Regensburg 2019 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 25: Disordered Quantum Systems

TT 25.5: Vortrag

Dienstag, 2. April 2019, 10:30–10:45, H23

Microstructured Superconducting Resonator Technique for Measurements of Dielectric Polarization Echoes at Very Short Pulse Separation Times — •Andreas Schaller, Marcel Haas, Robert Haase, Anna Pollithy, Sergey Tsurkan, Matthias Sinnwell, Andreas Reiser, Andreas Fleischmann, and Christian Enss — Kirchhoff-Institute for Physics, Heidelberg University, D-69120 Heidelberg

The anomalous properties of amorphous solids at low temperatures are governed by tunneling systems, which are described as two-level systems in the phenomenological standard tunneling model. However, measurements of the dielectric constant, sound velocity, and dielectric polarization echoes of glasses containing atoms carrying large nuclear quadrupole moments revealed unexpected characteristics, such as magnetic field dependencies, which are not observed in glasses without nuclear quadrupole moments.

We present results of dielectric two-pulse polarization echo measurements carried out on different multicomponent glasses and polymers containing large nuclear quadrupole moments. For all these samples the two-pulse-echo decay occurs on a comparably short timescale. In order to investigate those echo decays on sub-µs times we developed planar microfabricated superconducting resonators. We were able to measure dielectric polarization echoes at unprecedentedly small pulse separation times and could see the flattening off of the polarization amplitude of N-BK7 towards small pulse separation times, as predicted by spectral diffusion theory.