December 19, 2017
Japan Science and Technology Agency (JST)
RIKEN
The University of Tokyo
Tokyo Institute of Technology
Keio University
Highlights
Demonstrated a method for achieving both high-speed quantum operations and long information retention times for electron spins in a solid state.
Achieved the world's highest level of quantum operation fidelity for an integrable qubit in a silicon device.
This is expected to accelerate the development of quantum computers using electron spins in silicon.
Under the JST Strategic Basic Research Programs, a research group led by Seigo Tarucha, Group Director at RIKEN and Professor at the School of Engineering, The University of Tokyo, and Jun Yoneda, Special Postdoctoral Researcher at RIKEN, has developed an electron spin qubit device in a silicon quantum dot with the world's highest level of operational fidelity.
Quantum computers are attracting attention as candidates for the next generation of computers, and a global race is intensifying to develop qubits, the carriers of quantum information, in various systems, led by superconducting devices. While the implementation of qubits using semiconductor devices is important from the perspective of industrial application, achieving both high-speed quantum operations and long information retention times has been difficult, making performance enhancement a major challenge.
The research group fabricated a quantum dot device using an isotopically controlled silicon substrate with extremely low magnetic noise, newly developed by Professor Kohei Itoh of Keio University and Professor Noritaka Usami of Nagoya University. By combining this with high-speed spin manipulation using a micromagnet of a special shape, they simultaneously achieved an operation speed approximately 100 times faster and an information retention time about 10 times longer than conventional qubits, successfully reducing the quantum operation error rate by about an order of magnitude. Through the application of semiconductor isotope technology, they revealed for the first time that the loss of quantum information for electron spins in this device is dominated by charge noise, rather than the usual magnetic noise.
This research establishes a method for implementing ultra-high-performance electron spin qubits in silicon nanostructures suitable for industrial integration, and is expected to accelerate the development of silicon quantum computers using this technology.
This research was conducted in collaboration with Associate Professor Tetsuo Kodera of the Tokyo Institute of Technology, Professor Kohei Itoh of Keio University, and Professor Noritaka Usami of Nagoya University.
This research will be published in the online advance edition of the international scientific journal *Nature Nanotechnology* on December 18, 2017 (UK time).
For the full press release, please see below.