Photonic quantum walk with ultrafast time-bin encoding

TL;DR

This paper introduces a scalable photonic quantum walk platform using ultrafast time-bin encoding, enabling long-term phase stability and high fidelity over many steps without active stabilization.

Contribution

It presents a novel ultrafast time-bin encoding scheme for quantum walks that enhances scalability and phase stability in photonic systems.

Findings

Successfully implemented an 18-step quantum walk

Maintained phase stability over 50 hours

Achieved walk fidelity above 95%

Abstract

The quantum walk (QW) has proven to be a valuable testbed for fundamental inquiries in quantum technology applications such as quantum simulation and quantum search algorithms. Many benefits have been found by exploring implementations of QWs in various physical systems, including photonic platforms. Here, we propose a novel platform to perform quantum walks using an ultrafast time-bin encoding (UTBE) scheme. This platform supports the scalability of quantum walks to a large number of steps while retaining a significant degree of programmability. More importantly, ultrafast time bins are encoded at the picosecond time scale, far away from mechanical fluctuations. This enables the scalability of our platform to many modes while preserving excellent interferometric phase stability over extremely long periods of time without requiring active phase stabilization. Our 18-step QW is shown to preserve interferometric phase stability over a period of 50 hours, with an overall walk fidelity maintained above $95\%$