Quantum fluids of light

This article reviews recent theoretical and experimental advances in the fundamental understanding and active control of quantum fluids of light in nonlinear optical systems. In presence of effective photon-photon interactions induced by the optical nonlinearity of the medium, a many-photon system can behave collectively as a quantum fluid with a number of novel features stemming from its intrinsically non-equilibrium nature. We present a rich variety of photon hydrodynamical effects that have been recently observed, from the superfluid flow around a defect at low speeds, to the appearance of a Mach-Cherenkov cone in a supersonic flow, to the hydrodynamic formation of topological excitations such as quantized vortices and dark solitons at the surface of large impenetrable obstacles. While our review is mostly focused on a class of semiconductor systems that have been extensively studied in recent years (namely planar semiconductor microcavities in the strong light-matter coupling regime having cavity polaritons as elementary excitations), the very concept of quantum fluids of light applies to a broad spectrum of systems, ranging from bulk nonlinear crystals, to atomic clouds embedded in optical fibers and cavities, to photonic crystal cavities, to superconducting quantum circuits based on Josephson junctions. The conclusive part of our article is devoted to a review of the exciting perspectives to achieve strongly correlated photon gases. In particular, we present different mechanisms to obtain efficient photon blockade, we discuss the novel quantum phases that are expected to appear in arrays of strongly nonlinear cavities, and we point out the rich phenomenology offered by the implementation of artificial gauge fields for photons.Comment: Accepted for publication on Rev. Mod. Phys. (in press, 2012

Analyzing and Modeling Real-World Phenomena with Complex Networks: A Survey of Applications

The success of new scientific areas can be assessed by their potential for contributing to new theoretical approaches and in applications to real-world problems. Complex networks have fared extremely well in both of these aspects, with their sound theoretical basis developed over the years and with a variety of applications. In this survey, we analyze the applications of complex networks to real-world problems and data, with emphasis in representation, analysis and modeling, after an introduction to the main concepts and models. A diversity of phenomena are surveyed, which may be classified into no less than 22 areas, providing a clear indication of the impact of the field of complex networks.Comment: 103 pages, 3 figures and 7 tables. A working manuscript, suggestions are welcome

Art and Technology: coherence, connectedness, and the integrative field

Merged with duplicate record 10026.1/690 on 03.04.2017 by CS (TIS)This thesis is a theoretical and practical intervention in the field of art and technology. It proceeds from the re-examination of four specific domains that in the past 40 years have considerably informed the invention of new aesthetic forms. They are: art, science, nature and technology. We have identified that each one of these domains and the way they inform one another reflects the influence of a Western analytical tradition based on fragmentation, dichotomies and dualities. In consequence of this, art of the last decades has suffered from a sort of mechanistic thought which results from a predominantly weary aesthetic model, founded in dualities such as: object/process, form/behaviour, meaning/information. The main question that the present study addresses is how to overcome this predominantly reductionist inheritance and to develop an aesthetic model able to interconnect in an integrative fashion those disparate domains, respective discourses and practices? The answer to this question, developed throughout this thesis, is an aesthetic principle built upon the notions of resonance, coherence and field models, rooted in an integrative view of living organisms based on the theory of biophotons. This constitutes the main contribution of the thesis to new knowledge. The theoretical approach of this thesis is developed upon the revision of the concept of form, supported by a Gestalt analysis as provided by Rudolf Arnheim, and has involved the consideration of the ideas of Gilbert Simondon (the concept of "concretisation") and Vilem Flusser (the concept of "apparatus"), in order to gain a deeper insight into the nature of technology. In conclusion, the practice-based methodology of this thesis has been to develop artworks based on the confluence of living organisms (plants) and artificial systems in order to permit empirical observation and reflection on the proposed theory. The major outcome of the practice is the artwork "Breathing", a hybrid creature made of a living organism (a plant) and an artificial system. The creature responds to its environment through movement, light and the noise of its mechanical parts and interacts with the observer through his/her act of breathing. This work is the result of an investigation into plants as sensitive agents for the creation of art. The intention was to explore new forms of artistic experience through the dialogue of natural and artificial processes

Exploring Text Mining and Analytics for Applications in Public Security: An in-depth dive into a systematic literature review

Text mining and related analytics emerge as a technological approach to support human activities in extracting useful knowledge through texts in several formats. From a managerial point of view, it can help organizations in planning and decision-making processes, providing information that was not previously evident through textual materials produced internally or even externally. In this context, within the public/governmental scope, public security agencies are great beneficiaries of the tools associated with text mining, in several aspects, from applications in the criminal area to the collection of people's opinions and sentiments about the actions taken to promote their welfare. This article reports details of a systematic literature review focused on identifying the main areas of text mining application in public security, the most recurrent technological tools, and future research directions. The searches covered four major article bases (Scopus, Web of Science, IEEE Xplore, and ACM Digital Library), selecting 194 materials published between 2014 and the first half of 2021, among journals, conferences, and book chapters. There were several findings concerning the targets of the literature review, as presented in the results of this article

Reference frames, superselection rules, and quantum information

Recently, there has been much interest in a new kind of ``unspeakable'' quantum information that stands to regular quantum information in the same way that a direction in space or a moment in time stands to a classical bit string: the former can only be encoded using particular degrees of freedom while the latter are indifferent to the physical nature of the information carriers. The problem of correlating distant reference frames, of which aligning Cartesian axes and synchronizing clocks are important instances, is an example of a task that requires the exchange of unspeakable information and for which it is interesting to determine the fundamental quantum limit of efficiency. There have also been many investigations into the information theory that is appropriate for parties that lack reference frames or that lack correlation between their reference frames, restrictions that result in global and local superselection rules. In the presence of these, quantum unspeakable information becomes a new kind of resource that can be manipulated, depleted, quantified, etcetera. Methods have also been developed to contend with these restrictions using relational encodings, particularly in the context of computation, cryptography, communication, and the manipulation of entanglement. This article reviews the role of reference frames and superselection rules in the theory of quantum information processing.Comment: 55 pages, published versio