Effects of Loss and Decoherence on a Simple Quantum Computer

TL;DR

This paper studies how loss and decoherence affect a simple optical quantum computer solving the Deutsch problem, analyzing error models and correction strategies to improve performance.

Contribution

It introduces models for loss and decoherence effects on optical quantum gates and evaluates error correction methods for a basic quantum computing setup.

Findings

Loss errors can be completely avoided with proper design.

Decoherence errors can be partially corrected using projective techniques.

The study provides insights into error mitigation for optical quantum computers.

Abstract

We investigate the impact of loss (amplitude damping) and decoherence (phase damping) on the performance of a simple quantum computer which solves the one-bit Deutsch problem. The components of this machine are beamsplitters and nonlinear optical Kerr cells, but errors primarily originate from the latter. We develop models to describe the effect of these errors on a quantum optical Fredkin gate. The results are used to analyze possible error correction strategies in a complete quantum computer. We find that errors due to loss can be avoided perfectly by appropriate design techniques, while decoherence can be partially dealt with using projective error correction.