The ambition of QUENOT is to overcome several current conceptual and experimental limits in nanooptics using the quantum properties of fast electrons. Indeed, certain key concepts and quantities in nanooptics (super-chirality, spatial coherence of excitations in optical nanostructures and quantum optics of photonic excitations) have been very sparsely studied at their relevant scale: the sub-wavelength scale.
Super-chirality, that is to say, the increase of the chiral properties of light beyond those reached by purely circularly polarized light, can be observed theoretically in the vicinity of chiral nanostructures. The nanoscale mapping of super-chirality, which has never been done before, would allow the development of new biological sensors with greatly increased enantiomeric selectivity, with obvious implications in the pharmaceutical industry. Spatial coherence of confined excitations such as surface plasmons can be quantified through a quantity called cross-electromagnetic density (CDOS). The latter has at the moment been measured only in a narrow spectral range. Its measurement at the nanoscale and over a wide spectral range would shed light on the spatial coherence of excitations such as surface plasmons in random films, the nature of which remains controversial in the community. Finally, if the study of single photon emitters coupled to cavities has already been carried out, the study of quantum properties (creation and manipulation of Fock states) of nanostructured cavities (like cavities in photon gap materials) has never been considered theoretically or experimentally and would represent a major breakthrough in the field of quantum nanooptics.
The use of fast electrons (about half the speed of light) as provided by Transmission Electron Microscopy (TEM) has been an impressive success over the last 15 years for the study of nanooptics at scales much smaller than the visible and infra-red wavelengths. The consortium members have been instrumental in this success. However, the study of the physical properties mentioned above is largely considered as unachievable by TEM techniques. The founding idea of QUENOT is that the quantum properties of fast electrons, long thought to be difficult to manipulate from a theoretical and experimental point of view, make it possible to retrieve, at the nanoscale, the measurement of super-chirality, CDOS, as well as the preparation and measurement of Fock states in photonic nanostructures.
We intend to lift these conceptual and technical locks through a consortium combining theoretical and experimental expertises in nano-optics, advanced nanofabrication and instrumentation in electronic optics. Although the challenge is important, a number of very recent advances in the field, as well as preliminary theoretical and experimental studies, support us in the idea that it can be raised now and specifically by our consortium.
QUENOT should keep France at the forefront of nanoptic research with fast electrons; in addition, the culture of some members of the consortium to provide access to their experiments will make these advances directly available to the community. QUENOT should impact the above-mentioned nanooptic fields. Beyond this, all the methods and concepts developed in this context can be directly used in the more general context of condensed matter, with for example the measurement of magnetic dichroism at the atomic scale or the measurement of coherence length of phonons.
Project coordinator
Mathieu Kociak
Partners:
ANR funding
703 k€
Beginning and duration of the scientific project
October 2021 – 42 Months