1. A quantum-dot spin qubit with coherence limited by charge noise and fidelity higher than 99.9%
- Author
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Shunri Oda, Seigo Tarucha, Kohei M. Itoh, Yusuke Hoshi, Giles Allison, Kenta Takeda, Jun Yoneda, Tetsuo Kodera, Noritaka Usami, Takumu Honda, M. R. Delbecq, Tomohiro Otsuka, and Takashi Nakajima
- Subjects
Physics ,Spins ,Dephasing ,Biomedical Engineering ,Bioengineering ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Controllability ,Microsecond ,Quantum dot ,Quantum mechanics ,Qubit ,0103 physical sciences ,Condensed Matter::Strongly Correlated Electrons ,General Materials Science ,Electrical and Electronic Engineering ,010306 general physics ,0210 nano-technology ,Quantum computer ,Coherence (physics) - Abstract
Recent advances towards spin-based quantum computation have been primarily fuelled by elaborate isolation from noise sources, such as surrounding nuclear spins and spin-electric susceptibility, to extend spin coherence. In the meanwhile, addressable single-spin and spin-spin manipulations in multiple-qubit systems will necessitate sizable spin-electric coupling. Given background charge fluctuation in nanostructures, however, its compatibility with enhanced coherence should be crucially questioned. Here we realise a single-electron spin qubit with isotopically-enriched phase coherence time (20 microseconds) and fast electrical control speed (up to 30 MHz) mediated by extrinsic spin-electric coupling. Using rapid spin rotations, we reveal that the free-evolution dephasing is caused by charge (instead of conventional magnetic) noise featured by a 1/f spectrum over seven decades of frequency. The qubit nevertheless exhibits superior performance with single-qubit gate fidelities exceeding 99.9% on average. Our work strongly suggests that designing artificial spin-electric coupling with account taken of charge noise is a promising route to large-scale spin-qubit systems having fault-tolerant controllability.
- Published
- 2017