QUANLUX is a project funded by the EU program Horizon 2020 through the Marie Skłodowska-Curie Actions Individual Fellowship under grant agreement No.882536.
The Project aims to theoretically propose a novel light-matter interface consisting of ordered atomic arrays as an ideal platform to implement Quantum Nonlinear Optics (QNLO) processes.
Quantum Nonlinear Optics
Nonlinear optical processes constitute the basis of many applications in modern science and engineering, where an effective interaction between electromagnetic signals inside some medium is often required. These processes usually occur at high light intensities, but over the years, many efforts have been invested to progressively reduce the minimum required input power. The ultimate goal is to achieve the realm of Quantum Nonlinear Optics (QNLO) where nonlinear effects occur at the level of individual photons. Achieving such a regime would allow the generation and manipulation of non-classical states of light and would open exciting new scenarios involving quantum many-body physics of light. Unfortunately, photons do not like talking to each other, that's why many light-matter interfaces have been proposed over the years to reach this goal.
State of the art
The basic physics behind quantum nonlinear effects can be understood by observing that an
individual atom, for practical purposes, can be viewed as a two-level system from the standpoint of light, unable
to emit nor absorb more than a single photon at a time. Despite this natural "huge" nonlinearity, the bottleneck
lies in the low interaction probability between single atoms and photons in free space. To overcome this natural
“deficiency” several approaches have been pursued along the years involving the confinement of light in
nanophotonics structures, e.g. cavities, waveguides, etc., or large ensembles of Rydberg atoms where the QNLO
response relies on the strong interaction between high-lying Rydberg levels. Over the years both approaches have reached great achievements toward the implementation of QNLO processes. However, such processes still suffer from high infidelities or photon losses, and finding a robust route remains an outstanding challenge.
A new way forward: QNLO with atomic arrays.
Recently a new approach to overcome this limitation has emerged proposing to exploit the potential power of harnessing wave interference, which is neglected in standard “textbook” treatments that assume an incoherent emission of light. Indeed, while such an assumption is valid in low-density disordered media, it gets challenged in sub-wavelength ordered atomic arrays.
In this scenario, it has recently been observed that wave interference can indeed cause a collective response of the
atoms with the formation of guided sub-radiant collective atomic states. QUANLUX aims to exploit the unexplored potential of ordered atomic arrays to develop an
ideal platform for QNLO processes. The goal is to use
the collective response of the array to improve the QNLO performance compared to usual platforms.
