Fujitsu advances diamond photonics
Fujitsu has developed a diamond-spin quantum computing prototype integrating tin-vacancy centres with photonic circuits, using optical connectivity to support scalable quantum architectures.
Fujitsu has developed a working diamond-spin quantum computer prototype that integrates tin-vacancy (SnV) colour centres with photonic integrated circuits (PICs), creating an architecture designed to support scalable and modular quantum computing.
The prototype operates at -271.6°C and uses SnV centres in diamond as qubits. The centres offer stable quantum states and can emit single photons, making them suitable for both quantum information processing and optical communication between quantum modules.
A key element of the architecture is the integration of the diamond-based qubits with photonic circuitry. Fujitsu developed a heterogeneous bonding process to attach diamond substrates containing implanted tin to alumina and silicon-dioxide substrates.
The diamond is then thinned from several hundred micrometres to several hundred nanometres, enabling integration into a compact photonic platform.
The resulting structure incorporates nanometre-scale diamond crystals containing SnV centres alongside alumina optical waveguides. The waveguides can collect photons emitted by the SnV centres during qubit readout and provide an optical interface for transferring quantum information.
This optical connectivity could allow individual quantum modules to be linked without requiring all qubits to be placed on a single large processor. Such a modular approach is intended to address one of the key challenges in scaling quantum computing systems.
The prototype also incorporates optical, microwave and radio-frequency control. Fujitsu has developed a circuit-conversion mechanism that translates quantum gates into the physical control sequences required to operate the diamond-spin qubits.
The system can be operated through Fujitsu's Hybrid Quantum Computing Platform, providing an interface between the quantum processor and higher-level quantum applications.
The work follows a research collaboration between Fujitsu, Delft University of Technology and QuTech that began in 2020. Fujitsu plans to develop a multi-module diamond-spin quantum computer prototype by 2027, while also investigating the combination of diamond-spin and superconducting quantum technologies.
The integration of diamond quantum devices with PICs highlights the potential of photonic technologies to provide the optical readout and interconnect infrastructure required for future modular quantum processors.
