In a new work being presented at the IEEE 2024 IEEE Silicon Nanoelectronics Workshop this month, Diraq has achieved record fidelity for spin qubits fabricated on a 300 mm wafer by imec. They have seen single qubit gate fidelities of 99.9%. In previous work published in Nature Magazine they have also demonstrated high fidelities when operating a 1 Kelvin. Operation at the 1 Kelvin rather than 10 or 15 millikelvin temperatures is important due to Diraq’s strategy of creating chips with a large number of qubits. Dilution refrigerators like those used in superconducting designs have a relatively small cooling power and cost hundreds of thousands of dollars. Even though these qubits dissipate a very small amount of power, the overall number of qubits that can be contained in a dilution refrigerator will be still be limited by the ability to keep them all cool. By operating at 1 Kelvin, a quantum computer can use a much less costly cryostats that have orders of magnitude more cooling power at the higher temperature.
Previously, Diraq had been fabricating test chips at the Australian National Fabrication Facility in Sydney. But now, they have demonstrated that their devices can also be fabricated in a standard CMOS industry manufacturing line on 300 mm wafers with as good or better results. The high single-qubit fidelity, the best to date for silicon spin qubits made in a 300mm foundry environment, is enabled by Diraq’s sophisticated qubit control and measurement techniques. These include real-time feedback, optimized qubit initialization, control voltage pulse shaping, and advanced analysis tools such as gate set tomography and randomized benchmarking. Diraq is continuing their evaluations of these new devices to also assess the fidelities they can achieve with two-qubit gates.
Also, Diraq has announced that it is working with GlobalFoundries for development of devices that integrate CMOS transistors with qubits on the same chip. These runs will be made on GlobalFoundries 22FDX 22 nanometer semiconductor process. This development can also help significantly for scaling up the qubit count because these CMOS transistors can help drastically reduce the number of control lines that need to be fed through the refrigerator. Routing these control lines is a major headaches for hardware engineers. and is another potential limiter in how many qubits can fit inside the fridge.
Diraq’s integration of silicon qubits with standard CMOS transistors aims to push qubit numbers on a chip to the million mark, paving the way for commercially viable quantum computing. The company’s technology leverages decades of semiconductor foundry advancements, aiming to revolutionize applications in drug discovery, optimization, cryptography, and beyond.
For more on these announcements, you can view a press release posted on the Diraq website here.
June 13, 2024