A cold-atom ratchet interpolating between classical and quantum dynamics

TL;DR

This paper investigates the transition from classical to quantum behavior in a Bose-Einstein condensate subjected to a periodic potential, revealing a universal scaling law for the ratchet current across regimes.

Contribution

It introduces a unified framework describing the crossover between classical and quantum ratchet dynamics using a single scaling law.

Findings

Ratchet current can be similar in classical and quantum regimes under certain conditions.

A universal scaling law describes the ratchet behavior across the classical-quantum transition.

Experimental parameters can be combined into a single variable to predict the ratchet current.

Abstract

We study the crossover between classical and quantum dynamics by observing the behavior of a quantum ratchet created by exposing a Bose-Einstein condensate to short pulses of a potential which is periodic in both space and time. Such a ratchet is manifested by a directed current of particles, even though there is an absence of a net bias force. We confirm that the ratchet behavior can under certain circumstances be the same in both regimes. We demonstrate that this behavior can be understood using a single variable containing many of the experimental parameters and thus the ratchet current is describable using a single universal scaling law.