An All-van-der-Waals Qubit
Abstract
Advances in solid-state physics, materials science, and device engineering have accelerated the development of superconducting qubits. Among emerging platforms, van der Waals (vdW) materials and their heterostructures are potentially attractive building blocks for quantum devices, yet their realization in qubit architectures remains largely underexplored. Here we report an all-vdW superconducting qubit based on a NbSe2-hBN-NbSe2 junction, in which a thin hBN layer simultaneously provides Josephson coupling and capacitive shunting between two NbSe2 islands, forming a "merged-element" transmon. Temporal characterization using circuit quantum electrodynamics (cQED) techniques yields an average energy-relaxation time T1,avg = 55 μs, Hahn-echo coherence time T2E,avg = 21 μs, and Ramsey coherence time T2R,avg = 1.9 μs. The relatively low Ramsey time is primarily attributable to an enhanced sensitivity to charge noise consistent with the realized device parameters and not a fundamental limitation. These results show that lumped-element superconducting qubits based on vdW heterostructures can achieve coherence times comparable to those of conventional Al-AlOx-Al qubits, while offering a reduced device footprint and suppressed stray capacitive coupling.
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BibTeX
@misc{park2026allvanderwaals,
title = {{An All-van-der-Waals Qubit}},
author = {Sein Park and Sameia Zaman and Junghyun Kim and Junyoung An and Daniel Rodan-Legrain and Hung-Yu Tsao and Chia-Chin Tsai and Aranya Goswami and Réouven Assouly and William P. Banner and Gabriel D. Cutter and Kenji Watanabe and Takashi Taniguchi and Terry P. Orlando and Gil-Ho Lee and Kyle Serniak and Max Hays and Jeffrey A. Grover and Philip Kim and Pablo Jarillo-Herrero and Joel Î-j. Wang and William D. Oliver},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.14230},
eprint = {2609.14230},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.14230},
}
RIS
TY - UNPB
TI - An All-van-der-Waals Qubit
AU - Sein Park
AU - Sameia Zaman
AU - Junghyun Kim
AU - Junyoung An
AU - Daniel Rodan-Legrain
AU - Hung-Yu Tsao
AU - Chia-Chin Tsai
AU - Aranya Goswami
AU - Réouven Assouly
AU - William P. Banner
AU - Gabriel D. Cutter
AU - Kenji Watanabe
AU - Takashi Taniguchi
AU - Terry P. Orlando
AU - Gil-Ho Lee
AU - Kyle Serniak
AU - Max Hays
AU - Jeffrey A. Grover
AU - Philip Kim
AU - Pablo Jarillo-Herrero
AU - Joel Î-j. Wang
AU - William D. Oliver
PY - 2026
DA - 2026/09/16
PB - arXiv
DO - 10.48550/arxiv.2609.14230
UR - https://arxiv.org/abs/2609.14230
AB - Advances in solid-state physics, materials science, and device engineering have accelerated the development of superconducting qubits. Among emerging platforms, van der Waals (vdW) materials and their heterostructures are potentially attractive building blocks for quantum devices, yet their realization in qubit architectures remains largely underexplored. Here we report an all-vdW superconducting qubit based on a NbSe_2-hBN-NbSe_2 junction, in which a thin hBN layer simultaneously provides Josephson coupling and capacitive shunting between two NbSe_2 islands, forming a "merged-element" transmon. Temporal characterization using circuit quantum electrodynamics (cQED) techniques yields an average energy-relaxation time T_1,avg = 55 μs, Hahn-echo coherence time T_2E,avg = 21 μs, and Ramsey coherence time T_2R,avg = 1.9 μs. The relatively low Ramsey time is primarily attributable to an enhanced sensitivity to charge noise consistent with the realized device parameters and not a fundamental limitation. These results show that lumped-element superconducting qubits based on vdW heterostructures can achieve coherence times comparable to those of conventional Al-AlO_x-Al qubits, while offering a reduced device footprint and suppressed stray capacitive coupling.
ER -