A >99.9%-fidelity quantum-dot spin qubit with coherence limited by charge noise

J. Yoneda, K. Takeda, T. Otsuka, T. Nakajima, M. R. Delbecq, G. Allison, T. Honda, T. Kodera, S. Oda, Y. Hoshi, N. Usami, K. M. Itoh, S. Tarucha

Research output: Contribution to journalArticlepeer-review

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 susceptibility1-4, to extend spin coherence. In the meanwhile, addressable single-spin and spin-spin manipulations in multiple-qubit systems will necessitate sizable spin-electric coupling5-7. Given background charge fluctuation in nanostructures, however, its compatibility with enhanced coherence should be crucially questioned8-10. Here we realise a single-electron spin qubit with isotopically-enriched phase coherence time (20 μs)11,12 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.

Original languageEnglish
JournalUnknown Journal
Publication statusPublished - 2017 Aug 4

ASJC Scopus subject areas

  • General

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