Quantum Computing Technologies

Pol Forn-Díaz

The Quantum Computing Technology (QCT) group develops superconducting quantum circuits for applications in quantum computation and quantum science. By engineering superconducting devices with a controllable quantum state, the QCT group can implement a variety of quantum protocols: quantum algorithms to solve complex mathematical problems, simulation of light-matter interaction models, and study the interaction of high energy particles and radiation with superconducting films. The superconducting qubit state control is achieved by operating at cryogenic temperatures.

Activities in 2019

The QCT group was established in May 2019 when Dr. Pol Forn-Díaz joined IFAE as a junior group leader researcher. In the time since the creation of the group, several key tasks to initiate the group activities have been carried out:

  1. Hiring of first PhD students and undergraduates
  2. Beginning plan for laboratory construction at IFAE’s workshop to start in January 2020 and expected to be completed by April 2020.
  3. Launched public tender at the European Official Journal to acquire a dilution refrigerator to be installed at IFAE’s workshop by June 2020.
  4. Dr. Manel Martínez, from the IFAE Gamma Ray astronomy group, joined the QCT group to contribute with his technical expertise.

The main scientific activity is the continuation of the collaboration with Prof. S. O. Valenzuela’s group at the Catalan Institute of Nanoscience and Nanotechnology (ICN2), which was initiated prior to the time Dr. Forn-Diaz joined IFAE. In this collaboration, an ongoing experiment has been running during 2019 with the aim of controlling a single superconducting quantum bit inside the dilution refrigerator, a cryostat with a base temperature of 0.01 degrees above absolute zero.

Figure 1: TBD
Figure 2: TBD
Figure 3: TBD

Observation of coherent oscillations of a driven superconducting qubit

The most important achievement of the QCT group in 2019 was the observation of coherent oscillations (also known as Rabi oscillations) of a driven superconducting qubit. This achievement represents a very important milestone for the group, as it demonstrates the capability to coherently control the state of the superconducting qubit at will, and opened the door to implement the first one-qubit quantum algorithms that have been developed by the collaborating group at the University of Barcelona led by Prof. J. I. Latorre.
Figure 4: TBD

The observation of Rabi oscillations certifies the group as the first in Spain to achieve coherent control of a quantum system

The observation of Rabi oscillations certifies the group as the first in Spain to achieve coherent control of a quantum system that is necessary to implement quantum computing protocols. The experiment was performed at the laboratory of Prof. S. O. Valenzuela at the Catalan Institute of Nanoscience and Nanotechnology (ICN2), which is a collaborator of the QCT group. The superconducting qubit is a three-dimensional transmon-type circuit and it was designed and fabricated at the Karlsruhe Institute of Technology (KIT) by the group of Prof. Martin Weides, a collaborator of the QCT group. The experiment consists of a single superconducting qubit confined inside a superconducting aluminum cavity that is used to read out the qubit state. The whole system is anchored to the lowest temperature stage of a dilution refrigerator at a temperature of 20 millikelvins (0.02 K). External microwave pulses are generated by room temperature radio frequency equipment and sent to the qubit with specialized coaxial cables that deliver the signal with low degradation.