Reliability of optical gate array for C-Sign operator

TL;DR

This paper evaluates the reliability of an optical gate array for the C-Sign operator in quantum computing, considering realistic decoherence effects like photon leak and atom-mediated leakage, and assesses how these factors limit quantum computation.

Contribution

It introduces a realistic model of decoherence in optical gate arrays for the C-Sign operator using the JC model with Lindblad equation.

Findings

Photon leak impacts the validity of the C-Sign operator.

Limitations on quantum computation imposed by decoherence factors.

Quantitative estimates of decoherence effects on gate fidelity.

Abstract

We study optical gate array of KLM model of quantum computer for C-Sign operator, which contains linear elements and two nonlinear phase shifts. Linear elements and photon counting are taken to be ideal, whereas nonlinear phase shifts are subject of realistic and unavoidable factors of decoherence: the immediate photon leak from cavities and mediated leakage with the atom, which flies out of the cavity and plays the role of ancilla. We use JC model with Lindblad master equation to estimate the dependence of the validity of C-Sign operator from the rate of photon leak and estimate the limitation, which this validity imposes to quantum computations.