Single-Focus Broadening Navigation in Concept Lattices

Formal concept analysis has been used to support information retrieval tasks in many domains, in particular the traditional "by keyword" document search with a conjunctive query interpretation. However, support for exploratory search or browsing needs new navigation algorithms that allow users (i) to continuously update the current query and (ii) to broaden as well as refine the result set. In this paper we investigate a step-wise navigation algorithm that supports both broadening and refinement operations. Our navigation operations maintain some useful algebraic properties. We motivate our approach on a dataset of wine reviews, which contains different facets of information

Advanced laser frequency stabilisation systems for mobile strontium optical lattice clocks

Strontium optical lattice clocks have undergone vast developments in the past decade with world leading frequency stability and uncertainty records. Now, a lot of scientists are moving from laboratory based clocks to transportable, and portable clocks for applications including space, fundamental science, finance, and communication. The research team at the University of Birmingham are working towards developing transportable apparatus for studying fundamental physics, global positioning system (GPS), and geodesy applications. This thesis reports on the progress towards two different transportable strontium optical lattice clocks, which we will call ‘miniclock’ and ‘Space Optical lattice Clock 2’ (SOC2). A diode-seeded tapered amplifier based narrow linewidth laser is developed and used to realise second stage cooling of strontium in miniclock apparatus. The laser has achieved a linewidth of 1 kHz after stabilising to a 3 cm long optical reference cavity. A multiple frequency stabilisation unit (FSU) for strontium lattice clocks is established. It is a robust, portable, and compact frequency stabilisation unit with a volume of 593 cm^3. Three different lasers are currently locked simultaneously to the FSU cavity, which could be extended to any number of lasers, enabling to use a single cavity for locking all the lasers required in a strontium lattice clock, except the clock laser. FSU is designed specifically for use in compact clocks. In the SOC2 system, realisation of clock transition and its characterisation are performed. A transition linewidth of 3 Hz is obtained for the SOC2 strontium clock. Further details and results are described in the thesis

Light-sheet microscopy: a tutorial

This paper is intended to give a comprehensive review of light-sheet (LS) microscopy from an optics perspective. As such, emphasis is placed on the advantages that LS microscope configurations present, given the degree of freedom gained by uncoupling the excitation and detection arms. The new imaging properties are first highlighted in terms of optical parameters and how these have enabled several biomedical applications. Then, the basics are presented for understanding how a LS microscope works. This is followed by a presentation of a tutorial for LS microscope designs, each working at different resolutions and for different applications. Then, based on a numerical Fourier analysis and given the multiple possibilities for generating the LS in the microscope (using Gaussian, Bessel, and Airy beams in the linear and nonlinear regimes), a systematic comparison of their optical performance is presented. Finally, based on advances in optics and photonics, the novel optical implementations possible in a LS microscope are highlighted.Peer ReviewedPostprint (published version

Proceedings of the 5th International Workshop "What can FCA do for Artificial Intelligence?", FCA4AI 2016(co-located with ECAI 2016, The Hague, Netherlands, August 30th 2016)

International audienceThese are the proceedings of the fifth edition of the FCA4AI workshop (http://www.fca4ai.hse.ru/). Formal Concept Analysis (FCA) is a mathematically well-founded theory aimed at data analysis and classification that can be used for many purposes, especially for Artificial Intelligence (AI) needs. The objective of the FCA4AI workshop is to investigate two main main issues: how can FCA support various AI activities (knowledge discovery, knowledge representation and reasoning, learning, data mining, NLP, information retrieval), and how can FCA be extended in order to help AI researchers to solve new and complex problems in their domain. Accordingly, topics of interest are related to the following: (i) Extensions of FCA for AI: pattern structures, projections, abstractions. (ii) Knowledge discovery based on FCA: classification, data mining, pattern mining, functional dependencies, biclustering, stability, visualization. (iii) Knowledge processing based on concept lattices: modeling, representation, reasoning. (iv) Application domains: natural language processing, information retrieval, recommendation, mining of web of data and of social networks, etc

Visual exploration of large geolocation-rich data sets using formal concept analysis

Information Scienc

a European community view

Within the last two decades, quantum technologies (QT) have made tremendous progress, moving from Nobel Prize award-winning experiments on quantum physics (1997: Chu, Cohen-Tanoudji, Phillips; 2001: Cornell, Ketterle, Wieman; 2005: Hall, Hänsch-, Glauber; 2012: Haroche, Wineland) into a cross-disciplinary field of applied research. Technologies are being developed now that explicitly address individual quantum states and make use of the 'strange' quantum properties, such as superposition and entanglement. The field comprises four domains: quantum communication, where individual or entangled photons are used to transmit data in a provably secure way; quantum simulation, where well-controlled quantum systems are used to reproduce the behaviour of other, less accessible quantum systems; quantum computation, which employs quantum effects to dramatically speed up certain calculations, such as number factoring; and quantum sensing and metrology, where the high sensitivity of coherent quantum systems to external perturbations is exploited to enhance the performance of measurements of physical quantities. In Europe, the QT community has profited from several EC funded coordination projects, which, among other things, have coordinated the creation of a 150-page QT Roadmap (http://qurope.eu/h2020/qtflagship/roadmap2016). This article presents an updated summary of this roadmap

Atom interferometry with ultracold atoms for inertial sensing

In light pulse atom interferometry wave packets are spatially separated and recombined in a coherent manner by interacting with laser pulses. Typically, two photon transitions are used to perform Rabi oscillations between two internal or/and external states to construct atom-optical elements, like beam splitters or mirrors. The phase difference accumulated between two atomictrajectories can be used to measure quantities such as accelerations or rotations. The velocity distribution and size of the employed atomic sources can significantly limit the efficiency of the atom-light interactions and thus the performance of the interferometer. To overcome this limitation, ensembles with momentum distributions far below the recoil of a photon are used, such as collimated Bose-Einstein condensates (BEC). Exploiting the properties of a BEC opens up a wide range of possibilities for new techniques and concepts, especially for increasing the sensitivity of measurements performed in small volumes. This work presents some of these novelties. The technique of an innovative (re-)launch mechanism helps to effectively increase the available interferometry time in compact gravimeter setups. A symmetric large momentum transfer in the form of a twin-lattice enables the enclosure of large space-time areas suitable for rotation measurements with high sensitivities. The exploitation of a BEC in combination with momentum transfer by double Bragg diffraction contributed to the development of a new concept. Using a single BEC, it is possible to create two simultaneous interferometers, which are employed to differentiate between rotations and accelerations. Its symmetry allows this geometry to be extended to form the basis of a six-axis quantum inertial measurement unit. Last but not least, the (re-)launch in combination with the symmetric splitting also provides the basis for a multi-loop atom interferometer. With this concept, an area can be enclosed that offers unique scalability for rotational sensors. Each atom interferometer is affected by the quality of its interrogating light fields. Therefore specific detrimental effects are pointed out in this work and possible mitigation strategies are presented subsequently. One way to reduce the susceptibility of light beams to distortions at apertures is to change their profile from the commonly used Gaussian profile to a more locally limited intensity distribution. For this purpose, the application of flat-top beam profiles is investigated. This brings the added benefit of a uniform power distribution, which helps to increase the beam area in which the ensemble of atoms can be manipulated with the same properties. Imperfections can also lead to position-dependent dipole forces that have a parasitic effect on the output of an interferometer. Especially for large momentum transfer techniques this has proven to be a limitation which can necessitate a compensation mechanism. To this end, a laser system is constructed that achieves the required high laser powers and includes additional frequency components. Many of the interferometry methods and concepts introduced are well suited for compact or transportable systems. For this purpose, a laser system based on telecommunication fiber components is presented, which represents an all-in-one solution for the generation, preparation and subsequent beam splitting of ultracold atoms. Inspired by all of the above, the future vision of a quantum sensor for inertial navigation applications is discussed

Workshop NotesInternational Workshop ``What can FCA do for Artificial Intelligence?'' (FCA4AI 2015)

International audienceThis volume includes the proceedings of the fourth edition of the FCA4AI --What can FCA do for Artificial Intelligence?-- Workshop co-located with the IJCAI 2015 Conference in Buenos Aires (Argentina). Formal Concept Analysis (FCA) is a mathematically well-founded theory aimed at data analysis and classification. FCA allows one to build a concept lattice and a system of dependencies (implications) which can be used for many AI needs, e.g. knowledge discovery, learning, knowledge representation, reasoning, ontology engineering, as well as information retrieval and text processing. There are many ``natural links'' between FCA and AI, and the present workshop is organized for discussing about these links and more generally for improving the links between knowledge discovery based on FCA and knowledge management in artificial intelligence