Coherent charge oscillations in a bilayer graphene double quantum dot

• Published in: Nature communications Vol. 14; no. 1; p. 7911
• Main Authors: Hecker, K., Banszerus, L., Schäpers, A., Möller, S., Peters, A., Icking, E., Watanabe, K., Taniguchi, T., Volk, C., Stampfer, C.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 30-11-2023; Nature Publishing Group; Nature Portfolio
• Subjects: 639/766/119/1000/1017; 639/766/483/2802; 639/925/918/1052; Bilayers; Charge distribution; Charge materials; Coherence; Energy levels; Graphene; Humanities and Social Sciences; Interference; multidisciplinary; Oscillations; Quantum dots; Quantum mechanics; Qubits (quantum computing); Science; Science (multidisciplinary); Spectroscopy
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-023-43541-3

The coherent dynamics of a quantum mechanical two-level system passing through an anti-crossing of two energy levels can give rise to Landau-Zener-Stückelberg-Majorana (LZSM) interference. LZSM interference spectroscopy has proven to be a fruitful tool to investigate charge noise and charge decoherence in semiconductor quantum dots (QDs). Recently, bilayer graphene has developed as a promising platform to host highly tunable QDs potentially useful for hosting spin and valley qubits. So far, in this system no coherent oscillations have been observed and little is known about charge noise in this material. Here, we report coherent charge oscillations and
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charge decoherence times in a bilayer graphene double QD. The charge decoherence times are measured independently using LZSM interference and photon assisted tunneling. Both techniques yield
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average values in the range of 400–500 ps. The observation of charge coherence allows to study the origin and spectral distribution of charge noise in future experiments.
Graphene quantum dots promise applications for spin and valley qubits; however a demonstration of phase coherent oscillations has been lacking. Here the authors report coherent charge oscillations and measurements of coherence times in highly tuneable double quantum dots in bilayer graphene.