Observation of coherence revival and fidelity saturation in a delta-kicked rotor potential

TL;DR

This paper experimentally demonstrates that in a delta-kicked rotor system, matter-wave coherence can revive and saturate at a non-zero level under quantum resonance conditions, revealing a fundamental limit to fidelity decay.

Contribution

It provides the first experimental observation of coherence revival and saturation in a delta-kicked rotor potential, linking quantum resonance to fidelity saturation in atom interferometry.

Findings

Coherence revival occurs at quantum resonance conditions.

Coherence saturates at a non-zero level despite increasing kicks.

Invariant matter-wave coherence distribution under kicked rotor perturbations.

Abstract

We experimentally investigate the effect of atomic $\delta$-kicked rotor potentials on the mutual coherence between wavepackets in an atom interferometer. The differential action of the kicked rotor degrades the mutual coherence, leading to a reduction of the interferometry fringe visibility; however, when the repetition rate of the kicked rotor is at or near the quantum resonance, we observe revival of matter-wave coherence as the number of kicks increases, resulting in non-vanishing coherence in the large kick number limit. This coherence saturation effect reflects a saturation of fidelity decay due to momentum displacements in deep quantum regime. The saturation effect is accompanied with an invariant distribution of matter-wave coherence under the kicked rotor perturbations.