Scheme for a linear-optical controlled-phase gate with programmable phase shift

TL;DR

This paper introduces a linear-optical controlled-phase gate with a programmable phase shift controlled by a qubit, allowing dynamic tuning of the phase from 0 to pi, and discusses its experimental feasibility and success probability improvements.

Contribution

It presents a novel programmable controlled-phase gate using linear optics, where the phase is determined by a program qubit, unlike previous fixed-phase implementations.

Findings

Feasible with current linear-optical technology.

Phase shift tunable from 0 to pi via program qubit.

Success probability can be increased up to 1/12.

Abstract

We present a linear-optical scheme for a controlled-phase gate with tunable phase shift programmed by a qubit state. In contrast to all previous tunable controlled-phase gates, the phase shift is not hard-coded into the optical setup, but can be tuned to any value from 0 to pi by the state of a so-called program qubit. Our setup is feasible with current level of technology using only linear-optical components. We provide an experimental feasibility study to assess the gate's implementability. We also discuss options for increasing the success probability up to 1/12 which approaches the success probability of a optimal non-programmable tunable controlled-phase gate.