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 2020

In 2020, the QCT group achieved the complete construction of its laboratory at the IFAE workshop. This involved a complete re-structuring of an area in the workshop that was fitted by sound-proof, nonmagnetic walls, anti-static flooring, and new utility access such as compressed air, chilled water, nitrogen and an isolation transformer to provide noise-free electrical power to the laboratory. The accommodation of the space was followed by the installation of two dilution refrigerators with capacity to attain temperatures in the 10-20 millikelvin range, necessary to carry out the experiments with superconducting qubits used by the QCT group.
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The group tripled the number of members (from 2PhDs to 5PhDs and one postdoc) during 2020 thanks to the funds received during 2019 and 2020. In addition, the group was awarded two scholarships from the program ‘Doctorats Industrials’ for two employees of the IFAE spin-off Qilimanjaro. All the new group members started to contribute to the overall group goal to study and develop technology for quantum coherent annealers. The first of the experiments was started at the end of 2020 and a preprint already was produced in January 2021.

QCT group to coordinate proposal AVaQus from the FET Open program

Summary of activities:

  • Using one of the new refrigerators, performed measurements with a single superconducting qubit to complete the demonstration of the implementation of the universal approximant quantum algorithm.
  • Dr. Forn-Díaz was awarded a FET Open project for the proposal AVaQus: Annealing-based Variational Quantum processors, which aims to develop coherent quantum annealers in the next three years together with another five academic institutions in Europe and three startup companies.
  • The QCT group was completed with the hiring of 3 PhD students (one for the FET Open project, another for the Quantera project SiUCs, and a third one awarded an InPhinit scholarship from the La Caixa Foundation) and one postdoc (for the FET Open project).

First superconducting qubit measured at IFAE

The new laboratory was already used to complete the first complete work performed at IFAE, the demonstration of a single qubit as a universal approximant. This new quantum algorithm was deviced by the group led by Prof. J. I. Latorre, currently the director of the Center for Quantum Technologies in Singapore, and was implemented using the single superconducting qubit device that was fabricated by the group of Prof. Martin Weides at the Karlsruhe Institute of Technology. The initial round of measurements had been performed at the Catalan Institute of Nanoscience and Nanotechnology (ICN2) in the lab of Prof. S. O. Valenzuela while the IFAE laboratory was being built. This quantum algorithm uses the qubit properties to approximate the value of any bounded mathematical function after a series of quantum gates applied to the qubit. The experimental demonstration showed full agreement with the simulated values. A preprint was produced in early 2021.