A high-speed tunable beam splitter for feed-forward photonic quantum information processing

TL;DR

This paper presents a high-speed, tunable, polarization-independent beam splitter for photonic quantum information processing, enabling rapid feed-forward quantum gates with high interference contrast.

Contribution

It introduces a novel electro-optically controlled beam splitter with fast switching and tunability for path qubits, advancing photonic quantum computing capabilities.

Findings

Interference contrast above 95% with heralded single photons

Switching time of approximately 5.6 ns

Maximum repetition rate of 2.5 MHz

Abstract

We realize quantum gates for path qubits with a high-speed, polarization-independent and tunable beam splitter. Two electro-optical modulators act in a Mach-Zehnder interferometer as high-speed phase shifters and rapidly tune its splitting ratio. We test its performance with heralded single photons, observing a polarization-independent interference contrast above 95%. The switching time is about 5.6 ns, and a maximal repetition rate is 2.5 MHz. We demonstrate tunable feed-forward operations of a single-qubit gate of path-encoded qubits and a two-qubit gate via measurement-induced interaction between two photons.