Dresden 2011 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 10: Posters I
DY 10.13: Poster
Montag, 14. März 2011, 17:00–19:00, P4
Pseudo-Rabi oscillations in dielectric absorption measurements on the glass BK7 at low temperatures — •Gudrun Fickenscher, Manfred von Schickfus, Andreas Fleischmann, and Christian Enss — Kirchhoff-Institut für Physik, Heidelberg University, Germany
The low temperature properties of glasses are to a large extent well described by the phenomenological standard tunnelling model. However, the behaviour of the dielectric function and the decay of the polarisation echo amplitude at temperatures below 50mK are not fully explained. To gain better understanding of the microscopic structure of tunnelling systems and the relaxation mechanisms in glasses, dielectric measurements at temperatures down to a few mK were performed with a Niobium microstrip λ/2 resonator (fres ≈ 1GHz) structured onto a plate of BK7. We observe the saturation of the dielectric absorption due to resonant tunnelling systems. During the saturation process, we observe surprising low frequency oscillations (f ≈ 10kHz) of the resonator transmission whose frequency is proportional to the electric field amplitude as would be expected for Rabi oscillations. They are clearly visible at temperatures from 10 to more than 500mK. However, we would not expect a coherent effect in glasses in this temperature and frequency range since it is known from earlier experiments that the phase relaxation time is below 1 µs at temperatures above 100mK. Experimental data of this phenomenon, which has never been observed in a glass before, will be shown and discussed.