Article Dans Une Revue Nature Communications Année : 2025

Gate- and flux-tunable sin(2φ) Josephson element with planar-Ge junctions

Résumé

Hybrid superconductor-semiconductor Josephson field-effect transistors (JoFETs) function as Josephson junctions with gate-tunable critical current. Additionally, they can feature a non-sinusoidal current-phase relation (CPR) containing multiple harmonics of the superconducting phase difference, a so-far underutilized property. Here we exploit this multi-harmonicity to create a Josephson circuit element with an almost perfectly π-periodic CPR, indicative of a largely dominant charge-4e supercurrent transport. We realize such a Josephson element, recently proposed as building block of a protected superconducting qubit, using a superconducting quantum interference device (SQUID) with low-inductance aluminum arms and two nominally identical JoFETs. The latter are fabricated from a SiGe/Ge/SiGe quantum-well heterostructure embedding a high-mobility two-dimensional hole gas. By carefully adjusting the JoFET gate voltages and finely tuning the magnetic flux through the SQUID close to half a flux quantum, we achieve a regime where the component accounts for more than 95% of the total supercurrent. This result demonstrates a new promising route towards parity-protected superconducting qubits.
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Dates et versions

hal-04913025 , version 1 (29-01-2025)

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Axel Leblanc, Chotivut Tangchingchai, Zahra Sadre Momtaz, Elyjah Kiyooka, Jean-Michel Hartmann, et al.. Gate- and flux-tunable sin(2φ) Josephson element with planar-Ge junctions. Nature Communications, 2025, 16 (1), pp.1010. ⟨10.1038/s41467-025-56245-7⟩. ⟨hal-04913025⟩
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