QUANTUm METamaterials wit High Tc Superconductors – QUANTUMET

Information and Communications Technologies (ICT) aim at processing and exchanging information by means of electromagnetic waves and electrical currents. For a long time, engineers and researchers have been using materials given by Nature to implement these processes, emit and receive waves and signals. In the recent years "meta-materials" have been developed with new properties such as negative refraction index, to create very interesting functionalities. Among them, arrays of Split Ring Resonators (SRR) have been intensively studied since they present a negative permeability in the vicinity of their resonances. To limit the losses which impair the properties, superconductors appear as ideal candidates, at least up to their cut-off frequency. In addition, they present a natural tunability, since their inductance (and therefore the resonance frequency) can be changed with the temperature. These very interesting properties take place at very low temperature (4K), which make them difficult to use at a large scale.
The Singaporean partner of this project was the first to use High Tc Superconductors (HTSc) working at 77 k to make tunable meta-materials, with temperature or ultra-short optical pulses. He also studied non linear behaviors that appear for high THz power. Meanwhile, the French partner developed a new technology to make with these materials Josephson Junctions (JJ) and SQUIDs (Superconducting Quantum Interference Device), whose inductance can be easily tuned by a weak magnetic field. It developed heterodyne detector working at 400 GHz and beyond, and SQIFs (Superconducting Interference Filter) for radar amplifiers. These two leaders in their field gather to propose a new concept : HTSc meta-materials tunable with a magnetic field, working in the THz domain. Since there are also needs of such meta-materials for RF frequencies, there will also study them in the GHz range. For this, they will develop a new version of the ion-irradiation technology to make more controlled JJ with a He Focused Ion Beam (FIB).
The work is divided in 4 technical Workpackages : (i) the realization of HTSc SRR with the ion irradiation technology (ii) the development of tunable SRR with DC-SQUIDs at GHz and THz frequencies (iii) the development of tunable SRR with RF-SQUIDs at GHz and THz frequencies (iv) the development of He FIB technology to make JJ.
This work paves the way for new functionalities. Indeed, one can control the meta-material locally (through a local magnetic field generated by a current wire) and draw patterns of indexes. Moreover, ion irradiation technology can be used to make complex superconducting circuits with mixer, non linear elements to make on-chip signal processing.