Scientific Series

Displaying 3397 - 3408 of 5012

Efficient Distributed Quantum Computing

Oliver Gray
University of Bristol
March 11, 2013

PIRSA:13030104
Quantum Information
One-photon and two-photon switching in graphene and optical nanomaterials

Mahi Singh
Western University
March 08, 2013

PIRSA:13030094
Condensed Matter
Is the electron round?

Edward Hinds
Imperial College London
March 08, 2013

PIRSA:13030100
Particle Physics
A Self-consistent Model of the Black Hole Evaporation

Yuki Yokokura
RIKEN
March 07, 2013

PIRSA:13030093
Quantum Gravity
Rethinking Cosmology
March 06, 2013

PIRSA:13030079
Cosmology
Non-perturbative problems in gauge theories: N=2 quiver QCD

Vasily Pestun
Institute for Advanced Study (IAS)
March 06, 2013

PIRSA:13030103
Quantum Fields and Strings
Thermodynamical Property of Entanglement Entropy for Excited States and Holographic Local Quench

Masahiro Nozaki
University of Chicago
March 05, 2013

PIRSA:13030081
Quantum Fields and Strings
The correlator of two vector and one axial current in QCD

Kirill Melnikov
Johns Hopkins University
March 05, 2013

PIRSA:13030099
Particle Physics
Getting the Most out of a Black Hole

Alexander Tchekhovskoy
Princeton University
March 04, 2013

PIRSA:13030102
Cosmology
Exploiting the Strong Gravitational Fields of Neutron Stars to Measure their Properties

Dimitrios Psaltis
University of Arizona
February 28, 2013

PIRSA:13020126
Strong Gravity
Gravitational anomaly and topological phases

Shinsei Ryu
University of Illinois at Urbana-Champaign (UIUC)
February 28, 2013

PIRSA:13020148
Condensed Matter
Quantum Gravity as Random Geometry

Vincent Rivasseau
University of Paris-Saclay
February 27, 2013

PIRSA:13020132
Quantum Gravity

Efficient Distributed Quantum Computing

Oliver Gray
University of Bristol
March 11, 2013

PIRSA:13030104
Quantum Information
I will explain how to simulate arbitrary quantum circuits on a distributed quantum computer (DQC), in which the pairs of qubits that are allowed to interact are restricted to the edges of some (connected) graph G. Even for graphs with only a modest number of long-range qubit interactions, such as the hypercube, this simulation is, in fact, efficient. Furthermore, for all graphs, the emulation scheme is very close to being optimal. Secondly I will present an efficient quantum algorithm for parallel unrestricted memory look-up. As an application, I will show that the space-time trade off for Element Distinctness and Collision Finding can be improved. Both results arise from applying the ideas of reversible sorting networks to quantum computing.http://arxiv.org/abs/1207.2307
One-photon and two-photon switching in graphene and optical nanomaterials

Mahi Singh
Western University
March 08, 2013

PIRSA:13030094
Condensed Matter
In this talk we will discuss both the one-photon and two-photon switching mechanisms in hybrid nanomaterials made from two or more semiconductor, metallic and optical nanostructures. The most prominent examples of these nanostructures are graphene, semiconductor quantum dots, metallic nanoparticles, and photonic and polaritonic crystals. Advances in nanoscience have allowed for the construction of these new classes of hybrid nanomaterials. Optical excitations in semiconductor nanostructures are electron-hole pairs (excitons) whereas excitations in metallic nanostructures are surface plasmons which are collective oscillations of electrons. Therefore, the combination of these systems can provide attractive opportunities to modify, design and control optical properties and to observe new phenomena which are based on exciton-plasmon interactions. It is expected that this research will provide a theoretical road map for the development of optical sensing and optical switching.
Is the electron round?

Edward Hinds
Imperial College London
March 08, 2013

PIRSA:13030100
Particle Physics
We have made a new measurement of the electron’s electric dipole moment (EDM) using a beam of YbF molecules. By measuring atto-eV energy shifts in a molecule, this experiment probes new physics at the tera-eV energy scale. According to the standard model, this EDM is d_e=10^(-38) e.cm – some eleven orders of magnitude below the current experimental limit. However, most extensions to the standard model predict much larger values, potentially accessible to measurement . Hence, the search for the electron EDM is a search for physics beyond the standard model. I will describe our experimental method, our current results and their implications for particle physics. I will also outline the prospects for further major improvement in sensitivity.
A Self-consistent Model of the Black Hole Evaporation

Yuki Yokokura
RIKEN
March 07, 2013

PIRSA:13030093
Quantum Gravity
We construct a self-consistent model which describes a black hole from formation to evaporation including the back reaction from the Hawking radiation. In the case where a null shell collapses, at the beginning the evaporation occurs, but it stops eventually, and a horizon and singularity appear. On the other hand, in the generic collapse process of a continuously distributed null matter, the black hole evaporates completely without forming a macroscopically large horizon nor singularity. We also find a stationary solution in the heat bath, which can be regarded as a normal thermodynamic object. (hep-th: 1302.4733)
Rethinking Cosmology
March 06, 2013

PIRSA:13030079
Cosmology
This talk will begin by discussing one by one the various reasons why cosmologists today consider the big bang inflationary cosmology to be the leading, if not proven, theory of the universe and then explaining why each of these reasons is flawed. This leads naturally to the question: what is the alternative? Understanding the flaws helps point the way.
Non-perturbative problems in gauge theories: N=2 quiver QCD

Vasily Pestun
Institute for Advanced Study (IAS)
March 06, 2013

PIRSA:13030103
Quantum Fields and Strings
Non-perturbative effects are responsible for the essential dynamical features of the four-dimensional gauge theories such as QCD. The N=2 supersymmetric four-dimensional theories are an interesting class of models in which non-perturbative computations can be carried out with arbitrary precision using localization of the path integrals. I will explain the new exact non-perturbative results and the relation to classical and quantum integrable systems for a large class of N=2 supersymmetric QCD.
Thermodynamical Property of Entanglement Entropy for Excited States and Holographic Local Quench

Masahiro Nozaki
University of Chicago
March 05, 2013

PIRSA:13030081
Quantum Fields and Strings
In this talk, we will describe our recent work. Recently, we focus on the thermodynamical property and time dependence of entanglement entropy. Using holography, we found that the entanglement entropy for a very small subsystem obeys a property which is analogous to the first law of thermodynamics when we excite the system. In relativistic setups, its effective temperature is proportional to the inverse of the subsystem size. This provides a universal relationship between the energy and the amount of quantum information. Moreover, we will propose a new holographic model of local quench and describe some results which we got by using this model. This talk is based on arXiv:1212.1164 [hep-th] and arXiv:1302.5703 [hep-th].
The correlator of two vector and one axial current in QCD

Kirill Melnikov
Johns Hopkins University
March 05, 2013

PIRSA:13030099
Particle Physics
It is known that the correlator of one axial and two vector currents, that receives leading contributions through one-loop fermion triangle diagrams, is not modified by QCD radiative corrections at two loops. It was suggested that this non-renormalization of the VVA correlator persists in higher orders in perturbative QCD as well. To check this assertion, I compute the three-loop QCD corrections to the VAA-correlator using the technique of asymptotic expansions. I find that these corrections do not vanish and that they are proportional to the QCD beta-function. I will also review some properties of the VVA correlator that were discovered in recent years.
Getting the Most out of a Black Hole

Alexander Tchekhovskoy
Princeton University
March 04, 2013

PIRSA:13030102
Cosmology
As black holes accrete surrounding gas, they often produce relativistic, collimated outflows, or jets. Jets are expected to form in the black hole vicinity making them powerful probes of strong-field gravity. However, how jet properties are connected to black hole and accretion flow properties has been unclear. Recent progress in computer simulations of black hole accretion enables studies of jet formation in unprecedented detail. For the first time, 3D general relativistic magnetohydrodynamic numerical simulations allow one to determine the maximum efficiency with which accretion onto black holes can power relativistic jets. I will present the dependence of this maximum efficiency on black hole spin and discuss how this dependence allows one to probe strong-field gravity. In realistic astrophysical systems, the angular momentum vector of the accretion flow can be tilted relative to the spin of the black hole. I will present the first simulations of jets from such tilted accretion systems and discuss their observational signatures.
Exploiting the Strong Gravitational Fields of Neutron Stars to Measure their Properties

Dimitrios Psaltis
University of Arizona
February 28, 2013

PIRSA:13020126
Strong Gravity
Neutron stars possess the strongest gravitational fields among stellar objects in the Universe that are not surrounded by a horizon. This causes the emission from their surfaces to be strongly lensed and deformed. Two upcoming space X-ray missions, ESA's LOFT and NASA's NICER, aim to use observations of lightcurves from spinning neutron stars to map their gravitational fields as well as measure their masses and radii. In this talk, I will discuss some unexpected strong-field phenomena that affect gravitational lensing in the vicinity of neutron stars. I will then show how we can use these phenomena to measure strong-field frame dragging and break degeneracies in the measured neutron-star masses and radii.
Gravitational anomaly and topological phases

Shinsei Ryu
University of Illinois at Urbana-Champaign (UIUC)
February 28, 2013

PIRSA:13020148
Condensed Matter
Since the quantum Hall effect, the notion of topological phases of matter has been extended to those that are well-defined (or: ``protected'') in the presence of a certain set of symmetries, and that exist in dimensions higher than two. In the (fractional) quantum Hall effects (and in ``chiral'' topological phases in general), Laughlin's thought experiment provides a key insight into their topological characterization; it shows a close connection between topological phases and quantum anomalies. By taking various examples, I will demonstrate that quantum anomalies serve as a useful tool to diagnose (and even define) topological properties of the systems. For chiral topological phases in (2+1) dimensions and (3+1) dimensional topological superconductors, I will discuss topological responses of the system which involve a cross correlation between thermal transport, angular momentum, and entropy. We also argue that gravitational anomaly is useful to study symmetry protected topological phases in (2+1) dimensions.
Quantum Gravity as Random Geometry

Vincent Rivasseau
University of Paris-Saclay
February 27, 2013

PIRSA:13020132
Quantum Gravity
Matrix models, random maps and Liouville field theory are prime tools which connect random geometry and quantum gravity in two dimensions. The tensor track is a new program to extend this connection to higher dimensions through the corresponding notions of tensor models, colored triangulations and tensor group field theories.

Title	Speaker(s)	Date	Talk Type	Info link
Efficient Distributed Quantum Computing	Oliver Gray	2013-03-11	Scientific Series	View details
One-photon and two-photon switching in graphene and optical nanomaterials	Mahi Singh	2013-03-08	Scientific Series	View details
Is the electron round?	Edward Hinds	2013-03-08	Scientific Series	View details
A Self-consistent Model of the Black Hole Evaporation	Yuki Yokokura	2013-03-07	Scientific Series	View details
Rethinking Cosmology		2013-03-06	Scientific Series	View details
Non-perturbative problems in gauge theories: N=2 quiver QCD	Vasily Pestun	2013-03-06	Scientific Series	View details
Thermodynamical Property of Entanglement Entropy for Excited States and Holographic Local Quench	Masahiro Nozaki	2013-03-05	Scientific Series	View details
The correlator of two vector and one axial current in QCD	Kirill Melnikov	2013-03-05	Scientific Series	View details
Getting the Most out of a Black Hole	Alexander Tchekhovskoy	2013-03-04	Scientific Series	View details
Exploiting the Strong Gravitational Fields of Neutron Stars to Measure their Properties	Dimitrios Psaltis	2013-02-28	Scientific Series	View details
Gravitational anomaly and topological phases	Shinsei Ryu	2013-02-28	Scientific Series	View details
Quantum Gravity as Random Geometry	Vincent Rivasseau	2013-02-27	Scientific Series	View details

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