Epitaxial NbN-junction-based self-shunted superconducting flux qubit with high anharmonicity

Abstract:We report a demonstration of a self-shunted superconducting flux qubit (SSFQ) as an ultracompact, strongly anharmonic, and long-lifetime qubit by using the full epitaxially grown NbN/AlN/NbN Josephson junctions. The NbN-junction-based SSFQ achieved a high anharmonicity of 797 MHz as well as drastically reduced footprint of the qubit compared to capacitively shunted (C-shunt) flux qubits with a large shunt capacitor. The lifetime of the SSFQ reached 13 - 25 $\mu$s, which is comparable to or relatively higher than that of NbN-based C-shunt flux qubits and Al-based flux qubits with more than 10 times smaller junctions. This indicates that the large epitaxial NbN-based junction can be adopted for SSFQ as well as merged-element transmon with the relatively large junctions. The results presented in this work will offer a new choice of the scalable qubits as well as the material platform toward the realization of large-scale superconducting quantum computers.

Quantum Physics (quant-ph); Superconductivity (cond-mat.supr-con)

arXiv:2610.04821 [quant-ph]

(or arXiv:2610.04821v1 [quant-ph] for this version)

https://doi.org/10.48550/arXiv.2610.04821 Focus to learn more arXiv-issued DOI via DataCite (pending registration)

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