SuPErConducTing Radio-frequency switch for qUantuM technologies (Spectrum)

Research Project, 2022 – 2025

Despite the high expectations and numerous announcements that have been made over the past ten years, the spread of Quantum Computers (QCs) is still in its infancy. The major factors limiting the diffusion and market penetration of QCs are their low scalability and high cost. Both issues are connected to the bulkiness and complexity of the signal lines that operate the QC. The required large amount of cables undermine the scalability and decrease the thermal stability of the Quantum Processing Units (QPUs). With this project, we aim to increase the scalability and reduce the thermal issues of QPU developing a radiofrequency (RF) switch, QueSt, that allow to simultaneously control the state of multiple qubits through the same cable. QueSt goes well beyond what is achieved with state-of-the-art electronics that typically provide bulky, slowly and energy inefficient solutions. The core component of QueSt is an all-metallic superconducting transistor-controlled via gate voltages. This transistor exploits the peculiar characteristics of a superconducting material to work at frequencies (~1 THz) unachievable with classical semiconductor electronic components and with nearly zero power dissipation.
During SPECTRUM we are going to build a complete test platform QueSt devices. The state-of-the-art nanofabricated prototype of QueSt will be tested in a custom made cryostat able to unleash the true potential of this technology. Furthermore, ultra-fast FPGA-based electronics will take the case of the control of multiple switches, providing an affordable and performant control over the prototype. This platform will be the environment in which QueSt will be studied at strict contact with the state of the art Quantum Processing Units. The experiments performed in real Quantum Computer under the EU-funded Spectrum project will be the first step to the true Quantum Revolution.