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HL: Fachverband Halbleiterphysik
HL 49: Quantum dots and wires II
HL 49.7: Vortrag
Mittwoch, 18. März 2020, 17:00–17:15, POT 151
Excess noise in quantum ring interferometers — Christian Riha1, Sven S. Buchholz1, Olivio Chiatti1, Andreas D. Wieck2, Dirk Reuter3, and •Saskia F. Fischer1 — 1Novel Materials Group, Humboldt-Universität zu Berlin, 10099 Berlin, Germany — 2Angewandte Festkörperphysik, Ruhr-Universität Bochum, 44780 Bochum, Germany — 3Optoelektronische Materialien und Bauelemente, Universiät Paderborn, 33098 Paderborn
Cross-correlated noise measurements are performed in etched AlxGa1−xAs/GaAs based quantum rings in equilibrium at a bath temperature of Tbath=4.2 K. The measured white noise exceeds the thermal noise expected from the measured electron temperature Te and the electrical resistance R. This excess part of the white noise decreases as Tbath increases and vanishes for Tbath>12 K. Excess noise is not observed if one arm of a quantum ring is depleted of electrons or in 1D-constrictions that have a length and width comparable to the quantum rings. A model is presented that suggests that the excess noise originates from the correlation of noise sources, mediated by phase-coherent propagation of electrons.