Experiments

Single emitters for quantum technologies

By combining advanced photonic materials with single organic molecules, we seek for novel light-matter interfaces for quantum technologies, where strong non-linearities are often needed.
The experimental research activity on organic molecules for quantum optics at LENS was launched in 2012, when the group PI moved from ETH in Zuerich to Florence. It represents an interdisciplinary effort, involving contributions from the area of photonics and that of atomic and molecular physics. During the last two years we developed and fully characterizedan organic-molecule based source of indistinguishable single photons. Our emitters can be very easily manipulated in the solid state and, at liquid helium temperatures, dephasing of the transition dipole due to phonon-coupling vanishes and emission becomes life-time limited. In particular we study Dibenzoterrylene (DBT) molecules embedded in thin (≈ 50 nm) crystalline films of anthracene. The developed fabrication scheme allows for integration with semiconductor membranes, as well as plasmonic nanostructures, or graphene devices.We also proved a-posteriori nanopositioning by AFM nano-manipulation.

Single-molecule-based photon sources were selectively coupled to the evanescent electromagnetic field of surface plasmons, observing strong coupling in the dispersion relation of such hybrid emitter.
We studied the problem of a single emitter in close proximity to a graphene monolayer and verified the universal d^-4 dependence of the energy transfer efficiency between the molecular dipole and the two-dimensional medium. A first proof of principle for a graphene-based nanoposition sensor was then set.
In collaboration with F. Koppens group at ICFO, we have been working on the implementation of a quantum nanoposition sensor, based on the measurement of a frequency shift of the molecule resonance due to the Casimir effect exerted by a graphene suspended membrane.
We have designed a plasmonic coupler, which will allow to integrate our emitter/non-linear element into optical circuits. In collaboration with the group of O. Benson at the Humboldt University in Berlin, we have fabricated and characterized such hybrid dielectric-plasmonic coupler.

summary of our research activities