and nonlinear optical response of this ARG system and show that the scheme is fundamentally different from those based on electromagnetically induced transparency and hence can avoid significant probe-field absorption as well as temperature-related Doppler effect. We demonstrate that highly entangled photon pairs can be produced and rapidly responding polarization qubit phase gates can be constructed based on the unique features of enhanced cross-phase modulation and superluminal probe-field propagation of the system.