Large Cross-phase Modulation Based on Double EIT in a Four-level Tripod Atomic System

TL;DR

This paper demonstrates large cross-phase modulation using double EIT in a four-level tripod system with 87Rb atoms, achieving significant XPM coefficients and high transmission, relevant for quantum information processing.

Contribution

It experimentally shows large cross-phase modulation and double EIT effects in a four-level tripod atomic system, advancing quantum nonlinear optics applications.

Findings

XPM coefficients larger than 2×10^-5 cm^2/W

Transmission higher than 60% at slight detuning

Simultaneous EIT effects for probe and trigger fields

Abstract

We report the experimental observations on the simultaneous EIT effects for probe and trigger fields (double EIT) as well as the large cross-phase modulation (XPM) between the two fields in a four-level tripod EIT system of the D1 line of 87Rb atoms. The XPM coefficients (larger than 2*10-5cm2/W) and the accompanying transmissions (higher than 60%) are measured at slightly detuning of the probe field from the exact EIT resonance condition. The presented system can be applied in the recently proposed quantum information processing with weak cross-Kerr nonlinearities.