Quantum Computing Technologies

Pol Forn-Díaz

The QCT group develops superconducting circuits for applications in quantum computation. By employing Josephson-junction technology, the group engineers superconducting qubits for the implementetion of quantum algorithms. Part of the research is focused on improving the qubit quality by mitigation of environmental noise sources, while at the same time the circuits are used to investigate fundamental physics of quantum optics phenomena.

Activities in 2021

In 2021, the QCT group at IFAE began device production in-house. This was due to the installation of a metal evaporator inside the IFAE cleanroom. This evaporator, owned by Qilimanjaro Quantum Tech S.L., a spin-off from IFAE, is a key differential element to produce aluminum-only circuits with Josephson junctions of the highest quality. This installation was followed by the beginning of operations in the nearby cleanroom at the Institute of Microelectronics of Barcelona (IMB-CNM-CSIC), to produce the first generation of superconducting devices using optical and electron-beam lithography techniques. Further additions to the IFAE cleanroom include a fumehood for performing lift-off process after evaporation and a new optical microscope to inspect devices after lift-off. Altogether has led to the first Josephson junctions being fabricated at IFAE, with the first functional qubits being produced together with the Qilimanjaro Quantum Tech team.

A new member joined the group, Dr. Elia Bertoldo, being the first postdoctoral researcher, having experience in underground cryogenics experiments at the Max Plank Institute.

A long-term collaboration with the Underground Laboratory at Canfranc (LSC) was started formally in 2021. First, by providing assessment on the acquisition of a future dilution refrigerator by LSC that will serve as qubit measurement station, among other types of experiments at cryogenic temperatures. Second, a first qubit experiment was prepared using the existing cryostat of the CROSS experiment, a long-term project to develop a neutrinoless double-beta decay. This qubit measurement setup has not been yet used due to lack of a qubit, but is expected in 2022.

A collaboration was started with IMB-CNM-CSIC for the development of a new type of superconducting material, aluminum nitride. This material has not been used as a superconductor, and, if confirmed of its existence, would contribute interesting properties, such as potential lack of aluminum oxide and a high kinetic inductance. Within this collaboration, the material will be produced by CNM and devices will be characterized at the QCT lab.

The AVaQus project passed its mid-term review, 12 months after its start. The review consisted of a virtual call with all PIs of the AVaQus project, with 3 reviewers plus the project officer, Tiziana Campana. The review lasted an entire day, with presentations by each work package leader (IFAE leads WP1 and WP3, while the University of Glasgow leads WP2 and CSIC leads WP4). This is the first of two review procedures, the next one to be held at the end of the project in the spring of 2024. The reviewers considered the project to be evolving very well, with some points to be corrected.