Cryogenic programmable circuit frontends for resonant cavities aiming quantum-coherence links for quantum computing cores

Abstract

Quantum computing is envisioned as a potential revolution that could solve particular problems that classical computers can't solve. While there's a lot of research in algorithms for quantum computing, the current limitations in the development of this technology lies in the hardware and the physical implementation. The basic unit of information, the qubit, is extremely sensitive to crosstalk, electromagnetic radiations and thermal excitation. Nowadays, only a few hundred useful qubits have been built on a chip, yet thousands or even millions are required to beat classical computers. Apart from qubits, quantum computers require extra circuitry such as control and readout electronics. Resonators that show a high quality factor are known as excellent candidates to perform qubit measurements. Moreover, their nature indicates they could act as quantum buses and quantum memories. However, they take a large area and are built with expensive technologies and show a very limited configurability. In this work, a 22-nm FDSOI CMOS tunnable resonator is proposed, to operate at cryogenic temperatures. The physical principles that are presented and derived show how this resonator can be configured to read an array of qubits in a multiplexed fashion. The design maximizes quality factor and tunable frequency range. As future works, the fact that the resonance frequency is modifiable means this design could be used to coherently move information between distant qubits.