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

@misc{uchida2026epitaxial,
  title = {{Epitaxial NbN-junction-based self-shunted superconducting flux qubit with high anharmonicity}},
  author = {Tokunoshin Uchida and Shingo Nozaki and Daiki Kurihara and Hiroki Kutsuma and Shotaro Shirai and Atsushi Noguchi and Hirotaka Terai and Taro Yamashita},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.04821},
  eprint = {2610.04821},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.04821},
}

TY  - UNPB
TI  - Epitaxial NbN-junction-based self-shunted superconducting flux qubit with high anharmonicity
AU  - Tokunoshin Uchida
AU  - Shingo Nozaki
AU  - Daiki Kurihara
AU  - Hiroki Kutsuma
AU  - Shotaro Shirai
AU  - Atsushi Noguchi
AU  - Hirotaka Terai
AU  - Taro Yamashita
PY  - 2026
DA  - 2026/10/04
PB  - arXiv
DO  - 10.48550/arxiv.2610.04821
UR  - https://arxiv.org/abs/2610.04821
AB  - 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 μs, 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.
ER  -