Phase separation and temperature effects in mixture of two atomic species

This thesis investigates bosonic mixtures in ultra-cold atom systems. We mainly focus on mixtures of two bosonic twin-species trapped in optical lattices, paying particular attention to the properties of spatial separation. The study is carried out by means of the path-integral quantum Monte Carlo by the two-worm algorithm and by analytical calculations where the complexity of the system allows it. The mixture is trapped in a square optical lattice at different filling and temperature conditions. We explore the ground-state phase diagram showing that various quantum phases can arise depending on the interplay between intra- and inter-species interactions. Demixed phases, characterized by spatial separation of the two species, are studied in details determining under which conditions they can be stabilized. The influence of temperature, filling factor and harmonic trap on phase separation is also investigated. An interesting dependence of the degree of demixing from temperature has been found, suggesting new ways to measure the temperature of a two-component bosonic mixture. We also study spatial phase separation in the simple case of a two-component mixture in a double-well potential both numerically and by means of the Bogoliubov approximaton. We show that even in this simple case the main features of the mixing/ demixing phase transitions are observed, and that the transition is characterized by a spectral collapse of the energy eigenvalues reflecting the dramatic change of algebraic structure of the model

Residual entropy and critical behavior of two interacting boson species in a double well

Motivated by the importance of entanglement and correlation indicators in the analysis of quantum systems, we study the equilibrium and the bipartite residual entropy in a two-species Bose Hubbard dimer when the spatial phase separation of the two species takes place. We consider both the zero and non-zero-temperature regime. We present different kinds of residual entropies (each one associated to a different way of partitioning the system), and we show that they strictly depend on the specific quantum phase characterizing the two species (supermixed, mixed or demixed) even at finite temperature. To provide a deeper physical insight into the zero-temperature scenario, we apply the fully-analytical variational approach based on su(2) coherent states and provide a considerably good approximation of the entanglement entropy. Finally, we show that the effectiveness of bipartite residual entropy as a critical indicator at non-zero temperature is unchanged when considering a restricted combination of energy eigenstates.Comment: 18 pages, 9 figure

A topological signature of multipartite entanglement

In this manuscript, we present a proposal to relate topological structure of worldline configurations to multipartite entanglement. Configurations result from the path-integral formulation of the density matrix in the limit of zero temperature. We consider hard-core bosons for which configurations, i.e. collections of particle paths, can be seen as geometric braids with a certain topological structure. We propose that properties of worldline configurations may realize a comprehensive deciphering of multipartite entanglement. By means of Monte Carlo calculations, we study checkerboard, stripe, valence-bond solids, $\mathbb{Z}_2$ topologically ordered spin liquid, and superfluid phase. We find that each ground-state is characterized by a certain `topological spectrum' which can be used to differentiate among different ground-states.Comment: 6 pages, 3 figures and supplemental material. Version 2 focuses on the discussion of topological signatures of multipartite entanglement in the ground-state expansion, with added results. The study of phase transitions and permutation cycles in version 1 has been moved to a new manuscript: arXiv:1912.00080. Version 3 corrected some typos and reference

Permutation cycles of hardcore Bose-Hubbard models on square and Kagome lattices

In this paper, we study the statistics of permutation cycles of ground-state hardcore lattice bosons described by various two-dimensional Bose-Hubbard-type models on both square and Kagome lattices. We find that it is possible to differentiate quantum phases by the statistics of permutations cycles. Indeed, features in the permutation cycles statistics can be used to uniquely identify certain insulating phases, and are consistent with local resonances of occupation numbers in the ground-state expansion of the phase. We also confirm that suitable quantities derived from the probability distribution of the length of permutation cycles can be used to detect superfluid to insulator phase transitions.Comment: 7 pages, 9 figures. The study of phase transitions and permutation cycles originally part of manuscript arXiv:1905.07454v1 (version 1) has been moved to this manuscript while the discussion of topological signatures of multipartite entanglement in the ground-state expansion has been further developed in version 2 of manuscript arXiv:1905.07454v

UAV Deployment Exercise for Mapping Purposes: Evaluation of Emergency Response Applications

Exploiting the decrease of costs related to UAV technology, the humanitarian community started piloting the use of similar systems in humanitarian crises several years ago in different application fields, i.e., disaster mapping and information gathering, community capacity building, logistics and even transportation of goods. Part of the author’s group, composed of researchers in the field of applied geomatics, has been piloting the use of UAVs since 2006, with a specific focus on disaster management application. In the framework of such activities, a UAV deployment exercise was jointly organized with the Regional Civil Protection authority, mainly aimed at assessing the operational procedures to deploy UAVs for mapping purposes and the usability of the acquired data in an emergency response context. In the paper the technical features of the UAV platforms will be described, comparing the main advantages/disadvantages of fixed-wing versus rotor platforms. The main phases of the adopted operational procedure will be discussed and assessed especially in terms of time required to carry out each step, highlighting potential bottlenecks and in view of the national regulation framework, which is rapidly evolving. Different methodologies for the processing of the acquired data will be described and discussed, evaluating the fitness for emergency response applications

Digitalization and Spatial Documentation of Post-Earthquake Temporary Housing in Central Italy: An Integrated Geomatic Approach Involving UAV and a GIS-Based System

Geoinformation and aerial data collection are essential during post-earthquake emergency response. This research focuses on the long-lasting spatial impacts of temporary solutions, which have persisted in regions of Central Italy affected by catastrophic seismic events over the past 25 years, significantly and permanently altering their landscapes. The paper analyses the role of geomatic and photogrammetric tools in documenting the emergency process and projects in post-disaster phases. An Atlas of Temporary Architectures is proposed, which defines a common semantic and geometric codification for mapping temporary housing from territorial to urban and building scales. The paper presents an implementation of attribute specification in existing official cartographic data, including geometric entities in a 3D GIS data model platform for documenting and digitalising these provisional contexts. To achieve this platform, UAV point clouds are integrated with non-metric data to ensure a complete description in a multiscalar approach. Accurate topographic modifications can be captured by extracting very high-resolution orthophotos and elevation models (DSM and DTM). The results have been validated in Visso (Macerata), a small historical mountain village in Central Italy which was heavily damaged by the seismic events of 2016/2017. The integrated approach overcomes the existing gaps and emphasizes the importance of managing heterogeneous geospatial emergency data for classification purposes. It also highlights the need to enhance an interoperable knowledge base method for post-disaster temporary responses. By combining geomatic tools with architectural studies, these visualization techniques can support national and local organizations responsible for post-earthquake management through a 3D modelling method to aid future transformations or interventions following other natural disasters

Land-use history and topographic gradients as driving factors of subalpine Larix decidua forests

none6restrictedMatteo Garbarino;Emanuele Lingua;Peter J. Weisberg;Alessandra Bottero;Fabio Meloni;Renzo MottaMatteo, Garbarino; Lingua, Emanuele; Peter J., Weisberg; Alessandra, Bottero; Fabio, Meloni; Renzo, Mott

Un benchmark per la segmentazione semantica di nuvole di punti di beni culturali

La mancanza di dati di benchmark per la segmentazione semantica di nuvole di punti dei beni culturali sta ostacolando lo sviluppo di soluzioni di classificazione automatica in questo campo. I dati 3D e le nuvole di punti del nostro patrimonio culturale rappresentano strutture geometriche complesse con classi non convenzionali, le quali impediscono la semplice implementazione dei metodi già disponibili, sviluppati in altri campi o per altri tipi di dati. La segmentazione semantica dei dati 3D del patrimonio aiuterebbe la comunità nella migliore comprensione e analisi dei gemelli digitali (digital twins), faciliterebbe le operazioni di salvaguardia e supporterebbe molte altre attività legate al settore dei beni culturali. In questo contributo si presenta il primo benchmark con milioni di punti 3D annotati manualmente appartenenti a scenari del patrimonio, realizzati per facilitare lo sviluppo, l'addestramento, il test e la valutazione di metodi e algoritmi di apprendimento automatico nel campo dei beni architettonici. Il benchmark proposto, disponibile su http://archdataset.polito.it/, comprende set di dati e risultati di classificazione finalizzati a migliorare i confronti e approfondire i punti di forza e di debolezza dei diversi approcci di machine e deep learning per la segmentazione semantica della nuvola di punti del patrimonio, oltre a promuovere una forma di crowdsourcing per arricchire il database già annotato

L'AVVENTURA DELLA LINGUA: MARIA LUISA ALTIERI BIAGI FRA RICERCA E DIDATTICA: PRESENTAZIONE di Silvia Morgana

Gli allievi di Maria Luisa Altieri Biagi ripercorrono in tre articoli il suo lungo impegno teorico e civile per l’educazione linguistica e la formazione degli insegnanti. Angela Chiantera e Cristiana De Santis analizzano le sue molteplici esperienze per il rinnovamento della didattica linguistica nella stretta connessione tra lingua e pensiero. Francesca Gatta ne illustra gli studi sulla letteratura contemporanea e le analisi del testo letterario in prospettiva di educazione linguistica, mentre Fabio Atzori evidenzia i rapporti tra i suoi fondamentali studi sulla lingua scientifica e la sua produzione per la scuola.   The adventure of language: Maria Luisa Altieri Biagi from research to teaching The students of Maria Luisa Altieri Biagi review her long-standing theoretical and civil commitment to language education and teacher training in three articles. Angela Chiantera and Cristiana De Santis analyze her multiple efforts to renew language teaching with focus on the close connection between language and thought. Francesca Gatta illustrates her studies on contemporary literature and the analysis of the literary text in the perspective of language education, while Fabio Atzori highlights the relationship between her fundamental studies on scientific language and her production for schools