ORCID Profile
0000-0001-7465-0135
Current Organisations
RIKEN Center for Emergent Matter Science
,
University of Tokyo
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Publisher: Springer Science and Business Media LLC
Date: 24-08-2022
DOI: 10.1038/S41586-022-04986-6
Abstract: Future large-scale quantum computers will rely on quantum error correction (QEC) to protect the fragile quantum information during computation 1,2 . Among the possible candidate platforms for realizing quantum computing devices, the compatibility with mature nanofabrication technologies of silicon-based spin qubits offers promise to overcome the challenges in scaling up device sizes from the prototypes of today to large-scale computers 3–5 . Recent advances in silicon-based qubits have enabled the implementations of high-quality one-qubit and two-qubit systems 6–8 . However, the demonstration of QEC, which requires three or more coupled qubits 1 , and involves a three-qubit gate 9–11 or measurement-based feedback, remains an open challenge. Here we demonstrate a three-qubit phase-correcting code in silicon, in which an encoded three-qubit state is protected against any phase-flip error on one of the three qubits. The correction to this encoded state is performed by a three-qubit conditional rotation, which we implement by an efficient single-step resonantly driven iToffoli gate. As expected, the error correction mitigates the errors owing to one-qubit phase-flip, as well as the intrinsic dephasing mainly owing to quasi-static phase noise. These results show successful implementation of QEC and the potential of a silicon-based platform for large-scale quantum computing.
Publisher: Springer Science and Business Media LLC
Date: 30-09-2022
DOI: 10.1038/S41467-022-33453-Z
Abstract: Control of entanglement between qubits at distant quantum processors using a two-qubit gate is an essential function of a scalable, modular implementation of quantum computation. Among the many qubit platforms, spin qubits in silicon quantum dots are promising for large-scale integration along with their nanofabrication capability. However, linking distant silicon quantum processors is challenging as two-qubit gates in spin qubits typically utilize short-range exchange coupling, which is only effective between nearest-neighbor quantum dots. Here we demonstrate a two-qubit gate between spin qubits via coherent spin shuttling, a key technology for linking distant silicon quantum processors. Coherent shuttling of a spin qubit enables efficient switching of the exchange coupling with an on/off ratio exceeding 1000, while preserving the spin coherence by 99.6% for the single shuttling between neighboring dots. With this shuttling-mode exchange control, we demonstrate a two-qubit controlled-phase gate with a fidelity of 93%, assessed via randomized benchmarking. Combination of our technique and a phase coherent shuttling of a qubit across a large quantum dot array will provide feasible path toward a quantum link between distant silicon quantum processors, a key requirement for large-scale quantum computation.
Publisher: Springer Science and Business Media LLC
Date: 06-2023
DOI: 10.1038/S41534-023-00719-3
Abstract: Feedback control of qubits is a highly demanded technique for advanced quantum information protocols such as fault-tolerant quantum error correction. Here we demonstrate active reset of a silicon spin qubit using feedback control. The active reset is based on quantum non-demolition (QND) readout of the qubit and feedback according to the readout results, which is enabled by hardware data processing and sequencing. We incorporate a cumulative readout technique to the active reset protocol, enhancing initialization fidelity above a limitation imposed by the single-shot QND readout fidelity. An analysis of the reset protocol implies a pathway to achieve the initialization fidelity sufficient for fault-tolerant quantum computation. These results provide a practical approach to high-fidelity qubit operations in realistic devices.
Publisher: Springer Science and Business Media LLC
Date: 11-2022
Publisher: Springer Science and Business Media LLC
Date: 09-10-2023
Publisher: Springer Science and Business Media LLC
Date: 19-01-2022
DOI: 10.1038/S41586-021-04182-Y
Abstract: Fault-tolerant quantum computers that can solve hard problems rely on quantum error correction
Publisher: American Physical Society (APS)
Date: 06-12-2022
No related grants have been discovered for Seigo Tarucha.