Experimental realization of a momentum-space quantum walk

TL;DR

This paper demonstrates a controlled discrete-time quantum walk using ultra-cold atoms' momentum states, exploring parameter effects and potential applications in atom interferometry.

Contribution

First experimental realization of a momentum-space quantum walk with detailed analysis of parameter effects and potential applications.

Findings

Controlled quantum walk dynamics achieved

Effects of parameters like noise and initial state studied

Potential for applications in atom interferometry

Abstract

We report on a discrete-time quantum walk that uses the momentum of ultra-cold rubidium-87 atoms as the walk space and two internal atomic states as the coin degree of freedom. Each step of the walk consists of a coin toss (a microwave pulse) followed by a unitary shift operator (a resonant ratchet pulse). We carry out a comprehensive experimental study on the effects of various parameters, including the strength of the shift operation, coin parameters, noise, and initialization of the system on the behavior of the walk. The walk dynamics can be well controlled in our experiment; potential applications include atom interferometry and engineering asymmetric walks.