Sweet-spot operation of a germanium hole spin qubit with highly anisotropic noise sensitivity

Spin qubits defined by valence band hole states are attractive for quantum information processing due to their inherent coupling to electric fields, enabling fast and scalable qubit control. Heavy holes in germanium are particularly promising, with recent demonstrations of fast and high-fidelity qub...

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Bibliographic Details
Published in:Nature materials 2024-07, Vol.23 (7), p.920-927
Main Authors: Hendrickx, N. W., Massai, L., Mergenthaler, M., Schupp, F. J., Paredes, S., Bedell, S. W., Salis, G., Fuhrer, A.
Format: Article
Language:English
Subjects:
639/301/119/1000/1017
639/301/119/995
639/766/483/2802
639/925/927/1007
639/925/927/481
Biomaterials
Chemistry and Materials Science
Coherence
Condensed Matter Physics
Data processing
Electric fields
Germanium
High temperature
Ising model
Magnetic fields
Materials Science
Nanotechnology
Noise sensitivity
Optical and Electronic Materials
Quantum phenomena
Qubits (quantum computing)
Tensors
Valence band
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Summary:Spin qubits defined by valence band hole states are attractive for quantum information processing due to their inherent coupling to electric fields, enabling fast and scalable qubit control. Heavy holes in germanium are particularly promising, with recent demonstrations of fast and high-fidelity qubit operations. However, the mechanisms and anisotropies that underlie qubit driving and decoherence remain mostly unclear. Here we report the highly anisotropic heavy-hole g -tensor and its dependence on electric fields, revealing how qubit driving and decoherence originate from electric modulations of the g -tensor. Furthermore, we confirm the predicted Ising-type hyperfine interaction and show that qubit coherence is ultimately limited by 1/ f charge noise, where f is the frequency. Finally, operating the qubit at low magnetic field, we measure a dephasing time of T 2 *  = 17.6 μs, maintaining single-qubit gate fidelities well above 99% even at elevated temperatures of T  > 1 K. This understanding of qubit driving and decoherence mechanisms is key towards realizing scalable and highly coherent hole qubit arrays. The authors report the sweet-spot operation of germanium hole spin qubits, exploring the optimization of the external magnetic field orientation, the g -tensor and its electric tunability, and hyperfine interactions.
ISSN:1476-1122
1476-4660
1476-4660
DOI:10.1038/s41563-024-01857-5