Experimental quantum-walk revival with a time-dependent coin

TL;DR

This paper experimentally demonstrates a quantum walk with a time-dependent coin bias, showing two periodic revivals of the walker distribution using a single-photon setup with a linearly ramped coin flip.

Contribution

It introduces a novel experimental method for implementing a time-dependent coin in a quantum walk, enabling observation of periodic revivals in the walker distribution.

Findings

Demonstrated two periodic revivals of the quantum walk distribution.

Implemented a linearly ramped coin bias in a single-photon quantum walk.

Validated the effect of time-dependent coin bias on quantum walk dynamics.

Abstract

We demonstrate a quantum walk with time-dependent coin bias. With this technique we realize an experimental single-photon one-dimensional quantum walk with a linearly-ramped time-dependent coin flip operation and thereby demonstrate two periodic revivals of the walker distribution. In our beam-displacer interferometer, the walk corresponds to movement between discretely separated transverse modes of the field serving as lattice sites, and the time-dependent coin flip is effected by implementing a different angle between the optical axis of half-wave plate and the light propagation at each step. Each of the quantum-walk steps required to realize a revival comprises two sequential orthogonal coin-flip operators, with one coin having constant bias and the other coin having a time-dependent ramped coin bias, followed by a conditional translation of the walker.