Uniform cross phase modulation for nonclassical radiation pulses

TL;DR

This paper introduces a scheme for achieving uniform cross phase modulation between two nonclassical light pulses, enabling quantum non-demolition measurements and controlled phase gates, with analysis of ideal and non-ideal conditions.

Contribution

It presents a novel scheme for uniform XPM in nonclassical pulses and analyzes its potential for quantum information applications, including the effects of decoherence.

Findings

Uniform XPM can be achieved under ideal conditions.

Decoherence significantly impacts the scheme's performance.

Theoretical foundation for quantum non-demolition measurements and gates.

Abstract

We propose a scheme to achieve a uniform cross phase modulation (XPM) for two nonclassical light pulses and study its application for quantum non-demolition measurements of the photon number in a pulse and for controlled phase gates in quantum information. We analyze the scheme by quantizing a common phenomenological model for classical XPM. Our analysis first treats the ideal case of equal cross-phase modulation and pure unitary dynamics. This establishes the groundwork for more complicated studies of non-unitary dynamics and difference in phase shifts between the two pulses where decohering effects severely affect the performance of the scheme.