Exploiting epitaxial strained germanium for scaling low noise spin qubits at the micron-scale

Abstract

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 $\sqrt{S_0}=0.3(1)$ $\mu \mathrm{eV}/\sqrt{\mathrm{Hz}}$ 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 ${}^{73}$Ge spinful isotopes and identify coherence modulations associated with the interaction with the ${}^{29}$Si nuclear spin bath near the Ge quantum well. We estimate an integrated hyperfine noise amplitude ${\sigma }_f$ of 180(8) kHz from ${}^{73}$Ge and of 47(5) kHz from ${}^{29}$Si, underscoring the need for full isotopic purification of the qubit host environment.

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Cited by in corpus (5)

• A two-dimensional 10-qubit array in germanium with robust and localised qubit control
• Cancelling second order frequency shifts in Ge hole spin qubits via bichromatic control
• Ge as an orbitronic platform: giant in-plane orbital magneto-electric effect in a 2-dimensional hole gas
• Switchable spin-photon coupling with hole spins in single-quantum dots
• Orbital Hall effect in spin-3/2 hole-doped semiconductors and its implications for orbitronics