“We’d like to bring our expertise in low-power classical computing to a new and exciting domain, namely to efficiently provide control, error correction, and other key functions for emerging quantum computers,” said Dennis Sylvester, Edward S. Davidson Collegiate Professor of Electrical and Computer Engineering (ECE).
Quantum computing is seen as having the potential to exponentially increase the ability to model complex simulations, which could help to revolutionise a whole range of different industries including drug development, financial risk profiling, supply chain optimisation, among others. However, quantum computing will require significant improvements in the efficiency and reliability of existing technology.
Qubits, the essential units for quantum computing, are typically kept at temperatures near absolute zero, generally around 4 K (-269.15 °C; -452.47 °F). Conversely, the control electronics for the computer operate at room temperature, requiring the cryogenic qubits to be kept at a distance and wired out to the other components of the computer. This arrangement drastically decreases efficiency, increases energy consumption, restricts computing power, and limits the practical uses of quantum computers.
Sylvester and ECE PhD student Qirui Zhang are working to design control electronics that can be used at the frigid temperatures qubits require. However, redesigning the silicon chips and simulating their performance in cryogenic conditions requires substantial time, effort, and funds - prior to building the control electronics.
Consequently, the team is looking to fast-track the development of cryogenic control electronics by partnering with Semiwise.
Semiwise, a startup spinoff from The University of Glasgow by Prof. Asen Asenov, has developed a set of Process Design Kit (PDK) strength of SPICE (i.e., simulation program with integrated circuit emphasis) models suitable for cryogenic circuit design.
The models, based on Globalfoundries 22FDX PDK, are derived using a patented methodology that combine cryogenic transistor measurements with Technology Computer Aided Design (TCAD) simulations.
The PDK includes corners and statistics and is consistent with the post-layout verification requirements.
“Taking standard CMOS down to 4K or -270°C is a major step into new territory where the operating characteristics of the transistors change markedly,” said Asenov, “The cryogenic chip design will not only unleash the power of quantum computers but could also increase significantly the energy efficiency of the data centres in the transition to a net zero economy.”
“Everything’s new and unknown,” said Zhang. “We are building up the methodology for how to use the superconducting qubits. Our first priority is quality and robustness to maximise the fidelity of controlling that qubit and minimize any potential corruption to the qubit state.”
The next steps for the team include using the SPICE models to build cryogenic control systems from the ground up.
