Lecture notes on Optical Quantum Computing

TL;DR

This paper discusses the potential of optical systems, especially photons, for quantum computing, reviewing proposals and focusing on photonic qubits as a promising approach in the field.

Contribution

It provides an overview of optical quantum computing, emphasizing photonic qubits and summarizing key proposals and challenges in using light for quantum information processing.

Findings

Photons are promising carriers for quantum information.

Optical quantum computing faces significant control challenges.

Several proposals exist for implementing photonic qubits.

Abstract

A quantum computer is a machine that can perform certain calculations much faster than a classical computer by using the laws of quantum mechanics. Quantum computers do not exist yet, because it is extremely difficult to control quantum mechanical systems to the necessary degree. What is more, we do at this moment not know which physical system is the best suited for making a quantum computer (although we have some ideas). It is likely that a mature quantum information processing technology will use (among others) light, because photons are ideal carriers for quantum information. These notes are an expanded version of the five lectures I gave on the possibility of making a quantum computer using light, at the Summer School in Theoretical Physics in Durban, 14-24 January, 2007. There are quite a few proposals using light for quantum computing, and I can highlight only a few here. I will focus on photonic qubits, and leave out continuous variables completely. I assume that the reader is familiar with basic quantum mechanics and introductory quantum computing.