Gatemon qubit on a germanium quantum-well heterostructure

Abstract

Gatemons are superconducting qubits resembling transmons, with a gate-tunable semiconducting weak link as the Josephson element. Here, we report a gatemon device featuring an aluminum microwave circuit on a Ge/SiGe heterostructure embedding a Ge quantum well. Owing to the superconducting proximity effect, the high-mobility two-dimensional hole gas confined in this well provides a gate-tunable superconducting weak link between two Al contacts. We perform Rabi oscillation and Ramsey interference measurements, demonstrate the gate-voltage dependence of the qubit frequency, and measure the qubit anharmonicity. We find relaxation times T${}_1$ up to 119 ns, and Ramsey coherence times T${}_2^{\ast }$ up to 70 ns, and a qubit frequency gate-tunable over 3.5 GHz. The reported proof-of-concept reproduces the results of a very recent work [Sagi et al., Nat. Commun. 15, 6400 (2024)] using similar Ge/SiGe heterostructures thereby validating a novel platform for the development of gatemons and parity-protected cos(2$\varphi$) qubits.

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Cited by in corpus (6)

• The carbon nanotube gatemon qubit
• Superconducting Proximity Effect in Two-Dimensional Hole Gases
• Theory of superconducting proximity effect in hole-based hybrid semiconductor-superconductor devices
• Supercurrent and multiple Andreev reflections in Ge hut nanowire Josephson Junctions
• Strongly anharmonic flux-tunable transmon based on InAs-Al 2D heterostructure
• Gate- and flux-tunable sin(2$\phi$) Josephson element with proximitized Ge-based junctions