Noise reduction by bias cooling in gated Si/SixGe1-x quantum dots

Julian Ferrero; Thomas Koch; Sonja Vogel; Daniel Schroller; Viktor Adam; Ran Xue; Inga Seidler; Lars R. Schreiber; Hendrik Bluhm; Wolfgang Wernsdorfer

arXiv · 2405.00238

Noise reduction by bias cooling in gated Si/SixGe1-x quantum dots

Julian Ferrero·Thomas Koch·Sonja Vogel·Daniel Schroller·Viktor Adam·Ran Xue·Inga Seidler·Lars R. Schreiber·Hendrik Bluhm·Wolfgang Wernsdorfer

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Abstract

Silicon-Germanium heterostructures are a promising quantum circuit platform, but crucial aspects as the long-term charge dynamics and cooldown-to-cooldown variations are still widely unexplored quantitatively. In this letter we present the results of an extensive bias cooling study performed on gated silicon-germanium quantum dots with an Al2O3-dielectric. Over 80 cooldowns were performed in the course of our investigations. The performance of the devices is assessed by low-frequency charge noise measurements in the band of 200 micro Hertz to 10 milli Hertz. We measure the total noise power as a function of the applied voltage during cooldown in four different devices and find a minimum in noise at 0.7V bias cooling voltage for all observed samples. We manage to decrease the total noise power median by a factor of 6 and compute a reduced tunneling current density using Schr\"odinger-Poisson simulations. Furthermore, we show the variation in noise from the same device in the course of eleven different cooldowns performed under the nominally same conditions.

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Julian Ferrero, Thomas Koch, Sonja Vogel, Daniel Schroller, Viktor Adam, Ran Xue, Inga Seidler, Lars R. Schreiber, Hendrik Bluhm, Wolfgang Wernsdorfer. 2024-04-30. Noise reduction by bias cooling in gated Si/SixGe1-x quantum dots. https://arxiv.org/abs/2405.00238

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