The carbon nanotube gatemon qubit

H. Riechert; S. Annabi; A. Peugeot; H. Duprez; M. Hantute; K. Watanabe; T. Taniguchi; E. Arrighi; J. Griesmar; J. -D. Pillet; L. Bretheau

doi:10.1038/s41467-025-62283-y

arXiv · 2503.01978

The carbon nanotube gatemon qubit

H. Riechert·S. Annabi·A. Peugeot·H. Duprez·M. Hantute·K. Watanabe·T. Taniguchi·E. Arrighi·J. Griesmar·J. -D. Pillet·L. Bretheau

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Abstract

Gate-tunable transmon qubits are based on quantum conductors used as weak links within hybrid Josephson junctions. These gatemons have been implemented in just a handful of systems, all relying on extended conductors, namely epitaxial semiconductors or exfoliated graphene. Here we present the coherent control of a gatemon based on a single molecule, a one-dimensional carbon nanotube, which is integrated into a circuit quantum electrodynamics architecture. The measured qubit spectrum can be tuned with a gate voltage and reflects the quantum dot behaviour of the nanotube. Our ultraclean integration, using a hexagonal boron nitride substrate, results in record coherence times of 200ns for carbon nanotube-based qubits. Furthermore, we investigate its decoherence mechanisms, thus revealing a strong gate dependence and identifying charge noise as a limiting factor. On top of positioning carbon nanotubes as contenders for future quantum technologies, our work paves the way for studying microscopic fermionic processes in low-dimensional quantum conductors.

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H. Riechert, S. Annabi, A. Peugeot, H. Duprez, M. Hantute, K. Watanabe, T. Taniguchi, E. Arrighi, J. Griesmar, J. -D. Pillet, L. Bretheau. 2025-03-03. The carbon nanotube gatemon qubit. https://doi.org/10.1038/s41467-025-62283-y

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