Cavity control of Excitons in two dimensional Materials

We propose a robust and efficient way of controlling the optical spectra of two-dimensional materials and van der Waals heterostructures by quantum cavity embedding. The cavity light-matter coupling leads to the formation of exciton-polaritons, a superposition of photons and excitons. Our first principles study demonstrates a reordering and mixing of bright and dark excitons spectral features and in the case of a type II van-der-Waals heterostructure an inversion of intra and interlayer excitonic resonances. We further show that the cavity light-matter coupling strongly depends on the dielectric environment and can be controlled by encapsulating the active 2D crystal in another dielectric material. Our theoretical calculations are based on a newly developed non-perturbative many-body framework to solve the coupled electron-photon Schr\"odinger equation in a quantum-electrodynamical extension of the Bethe-Salpeter approach. This approach enables the ab-initio simulations of exciton-polariton states and their dispersion from weak to strong cavity light-matter coupling regimes. Our method is then extended to treat van der Waals heterostructures and encapsulated 2D materials using a simplified Mott-Wannier description of the excitons that can be applied to very large systems beyond reach for fully ab-initio approaches.Comment: 32 pages. 10 figures, 2 tabl

Experimental optimal cloning of four-dimensional quantum states of photons

Optimal quantum cloning is the process of making one or more copies of an arbitrary unknown input quantum state with the highest possible fidelity. All reported demonstrations of quantum cloning have so far been limited to copying two-dimensional quantum states, or qubits. We report the experimental realization of the optimal quantum cloning of four-dimensional quantum states, or ququarts, encoded in the polarization and orbital angular momentum degrees of freedom of photons. Our procedure, based on the symmetrization method, is also shown to be generally applicable to quantum states of arbitrarily high dimension -- or qudits -- and to be scalable to an arbitrary number of copies, in all cases remaining optimal. Furthermore, we report the bosonic coalescence of two single-particle entangled states.Comment: 5 pages, 3 figure

What do Italian consumers know about Economic Data? An analysis based on the ISTAT Consumers Survey

Standard theory describes economic decisions as the result of optimising behaviour of well-informed economic agents. However, whether citizens are really well informed on economic data is still highly disputed. In order to investigate on this issue, since 2007 the Italian Consumers survey has incorporated a number of questions on the degree of knowledge about economic data. Surveys results show that the level of knowledge of Italian consumers is relatively low; moreover, knowledge seems to significantly vary across different groups of respondents, depending on individual characteristics and the perceived costs and benefits of acquiring information. Results provide evidence of deviation from the standard approach of full rationality in the information acquisition process: if agents are not always fully rational, delays in information acquisition should be taken into account by policy makers in designing appropriate interventions

What do Italian consumers know about Economic Data? An analysis based on the ISTAT Consumers Survey

Standard theory describes economic decisions as the result of optimising behaviour of well-informed economic agents. However, whether citizens are really well informed on economic data is still highly disputed. In order to investigate on this issue, since 2007 the Italian Consumers survey has incorporated a number of questions on the degree of knowledge about economic data. Surveys results show that the level of knowledge of Italian consumers is relatively low; moreover, knowledge seems to significantly vary across different groups of respondents, depending on individual characteristics and the perceived costs and benefits of acquiring information. Results provide evidence of deviation from the standard approach of full rationality in the information acquisition process: if agents are not always fully rational, delays in information acquisition should be taken into account by policy makers in designing appropriate interventions

Improving Knot Segmentation Using Deep Learning Techniques

In the context of Computed Tomography scanning of logs, accurate detection of knots is key for delivering a successful product. Reliable detection of knots in the sapwood is hard with traditional computer vision techniques, because of the different density conditions between sapwood and heartwood. The advancements provided by deep learning in the field of semantic image segmentation kick-started a new way of approaching such problems: deep neural networks can be trained on large amounts of labelled data and successfully employed in production environments to improve the performances on knot detection. Adapting state-of-the-art network architectures and using more than 10.000 labelled knots from pine and spruce logs, we were able to develop a new two-step approach for identifying knots in CT scans of logs with unprecedented accuracy while at the same time satisfying the time constraints that a real-time industrial application needs. The first step runs on the log’s axis, while the second runs on each candidate knot’s axis. False positives from the first step are very rare (even with dry/dried logs), so no computational power is wasted for non-existing knots. Using this approach, we are able to see the internal defects of a log in real time in the production chain without having to cut it first, therefore being able to optimize even more the output of the chain on each client’s requirements

Strong coupling in chiral cavities: nonperturbative framework for enantiomer discrimination

The development of efficient techniques to distinguish mirror images of chiral molecules (enantiomers) is very important in both chemistry and physics. Enantiomers share most molecular properties except, for instance, the absorption of circularly polarized light. Enantiomer purification is therefore a challenging task that requires specialized equipment. Strong coupling between quantized fields and matter (e.g. in optical cavities) is a promising technique to modify molecular processes in a non-invasive way. The modulation of molecular properties is achieved by changing the field characteristics. In this work, we investigate whether strong coupling to circularly polarized electromagnetic fields is a viable way to discriminate chiral molecules. To this end, we develop a nonperturbative framework to calculate the behavior of molecules in chiral cavities. We show that in this setting the enantiomers have different energies -- that is, one is more stable than the other. The field-induced energy differences are also shown to give rise to enantiospecific signatures in rotational spectra.Comment: 18 pages and 14 figure

Thinning in black pine (Pinus nigra J.F.Arnold) forests: the economic sustainability of the wood-energy supply chain in a case study in Italy

In Italy, black pine has been largely used in reforestation projects in the past. Most of these reforestations are characterized by a high instability, vulnerability, and a limited resistance to atmospheric agents. In this situation, it is crucial to define silvicultural interventions able to increase the ecological stability of black pine stands and at the same time to guarantee the economic sustainability of the wood products obtained. Thinning in black pine forests can provide wood material for energy use. The main aim of the present study was to investigate the economic sustainability of a local wood-energy supply chain applying three different forest management options. The case study was Monte Morello forest, a degraded black pine forest located in Central Italy. The results show that the long-term economic sustainability of the wood-energy supply chain is ensured only when the use of bio-fuel is characterized by high energy efficiency. In addition, the results show that public contributions are fundamental to ensure that silvicultural interventions are realized with a positive economic balance and that to surmount this situation many loggings companies are organizing. Finally, the results highlighted the importance of the quantities of thermal energy sold to ensure the economic and environmental efficiency of the wood-energy supply chain