Disorder in the heterogeneous material stack of semiconductor spin qubit systems introduces noise that compromises quantum information processing, posing a challenge to coherently control large-scale quantum devices. Here, we exploit low-disorder epitaxial strained quantum wells in Ge/SiGe heterostructures grown on Ge wafers to comprehensively probe the noise properties of complex micron-scale devices comprising of up to ten quantum dots and four rf-charge sensors arranged in a two-dimensional array. We demonstrate an average charge noise of S0=0.3(1)μeV/Hz at 1 Hz across different locations on the wafer, providing a benchmark for quantum confined holes. We then establish hole-spin qubit control in these heterostructures and extend our investigation from electrical to magnetic noise through spin echo measurements. Exploiting dynamical decoupling sequences, we quantify the power spectral density components arising from the hyperfine interaction with 73Ge spinful isotopes and identify coherence modulations associated with the interaction with the 29Si nuclear spin bath near the Ge quantum well. We estimate an integrated hyperfine noise amplitude σf of 180(8) kHz from 73Ge and of 47(5) kHz from 29Si, underscoring the need for full isotopic purification of the qubit host environment.
@article{arxiv.2411.11526,
title = {Exploiting epitaxial strained germanium for scaling low noise spin qubits at the micron-scale},
author = {Lucas E. A. Stehouwer and Cécile X. Yu and Barnaby van Straaten and Alberto Tosato and Valentin John and Davide Degli Esposti and Asser Elsayed and Davide Costa and Stefan D. Oosterhout and Nico W. Hendrickx and Menno Veldhorst and Francesco Borsoi and Giordano Scappucci},
journal= {arXiv preprint arXiv:2411.11526},
year = {2025}
}