For the first time, control electronics can be placed within a whisker of spin qubits without frying their quantum state, all thanks to a new ultra-low power chip that runs at cryogenic temperatures.
This custom CMOS chip can operate less than a millimetre from qubits at just under 1 kelvin, all while consuming a tiny 10 microwatts of power. That sort of thermal restraint is crucial when dealing with quantum bits, which need to sit just above absolute zero to preserve their so-called “coherence”.
Lead researcher David Reilly, professor at the University of Sydney Nano Institute, said, “This result has been more than a decade in the making, building up the know-how to design electronic systems that dissipate tiny amounts of power and operate near absolute zero.”
This “proof of principle” could lead to quantum processors that integrate classical control and millions of qubits onto a single device, a significant milestone toward actually scaling the tech beyond lab curiosities.
Spin qubits, the type used here, encode information in the spin of electrons and are popular among researchers because they can be made using the same CMOS processes found in everyday smartphones. This means they are not just efficient but potentially cheap to manufacture, sliding neatly into existing chipmaking infrastructure.
Unlike superconducting, photonic or trapped-ion qubits, spin qubits bring scalability to the table without needing a whole new fab to make them. The sticking point has been the electronics needed to read and control them, which have traditionally added too much heat and noise to sit near the qubits.
Senior hardware engineer at Emergence Quantum and the designer of the chip, Kushal Das, said, “Now that we have shown that milli-kelvin control does not degrade the performance of single- and two-qubit quantum gates, we expect many will follow our lead.”
Tests showed that gate operations remained stable, accurate and coherent even with the control chip less than a millimetre away. The analogue sections, responsible for pulsing the qubits, consumed a staggeringly low 20 nanowatts per megahertz.
Reilly believes this changes the game. “This will take us from the realm of quantum computers being fascinating laboratory machines to the stage where we can start discovering the real-world problems that these devices can solve for humanity,” he said.
There is also the promise of more immediate uses. Beyond quantum computing, Reilly sees spin qubits and cryo-electronics playing a role in future sensing systems and potentially even data centre design.
CMOS-compatible quantum chips with integrated control may well be the nudge that turns quantum computing from nearly there to actually useful. The question now is who else can pull off such precision engineering with barely a whisper of heat.
