Google Builds Circuit to Solve One of Quantum Computing’s Biggest Problems

One of the big limiters to today’s quantum computing systems is that while their superconducting qubits live in a cryogenic enclosure at less than 1 kelvin, all the control and readout circuits must be at room temperature. For today’s sub-100-qubit systems, there’s enough space for specialized RF cabling to come in and out of the enclosure. But to scale up to the million-qubit systems needed to do really cool stuff, there just won’t be enough room.

So quantum computer engineers want to bring some of those electronics inside the cryogenic fridge. In a first step, researchers at Google, the University of Massachusetts at Amherst, and the University of California Santa Barbara reported making a key control circuit in CMOS that will work at cryogenic temperatures. The circuit they described at the IEEE International Solid-State Circuits Conference in San Francisco last month is a high-performance, low-power pulse modulator needed to program the qubits. It is the first disclosed instance of a CMOS cryogenic quantum control IC interacting with real qubits.