Quantum to Classical Walk Transitions Tuned by Spontaneous Emissions

TL;DR

This paper demonstrates a controlled transition from quantum to classical walks in a cold atom system by tuning spontaneous emissions, revealing insights into decoherence effects on quantum dynamics.

Contribution

It introduces a method to control quantum walk robustness via external spontaneous emission tuning in cold atom experiments.

Findings

Quantum walks are stable for up to ten steps before transitioning to classical behavior.

Controlled spontaneous emissions can induce and study quantum to classical walk transitions.

The scheme can be applied to enhance understanding of decoherence in quantum systems.

Abstract

We have realized a quantum walk in momentum space with a rubidium spinor Bose-Einstein condensate by applying a periodic kicking potential as a walk operator and a resonant microwave pulse as a coin toss operator. The generated quantum walks appear to be stable for up to ten steps and then quickly transit to classical walks due to spontaneous emissions induced by laser beams of the walk operator. We investigate these quantum to classical walk transitions by introducing well controlled spontaneous emissions with an external light source during quantum walks. Our findings demonstrate a scheme to control the robustness of the quantum walks and can also be applied to other cold atom experiments involving spontaneous emissions.