An All-van-der-Waals Qubit

Year: 2026

Type: preprint

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 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 $T_{1,\mathrm{avg}} = 55 ~μs$, Hahn-echo coherence time $T_{2\mathrm{E},\mathrm{avg}} = 21 ~μs$, and Ramsey coherence time $T_{2\mathrm{R},\mathrm{avg}} = 1.9~μs$. 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$_\mathrm{x}$-Al qubits, while offering a reduced device footprint and suppressed stray capacitive coupling.

Source: arXiv (Cornell University)

DOI: 10.48550/arxiv.2609.14230

Institutions: Massachusetts Institute of Technology, National Institute for Materials Science, Research Center for Materials Nanoarchitectonics, Pohang University of Science and Technology, MIT Lincoln Laboratory, Harvard University, New York University

Language: English

Topic: Quantum Information and Cryptography

Subfield: Atomic and Molecular Physics, and Optics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: green

Funders: National Science Foundation, Gordon and Betty Moore Foundation, Schlumberger Foundation, Canadian Institute for Advanced Research, National Research Foundation, Ministry of Education, Culture, Sports, Science and Technology, National Research Foundation of Korea, Korea Foundation for Advanced Studies, Iran Telecommunication Research Center, Fundación Rafael del Pino, Samsung, U.S. Air Force, Japan Society for the Promotion of Science, Institute for Information and Communications Technology Promotion, Office of Naval Research, Core Research for Evolutional Science and Technology, Air Force Office of Scientific Research, Army Research Office

OpenAlex ID: W7213261016