Universal multiport interferometers for post-selected multi-photon gates

TL;DR

This paper introduces a universal multiport interferometer approach to implement post-selected multi-photon quantum gates like Controlled-Z and Toffoli, enhancing success probabilities and expanding the capabilities of existing interferometric schemes.

Contribution

It presents a novel method using multiport interferometers, auxiliary paths, and post-selection to realize high-probability multi-photon quantum gates, extending the applications of Reck and Clements schemes.

Findings

Achieved higher success probabilities for multi-photon gates

Demonstrated equivalence to standard quantum gates like CNOT and Toffoli

Extended the applicability of interferometric schemes beyond Boson Sampling

Abstract

We show how to use universal multiport interferometers' schemes in order to create photonic post-selected Controlled-Z and Controlled-Controlled-Z gates, which are equivalent, modulo single-qubit gates, to Controlled-NOT and Toffoli gates, respectively. The new proposed method is based on the following ingredients: identical single photons, Mach-Zehnder interferometer networks, single-photon detectors and post-selection. In particular, by using dual-rail path encoding together with auxiliary paths and single photons, we improve the success probabilities of such gates. This result further proves the complexity and richness of Reck and Clements schemes beyond the usual notions and practices of Boson Sampling.