Fujitsu develops diamond-spin quantum computer prototype - Engineer Live

Fujitsu has developed a prototype diamond-spin quantum computer that incorporates tin-vacancy (SnV) centres into photonic integrated circuits The prototype can operate at -271.6°C, higher than the typical operating temperature of a superconducting quantum computer, and Fujitsu has demonstrated in a test environment that it can be used via the Fujitsu Hybrid Quantum Computing Platform without additional specialist knowledge. This development marks a significant milestone toward a modular architecture, one of the most promising approaches for scaling quantum computers, thanks to its high fidelity and efficient optical connectivity. The prototype builds on joint research started in 2020 by Fujitsu, Delft University of Technology, and QuTech, a quantum technology research institute part of TU Delft. Fujitsu will develop a prototype of a multi-module diamond-spin quantum computer by 2027. Fujitsu will also begin developing technologies to integrate the diamond-spin with a superconducting approach, accelerating progress toward large-scale quantum computers. This initiative is part of Fujitsu’s quantum roadmap, which outlines the company’s aim to realise practical quantum computing by 2030. Vivek Mahajan, corporate executive officer, corporate vice president, CTO, in charge of System Platform, Fujitsu Limited, said, “The diamond-spin approach we have applied in this prototype not only offers exceptional scalability in its own right, but also has the potential to be integrated with superconducting quantum computers to further extend their capabilities, enabling more complex and large-scale computations. “Under our roadmap to achieve a 250 logical qubit system by fiscal 2030 and a 1,000 logical qubit system by fiscal 2035, Fujitsu will continue advancing practical quantum computing across a broad range of areas, from software to hardware, while leveraging the key advantages of the diamond-spin approach, including high fidelity and optical connectivity.” Dr Kees Eijkel, general director, QuTech, Delft University of Technology, said, “We are delighted to announce this prototype diamond spin quantum computer as a result of the collaborative research conducted since 2020 between Fujitsu, Delft University of Technology, and QuTech. It is a major milestone in our strong collaboration. Demonstrating the scalability expected of diamond spin quantum computing remains a long and challenging journey. However, by further strengthening our collaboration with Fujitsu, we are committed to tackling this ambitious and meaningful challenge and leading the development of next-generation quantum technologies.” The prototype features three technologies from Fujitsu Heterogeneous material bonding and thinning technology for scalable quantum computing chips To create quantum computing chips using SnV centres, Fujitsu developed heterogeneous material bonding technology to bond high-quality diamond substrates ion-implanted with tin to alumina/silicon dioxide substrates. Fujitsu also developed thinning technology to reduce diamond substrate thickness from several hundred micrometres to several hundred nanometres, making them suitable for quantum computing chips. Photonics-integrated circuit fabrication technology for SnV centres Fujitsu developed technology to fabricate photonics integrated circuits that integrate nanometre-sized diamond crystals containing SnV centres with alumina optical waveguides, which are transparent in the visible light region, to extract single photons emitted from SnV centres during qubit readout. For diamond processing, Fujitsu used the results of joint research with the University of Tokyo. Quantum circuit conversion technology for diamond spin approach The diamond-spin approach requires qubit control by combining light, microwaves, and radio frequency waves. Fujitsu developed a mechanism to convert quantum circuits described by quantum gates into control sequences for these physical operations for the diamond-spin approach, enabling control from Fujitsu’s hybrid quantum computing platform. Background The diamond-spin approach uses lattice defect structures called colour centres in diamond crystals as qubits. This approach achieves high fidelity because diamond has inherent properties that keep quantum states stable and could allow logical qubits to be reliably formed from fewer physical qubits than in superconducting and other approaches. Furthermore, light can flexibly connect multiple quantum modules, enabling a modular architecture that can scale efficiently. Typically, the diamond-spin approach uses nitrogen-vacancy (NV) centres, formed by nitrogen impurities in diamond crystals. However, in developing this prototype, Fujitsu used tin-vacancy (SnV) centres, which have higher structural symmetry and are less susceptible to external noise than NV centres, making them attractive candidates for stable, high-brightness colour centres. Research Support A part of this work is supported by “Advanced Research Infrastructure for Materials and Nanotechnology in Japan (ARIM)” of the Ministry of Education, Culture, Sports, Science and Technology (MEXT). Proposal Number JPMXP1225NM0096.

This research project is a collaboration between QuTech and Fujitsu, co-financed by Holland High Tech with a PPP allowance for research and development in the top sector HTSM and a PPP allowance for research and innovation from the Ministry of Economic Affairs.

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