Maximal coin-walker entanglement in a ballistic quantum walk

TL;DR

This paper demonstrates how position-inhomogeneous quantum walks can generate maximal high-dimensional entanglement efficiently, using a stable optical network, advancing quantum information processing capabilities.

Contribution

It introduces a method to produce maximal coin-walker entanglement in quantum walks using a stable optical setup with phase control, enhancing entanglement engineering.

Findings

Maximal entanglement achieved at odd steps or asymptotically at even steps.

Quadratic speedup in wave-function spread maintained.

Implementation via a polarization Sagnac loop in a time-bin optical network.

Abstract

We report the position-inhomogeneous quantum walk (IQW) can be utilized to produce the maximal high dimensional entanglement while maintaining the quadratic speedup spread of the wave-function. Our calculations show that the maximal coin-walker entanglement can be generated in any odd steps or asymptotically in even steps, and the nearly maximal entanglement can be obtained in even steps after $2$. We implement the IQW by a stable resource-saving time-bin optical network, in which a polarization Sagnac loop is employed to realize the precisely tunable phase shift. Our approach opens up an efficient way for high-dimensional entanglement engineering as well as promotes investigations on the role of coin-walker interactions in QW based applications.