Excess noise in Al x Ga 1 - X As/GaAs based quantum rings

Riha, C. and Buchholz, S.S. and Chiatti, O. and Wieck, A.D. and Reuter, D. and Fischer, S.F.

Volume: 117 Pages:
DOI: 10.1063/5.0002247
Published: 2020

Cross-correlated noise measurements are performed in etched Al x Ga 1 - xAs/GaAs based quantum rings in equilibrium at a bath temperature of T bath = 4.2 K. The measured white noise exceeds the thermal (Johnson-Nyquist) noise expected from the measured electron temperature T e and the electrical resistance R. This excess part of the white noise decreases as T bath increases and vanishes for T bath ≥ 12 K. Excess noise is neither observed if one arm of a quantum ring is depleted of electrons nor in one-dimensional-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. © 2020 Author(s).

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