title: A fault-tolerant addressable spin qubit in a natural silicon quantum dot.
abstract: Fault-tolerant quantum computing requires high-fidelity qubits. This has been achieved in various solid-state systems, including isotopically purified silicon, but is yet to be accomplished in industry-standard natural (unpurified) silicon, mainly as a result of the dephasing caused by residual nuclear spins. This high fidelity can be achieved by speeding up the qubit operation and/or prolonging the dephasing time, that is, increasing the Rabi oscillation quality factor Q (the Rabi oscillation decay time divided by the π rotation time). In isotopically purified silicon quantum dots, only the second approach has been used, leaving the qubit operation slow. We apply the first approach to demonstrate an addressable fault-tolerant qubit using a natural silicon double quantum dot with a micromagnet that is optimally designed for fast spin control. This optimized design allows access to Rabi frequencies up to 35 MHz, which is two orders of magnitude greater than that achieved in previous studies. We find the optimum Q = 140 in such high-frequency range at a Rabi frequency of 10 MHz. This leads to a qubit fidelity of 99.6% measured via randomized benchmarking, which is the highest reported for natural silicon qubits and comparable to that obtained in isotopically purified silicon quantum dot-based qubits. This result can inspire contributions to quantum computing from industrial communities.
authors.affiliation: RIKEN, Center for Emergent Matter Science, Wako-shi, Saitama 351-0198, Japan.
authors.forename: Kenta
authors.initials: K
authors.lastname: Takeda
authors.affiliation: Department of Physical Electronics and Quantum Nanoelectronics Research Center, Tokyo Institute of Technology, O-okayama, Meguro-ku, Tokyo 152-8552, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Kamioka
authors.affiliation: RIKEN, Center for Emergent Matter Science, Wako-shi, Saitama 351-0198, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Otsuka
authors.affiliation: RIKEN, Center for Emergent Matter Science, Wako-shi, Saitama 351-0198, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Yoneda
authors.affiliation: RIKEN, Center for Emergent Matter Science, Wako-shi, Saitama 351-0198, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakajima
authors.affiliation: RIKEN, Center for Emergent Matter Science, Wako-shi, Saitama 351-0198, Japan.
authors.forename: Matthieu R
authors.initials: MR
authors.lastname: Delbecq
authors.affiliation: RIKEN, Center for Emergent Matter Science, Wako-shi, Saitama 351-0198, Japan.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Amaha
authors.affiliation: RIKEN, Center for Emergent Matter Science, Wako-shi, Saitama 351-0198, Japan.
authors.forename: Giles
authors.initials: G
authors.lastname: Allison
authors.affiliation: Department of Physical Electronics and Quantum Nanoelectronics Research Center, Tokyo Institute of Technology, O-okayama, Meguro-ku, Tokyo 152-8552, Japan.
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Kodera
authors.affiliation: Department of Physical Electronics and Quantum Nanoelectronics Research Center, Tokyo Institute of Technology, O-okayama, Meguro-ku, Tokyo 152-8552, Japan.
authors.forename: Shunri
authors.identifier: 0000-0002-8009-2077
authors.initials: S
authors.lastname: Oda
authors.affiliation: RIKEN, Center for Emergent Matter Science, Wako-shi, Saitama 351-0198, Japan.; Department of Applied Physics, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Seigo
authors.initials: S
authors.lastname: Tarucha
mesh_terms: D008962:Models, Theoretical; D036103:Nanotechnology; D045663:Quantum Dots / Q000737:chemistry*; D012825:Silicon / Q000737:chemistry*
chemical_list: D012825:Silicon
keywords: Nanotechnology; Si/SiGe; Silicon; physics; quantum dot; qubit; spin qubit