The field of Quantum Technologies aims at designing applications of the concept of Quantum Superpositions (such as entanglement), known as the second quantum revolution. By manipulating single quantum systems such as atoms, ions or photons, one will be able to benefit from their quantum behavior to achieve information processing and communication well beyond the limits of what is possible with classical physics. In the long term, this field is expected to provide disruptive technologies with a strong societal impact, such as a secure worldwide communication network and the development of quantum internet, computers and simulators that will outperform classical computers.
The LIMQUET project, which stands for Light-Matter Interfaces for Quantum Enhanced Technologies, is composed of a network of seven academic and three industrial partner organisations from five different countries in Europe. The LIMQUET project focusses on the interaction of light with atoms, ions and nanostructures and light with light as central tools in the development of new quantum technologies. Examples are quantum memories and quantum networks, which rely on the transfer of optical information, via single photons as its smallest constituents, into and out of atomic or optical memories. Another elementary constituent in quantum information technology is quantum logical gates.
Confinement of light strongly coupled to atoms can be achieved between highly reflective mirrors forming a cavity (corresponding to the field of cavity quantum electrodynamics, cQED). An alternative approach uses optically very dense samples, e.g. cold atoms prepared in a micro-trap. This enables strong non-linear couplings to store information contained in light pulses, and hence to provide an optical memory or to induce effective interactions between single photons for producing optical quantum gate and single photon quantum filter. The third approach uses metallic nano-structures and nano-optics, merging integrated optics and cQED principles via quantum plasmonics (representing quantized collective oscillations of the electrons of the metal in interaction with the electromagnetic field).
Via the training of 18 Early-Stage-Researchers, the LIMQUET project promoted collaborations between teams of quantum and nano-optics to combine the approaches towards the realisation of strong coupling between single quantum emitters and single photons in nanostructures. To achieve this goal, processes and techniques originating from atoms and ions research with optical cavities have been adapted to light-matter interactions with nanostructures, providing a critical step towards the development of powerful quantum devices.
Different approaches to provide the highly efficient light-matter interfaces have been successfully implemented: strong coupling between light and matter, controlled production of single photons, efficient memories, and miniaturization of the processes at the nanoscale.
