Measurement of Aharonov-Bohm oscillations in mesoscopic metallic rings in the presence of high-frequency electromagnetic fields
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 tauphi(P) agrees well with the anticipated power law tauphi proportional to P(-1/5) when the field-induced decoherence rate tauac(-1) is large compared to the intrinsic decoherence rate tauo(-1), measured in the absence of external fields. As theoretically expected, we observe a decline in field-induced decoherence when tauac(-1)<=tauo(-1). The frequency dependence of tauphi 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.