Fidelity decay for local perturbations: microwave evidence for oscillating decay exponents

TL;DR

This paper experimentally investigates fidelity decay in chaotic microwave billiards with local boundary perturbations, revealing oscillating decay rates that match theoretical predictions and demonstrate a transition between decay regimes.

Contribution

It provides the first experimental verification of oscillating decay exponents in fidelity decay due to local boundary perturbations in chaotic systems.

Findings

Observed non-monotonic crossover from Fermi Golden Rule to escape-rate decay regimes.

Detected pronounced oscillations of decay rate as a function of piston position.

Quantitatively confirmed theoretical semiclassical predictions.

Abstract

We study fidelity decay in classically chaotic microwave billiards for a local, piston-like boundary perturbation. We experimentally verify a predicted non-monotonic cross-over from the Fermi Golden Rule to the escape-rate regime of the Loschmidt echo decay with increasing local boundary perturbation. In particular, we observe pronounced oscillations of the decay rate as a function of the piston position which quantitatively agree with corresponding theoretical results based on a refined semiclassical approach for local boundary perturbations.