Cryo-CMOS Electrical Interfaces for Large-Scale Quantum Computers

Quantum computers promise to ignite the next technological revolution as the classical computer did for last century’s digital revolution by efficiently solving problems that are intractable by today’s computers. By enabling the efficient simulation of quantum systems, quantum computing will allow both the optimization of existing industrial processes and the synthesis of new drugs and materials, thus representing an unprecedented game changer with the potential to disrupt entire industries, create new ones, and radically change our lives. Quantum computers rely on processing the information stored in quantum bits (qubits). Although such qubits typically require cryogenic operation, today’s quantum processors are mainly controlled by conventional electronics at room temperature. A few wires can readily bridge this thermal gap since today’s quantum computers employ only a few qubits. However, practical quantum computers addressing relevant problems will require more than thousands of qubits, making this approach impractical. A more scalable approach consists in operating a complex electronic interface at cryogenic temperature, very close to the quantum processor, eventually in the same package or even on the same chip. By exploiting the advances in performance and integration offered by the semiconductor industry, CMOS operating at cryogenic temperature (cryo-CMOS) is the most viable technology for such a cryogenic interface. In this talk, we will quickly review the basics of quantum computation and briefly overview state-of-the-art quantum computers and the open challenges towards a practical computing device. After showing the behavior of CMOS devices at cryogenic temperature, we will go over several cryo-CMOS circuits for both qubit drive and readout, and their verification with real-world qubits, focusing on the latest results and highlighting challenges and opportunities.