Superconducting technologies are prime candidates to ripen quantum effects into devices and applications. The accumulated knowledge in decades of work in understanding superconductivity allows scientists now to make experiments by design, controlling relevant parameters in devices. A new field is emerging whose final objective is to improve appliances taking advantage of quantum effects, be it for dissipationless transport of current, generation of high magnetic fields, sensors or quantum information. Quantum behavior is controlled by using hybrids of superconductors with magnets, insulators, semiconductors or normal metals. The field will impact crucial areas for societal development, including energy, transport, medicine or computation. The scientific and technical communities working in superconductivity, whose activities put Europe at the frontier of research, are traditionally small groups working independently. Nanocohybri addresses the pressing need for a common place to share knowledge and infrastructure and develop new cooperative projects. TheAction started in November 2017 and will last until October 2021 and provides numerous funding opportunities, particularly for young students and postdocs all over Europe. Currently, 27 countries have joined the network.

See the webpage for all details, including the Management Committee.

Project funded by COST program of the European Union.

Superconductivity is a relevant player in the emerging field of quantum technologies, whose final objective is to bring quantum effects into appliances. Superconducting applications, be it levitating trains or quantum computers, produce a considerable fascination and are counterintuitive. The consequences of quantum coherence in superconductors brings forward spectacular effects, which often serve to show the weirdness of quantum mechanics to both the general public and to engineers. Superconducting applications develop steadily and we can expect a quantum leap in the societal impact of superconductivity during the coming decades through current carrying applications as well as novel quantum technologies. Many recently discovered superconductors are quantum materials, a term that groups quantum behavior observed in several systems, whose weird properties are far from being fully exploited and often yet to be understood. However, it is clear that these properties potentially provide unique technological advances, such as topologically protected quantum states or the simplification of quantum computers required to ripen this technology into wide use. To find these properties in quantum materials, we need to tune materials to a “sweet spot” modifying magnetic field, charge or strain. Often, this “sweet spot” is located at a quantum phase transition, in between competing orders. Traditionally, methods to study quantum materials have been however restrained to a particular system at a given location in proximity to the quantum phase transition. This is particularly true for one of the most powerful techniques, very low temperature scanning tunneling microscopy (STM). STM is used to measure the bandstructure, superconducting properties such as gap or Josephson effect and their spatial dependence (vortex lattices). A large deal of understanding has been achieved, showing the power of STM. However, there is a pressing need to tune quantum materials precisely into the state that shows most interesting properties. Within this project, we attack this problem and study STM in new materials relevant to quantum technologies by controlling their quantum state.

Project FIS2017-84330-R co-directed with I. Guillamón and funded by the Spanish State Research Agency, AEI.

Superconductors continue to be the most versatile and technologically relevant macroscopic quantum coherent systems. Any local perturbation of the superconducting state, such as a Josephson weak link, a vortex or a magnetic impurity, leads to the creation of bound quasiparticle states that are linked to the condensate through Andreev reflection. Andreev bound states have been observed in many systems through tunneling spectroscopy at length scales of order of the superconducting coherence length. These are mesoscopic quantum states whose energy can be, in principle, modified by means of gate electrodes or by an external magnetic field. Using Andreev states located in different places one could also generate non-local quantum entangled states. For instance, the much discussed topologically protected Majorana fermions proposed for quantum computation are nothing but zero energy excitations in topological superconductors which have a similar origin as Andreev bound states. Understanding and controlling Andreev states at a microscopic level is therefore of crucial importance for the progress of this potential technology. The project aims to address the interaction between Andreev levels and their surrounding by obtaining vivid images of the quasiparticle states at length scales from the superconducting coherence length down to the Fermi wavelength. In parallel, we will make a realistic model of these experiments. We will include details of their microscopic electronic structure which were so far left out from the mostly phenomenological approaches used to interpret experimental data. IFIMAC will benefit from the integration of theory with the available infrastructure for millikelvin tunneling microscopy, establishing the sought internal dialogue among theory and experiment.

Project co-directed with Alfredo Levy Yeyati. Project funded by the María de Maeztu program, at IFIMAC.