On photonic controlled phase gates

TL;DR

This paper analyzes the success probabilities of photonic controlled phase gates in linear optical quantum computing, identifying optimal success rates and proposing implementable network designs suitable for current integrated optical technologies.

Contribution

It determines the optimal success probabilities for controlled phase gates with one and two controls and designs feasible networks for their implementation using existing experimental capabilities.

Findings

Identified optimal success probabilities for controlled phase gates.

Constructed networks compatible with current integrated optical technology.

Provided detailed implementation schemes for practical realization.

Abstract

As primitives for entanglement generation, controlled phase gates take a central role in quantum computing. Especially in ideas realizing instances of quantum computation in linear optical gate arrays a closer look can be rewarding. In such architectures, all effective non-linearities are induced by measurements: Hence the probability of success is a crucial parameter of such quantum gates. In this note, we discuss this question for controlled phase gates that implement an arbitrary phase with one and two control qubits. Within the class of post-selected gates in dual-rail encoding with vacuum ancillas we identify the optimal success probabilities. We construct networks that allow for an implementation by means of todays experimental capabilities in detail. The methods employed here appear specifically useful with the advent of integrated linear optical circuits, providing stable interferometers on monolithic structures.