On the physical realizability of quantum stochastic walks

TL;DR

This paper examines the physical limitations of implementing quantum stochastic walks, highlighting the challenges in realizing their open system evolutions due to complex requirements like reservoir engineering.

Contribution

It analyzes the constraints on physical realizability of quantum stochastic walks and discusses the assumptions and difficulties involved in experimental implementations.

Findings

General implementations require solving complex unitary dynamics.

Experimental realization demands sophisticated reservoir engineering.

Constraints limit practical applications of quantum stochastic walks.

Abstract

Quantum walks are a promising framework that can be used to both understand and implement quantum information processing tasks. The quantum stochastic walk is a recently developed framework that combines the concept of a quantum walk with that of a classical random walk, through open system evolution of a quantum system. Quantum stochastic walks have been shown to have applications in as far reaching fields as artificial intelligence. However, there are significant constraints on the kind of open system evolutions that can be realized in a physical experiment. In this work, we discuss the restrictions on the allowed open system evolution, and the physical assumptions underpinning them. We show that general implementations would require the complete solution of the underlying unitary dynamics, and sophisticated reservoir engineering, thus weakening the benefits of experimental investigations.