Experimental Realization of a Quantum Ratchet Through Phase Modulation

TL;DR

This paper demonstrates an experimental quantum ratchet using phase modulation in a delta-kicked rotor system with ultracold atoms, showing directed transport without an external bias, and connects observations to -classical theory.

Contribution

It presents the first experimental realization of a quantum ratchet via phase modulation in a delta-kicked rotor with Bose-Einstein condensates, highlighting directed transport in a chaotic phase space.

Findings

Observation of unidirectional momentum current

Controlled quantum ratchet behavior without external bias

Validation of -classical theory in quantum transport

Abstract

We report on an experimental realization of unidirectional transporting island structures in an otherwise chaotic phase space of the delta-kicked rotor system. Using a Bose-Einstein Condensate as a source of ultracold atoms, we employ asymmetric phase modulation in the kicks, with the narrow momentum distribution of the atoms allowing us to address individual island structures. We observe quantum ratchet behavior in this system, with clear directed momentum current in the absence of a directional force, which we characterize and connect to \epsilon-classical theory.