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TY  - THES
AU  - Leonhardt, Tim
TI  - Development of device design, processing, and instrumentation for scaleable universal quantum computation in silicon germanium heterostructures
PB  - RWTH Aachen University
VL  - Dissertation
CY  - Aachen
M1  - RWTH-2025-00668
SP  - 1 Online-Ressource : Illustrationen
PY  - 2024
N1  - Veröffentlicht auf dem Publikationsserver der RWTH Aachen University 2025
N1  - Dissertation, RWTH Aachen University, 2024
AB  - In this thesis, a measurement and control setup for Elzerman readout and silicon spin qubit experiments, like T1 measurements, is designed and optimized. Developments in amplifier choice and testing, impedance matching, and thedesign and concept of an interposer-PCB integration platform result in a low noise, high-bandwidth setup which, after first characterizations, is sufficient for experiments on universal control in silicon quantum dots. Remaining dominant contributions are identified. For critical thermalization with single-spin qubit readout, we have designed and produced multiple cryogenic filters for up to 192 DC lines with transmission characteristics comparable to less scalable PCB solutions. The identified and resolved limitations allow for Elzerman readout at below 1.5 T. Developments in electron beam fabrication enable the smallest gate pitch reported for gate-confined single-layer quantum dots. Asetup and tuning protocol is revised to identify dis-functional samples early in the tuning process. The low-frequency noise within the 10-kHz measurement bandwidth for undoped MBE structures is significantly lower in our sample than in previously reported CVD samples. A triangulation method has been developed and improved to quantify the influence of the displacement, the respective electric field strength due to disorder charges and subsequently define limits on defect localization in the sample stack. These are consistent with estimates from other work. These experiments show that the MBE-grown heterostructures, sample fabrication, and measurement setup are suitable for silicon single-spin experiments and provide a direction to further improve reliability, tunability, and fidelity of laterally defined qubits in undoped silicon heterostructures.
LB  - PUB:(DE-HGF)11
DO  - DOI:10.18154/RWTH-2025-00668
UR  - https://publications.rwth-aachen.de/record/1002761
ER  -