Topological crystalline insulators (TCIs) constitute a new class of quantum topological materials with the Dirac-like metallic surface states that cross the bulk semiconductor band gap and are topologically protected by crystalline mirror plane symmetry. The TCIs offer new ways of controlling topological states by applying perturbations lowering crystalline symmetry. The TCI states have been experimentally observed in (Pb,Sn)Se, SnTe and (Pb,Sn)Te crystals for both (001) and (111) surfaces. These IV-VI semiconductors undergo (at a specific tin content, temperature, and pressure) a band structure inversion driven by strong relativistic effects. Using angle- and spin-resolved photoemission technique we experimentally observed a temperature-driven topological phase transition from a trivial insulator to a TCI state below the band inversion point as well as revealed a characteristic vortical electronic spin polarization texture at the Dirac points.
In the lecture, I will summarize the basic physical model of this class of materials, present the TCI crystals and the key experimental methods applied to study these new surface states (photoemission, scanning tunneling spectroscopy, magneto-transport) and discuss new topological device concepts.
T.H. Hsieh et al., Nat. Commun. 3, 982 (2012); P. Dziawa et al., Nat. Mat. 11, 1023 (2012).
Zapraszamy do Nowej Auli (425), ul. Hoża 69 o godzinie 15:30
(Instytut Fizyki Teoretycznej i Astrofizyki Uniwersytetu Gdańskiego)
Multiphoton interference reveals strictly nonclassical phenomena. Its applications range from fundamental tests of quantum mechanics to photonic quantum information processing, in which a significant fraction of key experiments achieved so far comes from multiphoton state manipulation.The progress, both theoretical and experimental, of this rapidly advancing research will be presnted. The emphasis is given to the creation of photonic entanglement of various forms, tests of the completeness of quantum mechanics (in particular, violations of local realism), quantum information protocols for quantum communication (e.g., quantum teleportation, entanglement purification, and quantum repeater). The presentation will be limited to ‘‘few-photon’’ phenomena involving measurements of discrete observables, and will be based on Rev. Mod. Phys. 84, 777 (2012).
Zapraszamy do Nowej Auli (425), ul. Hoża 69 o godzinie 15:30
(Technische Universitaet Dresden)
The muon anomalous magnetic moment (g-2) is a fascinating precision observable which is sensitive to all interactions of the Standard Model. Electromagnetic, strong, and weak interactions, the masses of the heaviest particles such as top-quark and Higgs boson as well as non-perturbative low-energy hadron dynamics all enter the Standard Model prediction in a relevant way. Currently, this prediction deviates by more than 3sigma from the experimental determination. The deviation is a tantalizing hint for physics beyond the Standard Model.
In the colloquium the Standard Model prediction is reviewed and future experimental progress is indicated. We then focus on the possible contributions from physics beyond the Standard Model, particularly from supersymmetry. We show that, despite negative LHC search results, the deviation in g-2 could still well be due to effects from new physics, and at the same time g-2 places strong constraints on new physics
Zapraszamy do Nowej Auli (425), ul. Hoża 69 o godzinie 15:30
(University of Miami)
In recent years there has been a great deal of interest in black holes in higher dimensional gravity. This, in particular, has led to questions about the topology of black holes in higher dimensions. In this talk we review Hawking's classical theorem on the topology of black holes in 3+1 dimensions (and its connection to black hole uniqueness) and present a generalization of it to higher dimensions. We shall also discuss recent work on the topology of space exterior to a black hole. This is closely connected to the Principle of Topological Censorship, which roughly asserts that the topology of the region outside of all black holes (andwhite holes) should be simple. The results to be discussed rely onrecent developments in the theory of marginally outer trapped surfaces. This talk is based primarily on joint work with Rick Schoen, and with Michael Eichmair and Dan Pollack.
Zapraszamy do Nowej Auli (425), ul. Hoża 69 o godzinie 15:30
(Northeastern University, Boston)
Theoretical understanding of proton-proton collisions at the Large Hadron Collider is based on the standard model - a quantum field theory of quarks and leptons interacting with gauge fields. Some of the most important quantum field-theoretical observables are the amplitudes describing multi-particle, relativistic processes in which matter, antimatter particles and gauge bosons are scattered, created and/or annihilated. Over the last decade, there has been enormous progress in understanding the structure of scattering amplitudes in the standard model. It is less known that some significant progress has been also accomplished in gravity and in string theory, where the scattering amplitudes of hypothetical gravitons offer a testing ground for some new ideas about the relation of gauge theory to quantum gravity. I will describe some recent developments which point towards a fascinating unity of all gauge, gravity and string amplitudes
Zapraszamy do Nowej Auli (425), ul. Hoża 69 o godzinie 15:30
(Ecole Normale Superieure)
Remarkable progress has been made in the statistical physics of disordered systems in the last three decades. A system can be disordered either because each particle (or spin, or neuron, or economic agent...) is different from all other ones, or because it sees a differentenvironment: generally this happens in a glassy phase, in which the various particles freeze in some positions which look random, and don't have the periodicity of a crystal. In these cases, it turns out to be very difficult to even understand the basics of the collective behaviour, such as the phase diagram. This field has been one of the main developments of statistical physics, starting with spin glass theory. Offsprings developed gradually towards such diverse systems as combinatorial optimization problems, error correcting codes, neural networks, structural glasses, or systems of interacting economic agents with heteronegeous strategies. Recently, I have started to consider the vast potentialities offered by cross fertilizations between the field of Statistical Physics and that of Information Theory, which I will develop throughout my conference.
Zapraszamy do Nowej Auli (425), ul. Hoża 69 o godzinie 15:30
(Institute of Physics, Wrocław University of Technology)
Composite fermions, loosely defined as bound states of electrons and magnetic flux quanta, are emergent particles in interacting 2D systems in high magnetic fields, originally proposed to unify fractional and integral quantum Hall effects. Recently this concept was applied to the most exotic topological electron phases characterized by non-Abelian quasiparticle statistics. In my talk, I will briefly review the ideas of composite fermions, topological order, and braid statistics, and present an original extension of the composite fermion model to describe in an intuitive fashion the emergence of non-Abelian statistics in to so-called parafermion fractional quantum Hall states, especially attractive in the context of topological quantum computation.
Zapraszamy do Nowej Auli (425), ul. Hoża 69 o godzinie 15:30
(Ecole Normale Superieure)
Many of the biological networks inside cells can be thought of as transmitting information from the inputs (e.g., the concentrations of transcription factors or other signaling molecules) to their outputs (e.g., the expression levels of various genes). Given the molecular limits (small concentrations, intrinsic randomness), not all networks perform equally well, and maximizing information transmission provides a optimization principle from which we might hope to derive the properties of real regulatory networks. Inspired by the precision of transmission of positional information in the early development of the fly embryo, I will discuss the properties of specific small networks that can optimally transmit information. Concretely, I will show how the form of molecular noise drives predictions not just of the qualitative network topology but also how the quantitative parameters for the input/output relations at the nodes of the network depend on the molecular regulator elements. I will then show how we can consider time dependent information transmission.
Zapraszamy do Nowej Auli (425), ul. Hoża 69 o godzinie 15:30
(Institute of Mathematics Polish Academy of Sciences;National Centre for Nuclear Research)
I shall present the current status of searches for gravitational radiation.Gravitational waves are one of the predictions of the Einstein's general theory of relativity. I shall briefly introduce this phenomenon, review astrophysical sources of gravitational radiation and present evidence for its existence.Currently there is operating a world wide network of large scale laser interferometric antennas aiming at direct detection of gravitational waves. These detectors involve challenging technologies. Sophisticated data analysis methods are used to search for gravitational wave signals in the noise of the detectors. I shall present the observational results obtained so far from the analysis of data collected by these detectors. I shall stressimportance of joint searches with other astronomical observatories. No gravitational waves have been detected so far but exciting results are expected in a few years time when detectors with advanced configuration start operating. I shall briefly mention other current gravitational wave detection projects and projects planned in the future. I shall also describe the effort of researches in Poland in this field.
Zapraszamy do Nowej Auli (425), ul. Hoża 69 o godzinie 15:30
(Institut fuer Kernphysik and ExtreMe Matter Institute EMMI ;Technische Universitaet Darmstadt)
Three-body forces are especially important in strongly interacting systems. In nuclear physics, three-body forces are predicted by effective field theories of Quantum Chromodynamics. I will show that exotic nuclei become increasingly sensitive to three-nucleon forces and how experiments with neutron-rich nuclei test and constrain these subtle components of nuclear forces. The same three-body forces impact neutron-rich matter in neutron stars and other extreme neutron-rich astrophysical environments. Three-nucleon forces therefore provide an exciting link between experimental, theoretical and observational physics frontiers
Zapraszamy do Nowej Auli (425), ul. Hoża 69 o godzinie 15:30
(Dipartimento di Fisica-Università degli Studi di Milano)
Several quantities of interest in physics are non-linear functions of the density matrix and cannot, even in principle, correspond to proper quantum observables. Any method aimed to determine the value of these quantities should resort to indirect measurements and thus corresponds to a parameter estimation problem whose solution, i.e. the determination of the most precise estimator, unavoidably involves an optimization procedure. In this lecture I review local quantum estimation theory, which allows to quantify quantum noise in the measurements of non observable quantities and provides a tools for the characterization of signals and devices, e.g. in quantum technology. Explicit formulas for the symmetric logarithmic derivative and the quantum Fisher information of relevant families of quantum states are presented, and the connection between the optmization procedure and the geometry of quantum statistical models is discussed in some details. Finally, few applications, ranging from quantum optics to critical systems are illustrated
Zapraszamy do Nowej Auli (425), ul. Hoża 69 o godzinie 15:30
(NCBJ; Universiteit van Amsterdam)
Ultra-relativistic heavy ion collision programs at RHIC and LHC probe the properties of matter under extreme conditions in which quarks and gluons are liberated from hadrons and form the so-called quark-gluon plasma. I will discuss the progress on theoretical understanding the formation of the quark-gluon plasma in heavy ion collisions, and related questions, coming from the first principle calculations in the models of strong interactions solvable using the gauge/gravity duality, also known as AdS/CFT or (gravitational) holography. This leads to a fascinating connection with gravitational physics, in particular black hole formation and dynamics, which I will discuss in detail.
