Measurement of Aharonov-Bohm oscillations in mesoscopic metallic rings in the presence of high-frequency electromagnetic fields

TL;DR

This study measures Aharonov-Bohm oscillations in metallic rings under high-frequency electromagnetic fields, revealing how decoherence time scales depend on power and frequency, and providing insights into intrinsic decoherence mechanisms.

Contribution

It experimentally demonstrates the power-law dependence of decoherence time on electromagnetic power and identifies a characteristic frequency where decoherence effects change, confirming theoretical predictions.

Findings

Decoherence time scales follow a P^(-1/5) power law with increasing power.

A minimum in oscillation amplitude occurs at frequency omega_(ac)=1/tau_(o).

Intrinsic decoherence time can be directly measured from oscillation suppression.

Abstract

We report measurements of Aharonov-Bohm oscillations in normal metal rings in the presence of high frequency electromagnetic fields. The power dependence of the decoherence time scale tau_phi(P) agrees well with the anticipated power law tau_phi proportional to P^(-1/5) when the field-induced decoherence rate tau_ac^(-1) is large compared to the intrinsic decoherence rate tau_o^(-1), measured in the absence of external fields. As theoretically expected, we observe a decline in field-induced decoherence when tau_ac^(-1)<=tau_o^(-1). The frequency dependence of tau_phi shows a minimum in the oscillation amplitude at a characteristic frequency, omega_(ac)=1/tau_(o), where tau_(o) is evaluated from the oscillation amplitude using the standard mesoscopic theory. Both the suppression in the oscillation amplitude and the concomitant change in conductivity allow a direct measurement of the intrinsic decoherence time scale.