Journal Article

FZJ-2020-05309

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Low-frequency spin qubit energy splitting noise in highly purified 28Si/SiGe

Struck, T. ; Hollmann, A. ; Schauer, F. ; Fedorets, O.Extern* ; Schmidbauer, A. ; Sawano, K. ; Riemann, H. ; Abrosimov, N. V. ; Cywiński, Ł.Extern* ; Bougeard, D. ; Schreiber, L. (Corresponding author)FZJ*

2020
Taylor & Francis816513 London

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Please use a persistent id in citations: http://hdl.handle.net/2128/26563  doi:10.1038/s41534-020-0276-2

Abstract: We identify the dominant source for low-frequency spin qubit splitting noise in a highly isotopically-purified silicon device with an embedded nanomagnet and a spin echo decay time Techo2 = 128 µs. The power spectral density (PSD) of the charge noise explains both, the clear transition from a 1/f2- to a 1/f-dependence of the splitting noise PSD as well as the experimental observation of a decreasing time-ensemble spin dephasing time, from T∗2≈ 20 µs, with increasing measurement time over several hours. Despite their strong hyperfine contact interaction, the few 73Ge nuclei overlapping with the quantum dot in the barrier do not limit T∗2, likely because their dynamics is frozen on a few hours measurement scale. We conclude that charge noise and the design of the gradient magnetic field are the key to further improve the qubit fidelity in isotopically purified 28Si/SiGe.

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Contributing Institute(s):

1. JARA Institut Quanteninformation (PGI-11)

Research Program(s):

1. 144 - Controlling Collective States (POF3-144) (POF3-144)

Appears in the scientific report 2020

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