Optimising germanium hole spin qubits with a room-temperature magnet

Fuente: arXiv
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Autores principales: Yu, Cecile X., van Straaten, Barnaby, Ivlev, Alexander S., John, Valentin, Oosterhout, Stefan D., Stehouwer, Lucas E. A., Borsoi, Francesco, Scappucci, Giordano, Veldhorst, Menno
Formato: Preprint
Publicado: 2025
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author Yu, Cecile X.
van Straaten, Barnaby
Ivlev, Alexander S.
John, Valentin
Oosterhout, Stefan D.
Stehouwer, Lucas E. A.
Borsoi, Francesco
Scappucci, Giordano
Veldhorst, Menno
author_facet Yu, Cecile X.
van Straaten, Barnaby
Ivlev, Alexander S.
John, Valentin
Oosterhout, Stefan D.
Stehouwer, Lucas E. A.
Borsoi, Francesco
Scappucci, Giordano
Veldhorst, Menno
contents Germanium spin qubits exhibit strong spin-orbit interaction, which allow for high-fidelity qubit control, but also provide a strong dependence on the magnetic field. Superconducting vector magnets are often used to minimize dephasing due to hyperfine interactions and to maximize spin control, but these compromise the sample space and thus challenge scalability. Here, we explore whether a permanent magnet outside the cryostat can be used as an alternative. Operating in a hybrid mode with an internal and external magnet, we find that we can fine-tune the magnetic field to an in-plane orientation. We obtain a qubit dephasing time T2*=13 microseconds, Hahn-echo times T2H=88 microseconds, and an average single-qubit Clifford gate fidelity above 99.9%, from which we conclude that room temperature magnets allow for high qubit performance. Furthermore, we probe the qubit resonance frequency using only the external magnet, with the internal superconducting magnet switched off. Our approach may be used to scale semiconductor qubits and use the increased sample space for the integration of cryogenic control circuitry and wiring to advance to large-scale quantum processors.
format Preprint
id arxiv_https___arxiv_org_abs_2507_03390
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Optimising germanium hole spin qubits with a room-temperature magnet
Yu, Cecile X.
van Straaten, Barnaby
Ivlev, Alexander S.
John, Valentin
Oosterhout, Stefan D.
Stehouwer, Lucas E. A.
Borsoi, Francesco
Scappucci, Giordano
Veldhorst, Menno
Quantum Physics
Mesoscale and Nanoscale Physics
Materials Science
Applied Physics
Germanium spin qubits exhibit strong spin-orbit interaction, which allow for high-fidelity qubit control, but also provide a strong dependence on the magnetic field. Superconducting vector magnets are often used to minimize dephasing due to hyperfine interactions and to maximize spin control, but these compromise the sample space and thus challenge scalability. Here, we explore whether a permanent magnet outside the cryostat can be used as an alternative. Operating in a hybrid mode with an internal and external magnet, we find that we can fine-tune the magnetic field to an in-plane orientation. We obtain a qubit dephasing time T2*=13 microseconds, Hahn-echo times T2H=88 microseconds, and an average single-qubit Clifford gate fidelity above 99.9%, from which we conclude that room temperature magnets allow for high qubit performance. Furthermore, we probe the qubit resonance frequency using only the external magnet, with the internal superconducting magnet switched off. Our approach may be used to scale semiconductor qubits and use the increased sample space for the integration of cryogenic control circuitry and wiring to advance to large-scale quantum processors.
title Optimising germanium hole spin qubits with a room-temperature magnet
topic Quantum Physics
Mesoscale and Nanoscale Physics
Materials Science
Applied Physics
url https://arxiv.org/abs/2507.03390