Few-Photon All-Optical {\pi} Phase modulation Based on a Double-{\Lambda} System

TL;DR

This paper introduces a novel all-optical phase modulation scheme using a double-{ extLambda} system in cold rubidium atoms, achieving a { extpi} phase shift with few-photon pulses, advancing quantum information processing.

Contribution

It presents a new phase-dependent mechanism in a double-{ extLambda} system enabling strong photon-photon interactions, distinct from traditional intensity-based methods.

Findings

Achieved a { extpi} phase shift with few-photon pulses.

Demonstrated control of the medium's properties via laser phase adjustments.

Proposed a potential route for quantum information applications.

Abstract

We propose an efficient all-optical phase modulation based on a double-{\Lambda} system and demonstrate a {\pi} phase shift of a few-photon pulse induced by another few-photon pulse in cold rubidium atoms with this scheme. By changing the phases of the applied laser fields, one can control the property of the double-{\Lambda} medium. This phase-dependent mechanism makes the double-{\Lambda} system different form the conventional cross-Kerr-based system which only depends on the applied laser intensities. The proposed scheme provides a new route to generate strong nonlinear interactions between photons, and may have potential for applications in quantum information technologies.