The THz range is a “boundary” region where the classical electronics or photonics technologies fail and new solutions must be proposed to realize devices and components like power sources, detectors and interconnects. This difficulty has meant that the THz range has only begun to be explored thoroughly over the last decade. For instance, to realize THz emitters some classical high-frequency electronic devices have been coupled to quantum generators of coherent light, to obtain a large variety of devices based on free electron accelerators, intense laser-based sources, superconducting Josephson-junction, nanoscale quantum cascade lasers and exciton-polariton systems. Notably, all these emitters have been shown to be unfit for practical application and commercial use, leading to the conclusion that the solutions for bridging the THz gap must stem from completely new ideas. 

Formulating and developing these new ideas is a main goal of our international inter-disciplinary project.

A promising route to the THz technology has recently been opened by the impressive progress of nanotechnology, which has led to the synthesis and fabrication of different nanostructured materials with fascinating mechanical, electronic and optical properties irreducible to that of classical bulk materials. The nanotechnology led to the blurring of the classical boundary between electronics and photonics, with cross-fertilization of their concepts.

What we have seen for the future?

Quantum effects (e.g., dipole-dipole, spin-spin, spin-orbital interactions, tunneling) on nanostructured low-dimensional materials are widely proposed to realize nanoscale antennas and sensing elements. Many special quantum mechanisms for feeding nano-antennas have been so far investigated: superradiance and correlated spontaneous emission, or solitons and breather’s. To this end, mesoscopic structures as quantum dots open a way for the efficient control and feeding of nano-antennas in the infrared and optical frequency ranges, in strong- and super-strong coupling regimes.

The main difference between nanodevices and their macroscopic analogues is the importance of specific quantum interactions along with the classical electromagnetic coupling. Such interactions give rise, for instance, to phenomena like quantum entanglement, which can be regarded not only as an important tool of quantum control, but also as a mechanism of unwanted parasitic coupling between rather distant elements, which is able to break down the normal working regimes of nanodevices. Indeed, the partners of this project recently formulated the general concept of Electromagnetic Compatibility at nanoscale, nano-EMC, to take into account the above mechanisms, alongside with classical electromagnetic coupling.

What we see here is the possibility of realizing THz devices by exploiting new promising physical mechanisms enabling the excitation of mesoscopic structures via shot noise, Rabi and Rabi-Bloch oscillations, and direct interband THz transitions induced by optical excitation. 

Several types of nanostructured materials will be investigated, such as graphene nanoribbons and graphene/polymer sandwiches, with embedded mesoscopic structures, or atomic chains (e.g., transition metals dichalcogenides and graphene dots and their chains) with interatomic coupling.

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