Seminář se koná každé úterý v 10:40 v posluchárně ÚTF MFF UK
v 10. patře katedrové budovy v Tróji, V Holešovičkách 2, Praha 8
Dark matter has proven to be one of the most elusive mysteries of modern-day physics. The fact that we have, as of yet, not been able to detect its interaction with standard model particles points to two most straightforward explanations. Either its interactions are too rare or too feeble for the technological limitations of our detectors. Phonons are some of the softest excitations one can produce in condensed matter systems. However, their readout has proven to be a very challenging task. In this seminar, I will talk about the possibility of employing chiral phonons together with surface-based magnetometric readout as dark matter detectors of tomorrow with unprecedented energy sensitivity.
During the seminar, the basic principles of laboratory X-ray tomography will be presented, as well as various less traditional tomographic methods - such as dual-energy tomography, triggering and 4D tomography, etc. In the field of materials research, the possibilities of studying time-dependent processes - fracture mechanics, deformation of 3D structures, etc. will be shown. In terms of research of cultural heritage objects, various possibilities of processing tomographic data to make otherwise difficult-to-access information visible will be demonstrated - stratigraphy of Gothic panel paintings, reading of old prints, research of ancient lead artifacts.
Svět bez internetu si dnes dokáže představit jen málokdo. Internet bez optických vláken a vláknových zesilovačů asi nikdo. Optická vlákna však nemusí sloužit jen v telekomunikacích; vláknové lasery nabízejí hrubou sílu pro řezání a sváření, ale také preciznost a přesnost například pro medicínské aplikace. Přijďte na přednášku a nechejte se vtáhnout do technologie přípravy skleněných vláken tenkých jako lidský vlas!
Berry curvature expresses the curvature of the reciprocal space, in a similar manner as magnetic field expresses curvature of the real space, resulting in a curved transport of electrons in solids. Therefore, it provides a key to describe various transport phenomena such as anomalous Hall effect, anomalous Nernst effect, orbital magnetization, topological insulators or electric polarization. As these transports are lossless, they are interesting for various applications. It is well known that Berry curvatures arise from the close proximity of hybridizing bands, providing topological flows of Berry curvature in the form of monopoles, one- or two-dimensional flows, or transitions between different dimensionalities. We use these properties to identify topological features of electronic band structure itself. This provides a novel view on details of the electronic structure in the whole Brillouin zone, inaccessible with traditional understanding of the band structure.
In this talk I describe some aspects of the modern theory of surface phase transitions. We begin with the simplest scenario of a fluid adsorbed at a planar wall, and the associated theory of wetting transitions, before turning attention to more complex geometries and the new phase transitions and hidden symmetries which emerge.
Jiří Horáček David Heyrovský