Spectroscopic studies in open quantum systems

The spectroscopic properties of an open quantum system are determined by the eigenvalues and eigenfunctions of an effective Hamiltonian H consisting of the Hamiltonian H_0 of the corresponding closed system and a non-Hermitian correction term W arising from the interaction via the continuum of decay channels. The eigenvalues E_R of H are complex. They are the poles of the S-matrix and provide both the energies and widths of the states. We illustrate the interplay between Re(H) and Im(H) by means of the different interference phenomena between two neighboured resonance states. Level repulsion along the real axis appears if the interaction is caused mainly by Re(H) while a bifurcation of the widths appears if the interaction occurs mainly due to Im(H). We then calculate the poles of the S-matrix and the corresponding wavefunctions for a rectangular microwave resonator with a scatter as a function of the area of the resonator as well as of the degree of opening to a guide. The calculations are performed by using the method of exterior complex scaling. Re(W) and Im(W) cause changes in the structure of the wavefunctions which are permanent, as a rule. At full opening to the lead, short-lived collective states are formed together with long-lived trapped states. The wavefunctions of the short-lived states at full opening to the lead are very different from those at small opening. The resonance picture obtained from the microwave resonator shows all the characteristic features known from the study of many-body systems in spite of the absence of two-body forces. The poles of the S-matrix determine the conductance of the resonator. Effects arising from the interplay between resonance trapping and level repulsion along the real axis are not involved in the statistical theory.Comment: The six jpg files are not included in the tex-fil

Environmental archaeology from a Roman Villa at Spoletino (Viterbo, Italy)

Abstract: My thesis focuses on the reconstruction of environmental conditions and land use in the Tiber Valley during the 1st century AD, as highlighted by a combination of archaeological and archaeobotanical studies. The study site is a cistern connected with a Roman Villa at Spoletino, in the province of Viterbo, which was a very important rural site of central Italy during the Roman Imperial Age. The importance of the site lays in the exceptional richness of different kinds of materials, especially in a high quantity of pottery pertaining to various typologies (from domestic to storage use), recovered from a large cistern and studied within a collaboration between Sapienza Università di Roma (Dipartimento di Biologia Ambientale and Dipartimento di Scienze dell’Antichità) and the Dipartimento di Studi Umanistici of Università di Roma Tre. The discovery of the cistern, with its important artifacts, dates back to 2014 and the excavation works continued until 2018: the site retains a special attention as the region’s organization in the Roman period is quite unknown, whereas it was of fundamental significance for its advantageous position within the Tiber valley granting a direct connection to Rome itself. Multiple methodological approaches were used to study plant micro- and macroremains, including pollen, diatoms, and charcoal, identified through light and stereomicroscope, as well as through Environmental Scanning Electron Microscope (ESEM). The results shed light on the natural conditions of the area surrounding the Roman Villa during the early Roman Imperial Age as indicated by pollen analysis, on the aquatic environment of the cistern reconstructed through diatoms, and on the human activity towards exploitation of the natural resources and cultivation of fruit trees, as provided by charcoal analysis, complemented by pollen data. The main floristic elements of the surrounding woodlands were deciduous and evergreen oaks, accompanied by other tree taxa, such as elms. My data suggest intentional plantation and management of Olea, Juglans and possibly Prunus, while herbaceous taxa indicate agropastoral activities in the Spoletino area. The variety and complementarity of plant remains provide new insights into the relation between man and landscape in the Roman times, in this strategic area in the Tiber Valley that was until now uninvestigated from both the archaeological and archaeobotanical points of vie