# Attractors and asymptotic dynamics of open discrete-time quantum walks on cycles

## TL;DR

This paper investigates a specific open quantum walk on cycles, revealing that its asymptotic behavior can be non-classical, including entanglement and oscillatory dynamics, depending on the system's parameters.

## Contribution

It introduces a simple open quantum walk model with non-classical asymptotic behaviors, including entanglement and oscillations, driven by a single position-dependent phase shift.

## Key findings

- Asymptotic states can be entangled between position and coin.
- The system exhibits classical and non-classical asymptotic behaviors.
- Oscillatory asymptotic motion can occur in the quantum walk.

## Abstract

Open quantum walks often lead to a classical asymptotic behavior. Here, we look for a simple open quantum walk whose asymptotic behavior can be non-classical. We consider a discrete-time quantum walk on n-cycle subject to a random coin-dependent phase shift at a single position. This finite system, whose evolution is described by only two Kraus operators, can exhibit all kinds of asymptotic behavior observable in quantum Markov chains: it either evolves towards a maximally mixed state, or partially mixed state, or tends to an oscillatory motion on an asymptotic orbit. We find that the asymptotic orbits do not have a product structure, therefore the corresponding states can manifest entanglement between the position and the coin degrees of freedom, even if the system started in a product state.