Displaying all lectures given by:

PIRSA:20030071  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Categorified sheaf theory and the spectral Langlands TQFT
Abstract: It is expected that the Betti version of the geometric Langlands program should ultimately be about the equivalence of two 4-dimensional topological field theories. In this talk I will give an overview of ongoing work in categorified sheaf theory and explain how one can use it to describe the catego... read more
Date: 12/03/2020 - 1:30 pm

PIRSA:20020074  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Coordinate Charts on Character Varieties via Non-abelianization
Abstract: Classical work by Thurston in the theory of surfaces gives symplectic co-ordinate charts on Teichmüller space, associated to quadratic differentials. Motivated by wall crossing in 4d field theories Gaiotto, Moore and Neitzke defined a generalization of these; giving maps from the moduli of on... read more
Date: 27/02/2020 - 1:30 pm

PIRSA:19040095  ( MP4 Medium Res , MP3 , PDF ) Which Format?
From cold to lukewarm to hot electrons
Speaker(s): , Joy Montgomery
Abstract: I will present a study of the single-particle properties of hot, lukewarm and cold electrons that coexist in the two-dimensional antiferromagnetic quantum critical metal within a unified theory. I will show how to generalize the theory that describes the interaction of critical spin-density wave flu... read more
Date: 22/04/2019 - 2:45 pm

PIRSA:19040117  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Tensor renormalization group in bosonic field theory
Abstract: We compute the partition function of a massive free boson in a square lattice using a tensor network algorithm. We introduce a singular value decomposition (SVD) of continuous matrices that leads to very accurate numerical results. It is shown the emergence of a CDL fixed point structure. In the mas... read more
Date: 08/04/2019 - 3:00 pm

PIRSA:19010075  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Chris Cade: Post-selected classical query complexity
Abstract: The precise relationship between post-selected classical and  post-selected quantum computation is an open problem in complexity  theory. Post-selection has proven to be a useful tool in uncovering some  of the differences between quantum and classical theories, in&... read more
Date: 23/01/2019 - 4:00 pm

PIRSA:18120022  ( MP4 Medium Res , MP3 , PDF ) Which Format?
On the interplay of topology and interactions: Reduced topological classification and fractional Fermi liquid
Abstract: This seminar will focus on two cases where the interplay of topology and interactions allows for phases that go beyond simple quasi-particle descriptions. Both models are amenable to sign free auxiliary field quantum Monte Carlo simulations. First, we design a two-dimensional model consisting of... read more
Date: 11/12/2018 - 11:00 am

PIRSA:18120014  ( MP4 Medium Res , MP3 , PDF ) Which Format?
On the Brink of Fractionalization - Yichen Hu
Abstract: Systems of strongly interacting particles can give rise to topological phases beyond non-interacting limit.  Although unique features of strongly interacting topological phases, such as fractionalization of quantum degrees of freedom, have important applications in quantum information proce... read more
Date: 04/12/2018 - 3:30 pm

PIRSA:18110089  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Symmetry-protected self-correcting quantum memories
Abstract: A self-correcting quantum memory can store and protect quantum information for a time that increases without bound with the system size, without the need for active error correction. We demonstrate that symmetry can lead to self-correction in 3D spin lattice models. In particular, we investigate cod... read more
Date: 21/11/2018 - 4:00 pm

PIRSA:18100046  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Fault-tolerant gates via homological product codes
Abstract: I will present a method for the implementation of a universal set of fault-tolerant logical gates using homological product codes. In particular, I will show how one can fault-tolerantly map between different encoded representations of a given logical state, enabling the application of different cla... read more
Date: 03/10/2018 - 4:00 pm

PIRSA:18080077  ( MP4 Medium Res , MP3 , PDF ) Which Format?
A categorified Dold–Kan correspondence
Abstract: Various recent developments, in particular in the context of topological Fukaya categories, seem to be glimpses of an emerging theory of categorified homotopical and homological algebra. The increasing number of meaningful examples and constructions make it desirable to develop such a theory system... read more
Date: 16/08/2018 - 9:00 am

PIRSA:18080055  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Stability conditions on Fukaya categories of surfaces: Some new techniques and results
Abstract: In this talk I will present some upcoming work on Bridgeland stability conditions on partially wrapped Fukaya categories of topological surfaces. The main result is a proof that the stability conditions defined by Haiden, Katzarkov and Kontsevich using quadratic differentials cover the entire stabil... read more
Date: 15/08/2018 - 4:30 pm

PIRSA:18080080  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Moduli of connexions on open varieties
Abstract: This is a joint work with T. Pantev. In this talk, we will discuss moduli of flat bundles on smooth algebraic varieties, with possibly irregular singularities at infinity. For this, we use the notion of “formal boundary”, previously studied by Ben Bassat-Temkin, Efimov and Hennion– Porta–... read more
Date: 14/08/2018 - 9:00 am

PIRSA:18050059  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Reconstructing quantum theory from diagrammatic postulates
Abstract: There has been a dissatisfaction with the postulates of quantum mechanics essentially since the moment that those postulates were first written down. Over the years since there have therefore been many attempts (some successful and some less so) to reconstruct quantum theory from various sets of pos... read more
Date: 23/05/2018 - 3:30 pm

PIRSA:18050062  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Probing Ultralight Bosons with Binary Black Holes
Abstract: Ultralight bosons exist in various proposed extensions to the Standard Model, which can form condensates around rapidly rotating black holes through a process called superradiance. These boson clouds have many interesting observational consequences, such as the continuous emission of monochromatic g... read more
Date: 08/05/2018 - 1:00 pm

PIRSA:18040114  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Symmetric Informationally Complete Measurements Identify the Essential Difference between Classical and Quantum
Abstract: In this talk we describe a general procedure for associating a minimal informationally-complete quantum measurement (or MIC) with a probabilistic representation of quantum theory. Towards this, we make use of the idea that the Born Rule is a consistency criterion among subjectively assigned probabil... read more
Date: 10/04/2018 - 2:00 pm

PIRSA:18010085  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Universal quantum computation in thermal equilibrium
Abstract: Adiabatic quantum computation (AQC) is a method for performing universal quantum computation in the ground state of a slowly evolving local Hamiltonian, and in an ideal setting AQC is known to capture all of the computational power of the  quantum circuit model.  However, despite h... read more
Date: 24/01/2018 - 4:00 pm

PIRSA:17110053  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Gravitational shockwaves on rotating black holes
Abstract: Gravitational shockwaves may signal the breakdown of effective field theory near black hole horizons. Motivated by this, I will revisit the Dray-‘t Hooft solution and explain how to generalize it to the Kerr-Newman background. In doing so I will emphasize the method of spin coefficients (the Newma... read more
Date: 28/11/2017 - 2:30 pm

PIRSA:17110079  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Could LIGO's black holes be primordial and what is an easy way to figure that out?
Date: 08/11/2017 - 3:50 pm

PIRSA:17110078  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Measuring the polarization content of gravitational waves with LIGO
Abstract: I will give a brief overview of LIGO’s efforts to test general relativity with gravitational waves. My main focus will be on tests of alternative polarizations.
Date: 08/11/2017 - 3:30 pm

PIRSA:17090073  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Searches for ALPs with Current and Future X-ray Satellites
Abstract: Galaxy clusters represent excellent laboratories to search for Axion-Like Particles (ALPs). They contain magnetic fields which can induce quasi-sinusoidal oscillations in the X-ray spectra of AGNs situated in or behind them. Ultra-deep Chandra observations of the Perseus cluster contain over 5 x 105... read more
Date: 26/09/2017 - 1:00 pm

PIRSA:17070061  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Careers Outside Academia
Date: 26/07/2017 - 5:05 pm

PIRSA:17070040  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Confined Contextuality and Weak Measurement
Date: 25/07/2017 - 10:30 am

PIRSA:17070023  ( MP4 Medium Res , MP3 , PDF ) Which Format?
New physics searches with neutrino-coherent scattering
Date: 21/07/2017 - 2:50 pm

PIRSA:17070009  ( MP4 Medium Res , MP3 , PDF ) Which Format?
What it takes for double beta decay experiments to reach few meV sensitivity (normal mass hierarchy)
Date: 20/07/2017 - 2:00 pm

PIRSA:17070006  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Dark Matter Experiments: Requirements for Lower Thresholds and Improved Sensitivity
Date: 20/07/2017 - 10:45 am

PIRSA:17060111  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Thermal stability and fault-tolerance in symmetry protected topological phases
Abstract: A recent breakthrough in the condensed matter community is the identification and characterization of a rich set of ordered states, known as symmetry protected topological (SPT) phases. These phases are not only fascinating from the perspective of fundamental physics but have also found powerful app... read more
Date: 28/06/2017 - 4:00 pm

PIRSA:17060028  ( MP4 Medium Res , MP3 , PDF ) Which Format?
The thick sandwich problem in (2+1)-dimensional causal dynamical triangulations
Abstract: Causal dynamical triangulations (CDT) is a sum-over-histories approach to quantum gravity which leverages the techniques developed in lattice quantum field theory. In this talk, I discuss the thick sandwich problem in CDT: Given initial and final spacelike hypersurfaces, each with a fixed geometry, ... read more
Date: 01/06/2017 - 4:20 pm
Collection: PI Day

PIRSA:17060020  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Rise of non-perturbative effects below the upper critical dimension
Abstract: Extracting low energy universal data of quantum critical systems is a task whose difficulty increases with decreasing dimension. The increasing strength of quantum fluctuations can be tamed by using renormalization group (RG) schemes based on dimensional regularization close to the upper critical di... read more
Date: 01/06/2017 - 11:00 am
Collection: PI Day

PIRSA:17050087  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Donaldson-Thomas transformations for moduli spaces of local systems on surfaces
Abstract: Kontsevich and Soibelman defined Donaldson-Thomas invariants of a 3d Calabi-Yau category with a stability condition. Any cluster variety gives rise to a family of such categories. Their DT invariants are encapsulated in single formal automorphism of the cluster variety, called the DT-transformation.... read more
Date: 31/05/2017 - 3:30 pm

PIRSA:17050012  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Emergence of Supergroups from Junctions of M-branes
Abstract: We study the boundary conditions in the topologically twisted Chern-Simons matter theories with the Lie 3-algebraic structure. We find that the supersymmetric boundary conditions and the gauge invariant boundary conditions can be unified as the complexified gauge invariant boundary conditions which ... read more
Date: 16/05/2017 - 2:30 pm

PIRSA:17050032  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Positive Representations of Split Real Quantum Groups
Abstract: The notion of Positive Representations is a new research program devoted to the representation theory of split real quantum groups, initiated in a joint work with Igor Frenkel. It is a generalization of the special class of representations considered by J. Teschner for Uq(sl(2,R)) in Liouville theor... read more
Date: 01/05/2017 - 2:00 pm

PIRSA:17040078  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Entangling with Topological Quantum Matter
Abstract: Topological phases of matter serve as one of the most striking examples of the richness and novelty of quantum systems with many degrees of freedom.  In contrast to conventional matter, they are characterized by both non-local properties and non-classical notions such as entanglement.&n... read more
Date: 24/04/2017 - 2:00 pm
Series: Colloquium

PIRSA:17040009  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Testing microscopic discretization
Abstract: What can we say about the spectra of a collection of microscopic variables when only their coarse-grained sums are experimentally accessible? In this paper, using the tools and methodology from the study of quantum nonlocality, we develop a mathematical theory of the macroscopic fluctuations generat... read more
Date: 18/04/2017 - 3:30 pm

PIRSA:17040069  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Random variables, entanglement and nonlocality in infinite > translation-invariant systems
Abstract: We consider the problem of certifying entanglement and nonlocality in one-dimensional translation-invariant (TI) infinite systems when just averaged near-neighbor correlators are available. Exploiting the triviality of the marginal problem for 1D TI distributions, we arrive at a practical characteri... read more
Date: 11/04/2017 - 3:30 pm

PIRSA:17030093  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Testing early Universe physics with upcoming observations
Abstract: Cosmology has seen great progress thanks to precision measurements and is bound to greatly benefit from upcoming Large Scale Structure and Cosmic Microwave Background data. I will point out a number of interesting directions. In particular, I discuss how the microphysics of inflation may be tested i... read more
Date: 28/03/2017 - 11:00 am

PIRSA:17020099  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Harnessing Topological Quantum Matter
Abstract: Topological quantum computing requires phases of matter which host fractionalized excitations that are neither bosons nor fermions. I will present a new route toward realizing such fractionalized phases of matter by literally building on existing topological phases. I will first discuss how existing... read more
Date: 10/03/2017 - 4:00 pm

PIRSA:17030051  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Three-dimensional mirror symmetry: a mathematical perspective
Date: 02/03/2017 - 2:00 pm
Series: Colloquium

PIRSA:17020128  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Boundary Hamiltonian theory for gapped topological phases on an open surface
Abstract: In this talk we propose a Hamiltonian approach to 2+1D gapped topological phases on an open surface with boundary. The bulk part is (Levin-Wen) string-net models arising from a unitary fusion category (can be viewed as Hamiltonian approach to extended Turaev-Viro TQFT), while the boundary Hamilto... read more
Date: 21/02/2017 - 3:30 pm

PIRSA:17010066  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Recovery maps in quantum thermodynamics
Abstract: A research line that has been very active recently in quantum information is that of recoverability theorems. These, roughly speaking, quantify how well can quantum information be restored after some general CPTP map, through particular 'recovery maps'. In this talk, I will outline what thi... read more
Date: 11/01/2017 - 4:00 pm

PIRSA:16110080  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Majorana zero modes in condensed matter: From topological quantum computing milestones to Majorana-dimer models
Abstract: Condensed matter realizations of Majorana zero modes constitute potential building blocks of a topological quantum computer and thus have recently been the subject of intense theoretical and experimental investigation.  In the first part of this talk, I will introduce a new scheme for prepa... read more
Date: 09/12/2016 - 3:30 pm

PIRSA:16110090  ( MP4 Medium Res , MP3 , PDF ) Which Format?
The String Soundscape at Gravitational Wave Detectors
Abstract: In this talk, we explore the possibility of gravitational wave production due to ultra-relativistic bubble wall collisions. This occurs due to a process of post-inflationary vacuum decay that takes place via quantum tunnelling within a warped throat (of Randall-Sundrum type). We emphasise the differ... read more
Date: 29/11/2016 - 1:00 pm

PIRSA:16100052  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Modeling Deviations from Homogeneity in an Inhomogeneous Universe Using Numerical Relativity
Abstract: It has long been wondered to what extent the observable properties of an inhomogeneous universe will be measurably different from a corresponding FLRW model. Here, we use tools from numerical relativity to study the properties of photons traversing an inhomogeneous universe. We evolve the full, unco... read more
Date: 11/10/2016 - 11:00 am

PIRSA:16090056  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Experimental implementation of quantum-coherent mixtures of causal relations
Speaker(s): , Robert Spekkens
Abstract: Understanding the causal influences that hold among the parts of a system is critical both to explaining that system's natural behaviour and to controlling it through targeted interventions. In a quantum world, understanding causal relations is equally important, but the set of possibilities is far ... read more
Date: 23/09/2016 - 4:00 pm

PIRSA:16080045  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Superconducting quantum criticality of Dirac fermions
Abstract: The semimetal-superconductor quantum phase transition of 2D Dirac fermions, such as found on the surface of a topological insulator, is conjectured to exhibit an emergent N=2 supersymmetry, based on a one-loop renormalization group analysis. In this talk I will present further evidence for this conj... read more
Date: 24/08/2016 - 2:15 pm

PIRSA:16080027  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Higher-order interference and phase transformations in operational theories
Date: 04/08/2016 - 2:00 pm

PIRSA:16070044  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Quantum Information and Symmetry
Date: 26/07/2016 - 5:00 pm

PIRSA:16070017  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Gravitational Positive Energy Theorems from Information Inequalities
Date: 19/07/2016 - 5:00 pm

PIRSA:16060120  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Summaries and closing remarks
Speaker(s): , Renate Loll, Adam Frank
Date: 30/06/2016 - 4:30 pm
Collection: Time in Cosmology

PIRSA:16060053  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Features of Sequential Weak Measurements
Abstract: I discuss the outcome statistics of sequential weak measurement of general observables. In sequential weak measurement of canonical variables, without post-selection, correlations yield the corresponding correlations of the Wigner function. Outcome correlations in spin-1/2 sequential weak measurem... read more
Date: 22/06/2016 - 9:45 am

PIRSA:16060039  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Confined contextuality: How specific counterfactual paradoxes in pre- and post-selected Kochen-Specker sets give rise to experimentally observable consequences.
Abstract: The Kochen-Specker (KS) theorem can gives rise to logical paradoxes under pre- and post-selection in which the contextual behavior is confined to specific observables of a system. Weak measurements allow direct experimental observation of the nonclassical behavior of these specific observables. Th... read more
Date: 20/06/2016 - 3:30 pm

PIRSA:16060005  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Machine Learning with Quantum-Inspired Tensor Networks
Abstract: Tensor networks have been very successful for approximating quantum states that would otherwise require exponentially many parameters. I will discuss how a similar compression can be achieved in models used to machine learn data, such as sets of images, by representing the fitting parameters as a... read more
Date: 14/06/2016 - 3:30 pm

PIRSA:16060092  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Primitives of Nonclassicality in the N-qubit Pauli Group
Abstract: Throughout the development of quantum mechanics, the striking refusal of nature to obey classical reasoning and intuition has driven both curiosity and confusion. From the apparent inescapably probabilistic nature of the theory, to more subtle issues such as entanglement, nonlocality, and contextual... read more
Date: 07/06/2016 - 2:00 pm

PIRSA:16050054  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Reduction of the classification of topological insulators and superconductors by quartic interactions
Abstract: I will discuss the stability and breakdown of the topological classification of gapped ground states of non-interacting fermions, the tenfold way, in the presence of quartic fermion-fermion interactions.  In our approach [1], the effects of interactions on the boundary gapless modes are enc... read more
Date: 31/05/2016 - 3:30 pm

PIRSA:16050034  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Disorder in spin liquids
Abstract: Beyond their deceptively featureless ground states, spin liquids are particularly remarkable in the exotic nature of their (fractionalised and gauge charged) excitations. Quenched disorder can be instrumental in nucleating or localising defects with unusual properties, revealing otherwise hidden fea... read more
Date: 12/05/2016 - 10:00 am

PIRSA:16030134  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Effective theories and nucleons: implications for neutrinos, dark matter and atoms
Abstract: The venerable proton continues to play a central role in fundamental particle physics.   Neutrinos scatter from protons in neutrino oscillation experiments, Weakly Interacting Massive Particles (WIMPs) are expected to scatter from protons in dark matter searches, and electrons or m... read more
Date: 31/03/2016 - 1:00 pm

PIRSA:16020114  ( MP4 Medium Res , MP3 , PDF ) Which Format?
On space of integrable quantum field theories
Date: 25/02/2016 - 11:00 am

PIRSA:16020108  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Particles and resonances in Ising Field Theory
Date: 24/02/2016 - 2:00 pm
Series: Colloquium

PIRSA:16020089  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Astrophysical and Cosmological consequences of recent and future kSZ measurements
Abstract: The kinetic Sunyaev-Zel'dovich effect is a direct probe of the distribution and velocity of electrons on cosmological scales.  Recent progress in Cosmic Microwave Background observations allow statistical detections of this subtle effect originating from a number of different tracers popula... read more
Date: 16/02/2016 - 11:00 am

PIRSA:16020086  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Cornering the universal entanglement of CFTs
Abstract: The structure of entanglement can yield new physical insights into strongly interacting quantum critical states. I’ll describe key properties of the entanglement entropy of conformal field theories (CFTs) in 2+1d. In particular, we’ll see that sharp corners in the entangling surface con... read more
Date: 09/02/2016 - 3:30 pm

PIRSA:16020087  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Causality Constraints in Conformal Field Theory
Abstract: In effective field theory, causality fixes the signs of certain interactions.  I will describe how these Lorentzian constraints are encoded in the Euclidean theory, and use the conformal bootstrap to derive analogous causality constraints in CFT. Applied to spinning fields, these constraint... read more
Date: 09/02/2016 - 2:00 pm

PIRSA:16020093  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Interferometry and the Global 21-cm Signal
Abstract: The global redshifted 21-cm radiation background is expected to be a powerful probe of the re-heating and re-ionization of the intergalactic medium. However, its measurement is technically challenging: one must extract the small, frequency-dependent signal from under much brighter and spect... read more
Date: 09/02/2016 - 11:00 am

PIRSA:16010030  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Quantum Clocks
Abstract: Time in quantum mechanics has duly received a lot of attention over the years. Perfect clocks which can turn on/off a particular interaction at a precise time that have been proposed only exist in infinite dimensions and have unphysical Hamiltonians (their spectrum is unbounded fro... read more
Date: 19/01/2016 - 3:30 pm

PIRSA:16010000  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Fast radio bursts as probes of large-scale structure
Abstract: Fast radio bursts (FRBs) are bright, broadband, non-repeating, millisecond flashes of unknown astronomical origin. The dispersion of these bursts by intervening plasma suggests that the sources of the 16 bursts reported to date= are at 0.2<z<1. I will discuss the possibility of using d... read more
Date: 12/01/2016 - 11:00 am

PIRSA:15120010  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Can We Identify the Theory of Dark Matter with Direct Detection?
Abstract: In light of the upcoming Generation 2 (G2) direct-detection experiments attempting to record dark matter scattering with nuclei in underground detectors, it is timely to inquire about their ability to single out the correct theory of dark-matter-baryon interactions, in case a signal is observed. I w... read more
Date: 08/12/2015 - 11:00 am

PIRSA:15110100  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Limits on locality from gravitational dressing
Abstract: In quantum gravity, observables must be diffeomorphism-invariant. Such observables are nonlocal, in contrast with the standard assumption of locality in flat spacetime quantum field theory. I will show how to construct 'gravitationally dressed' observables in linearized gravity that become local in ... read more
Date: 26/11/2015 - 10:30 am

PIRSA:15110061  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Virtual and Mixed Reality and the future of mathematical practice
Abstract: In the summer of 2015, the speaker led a team at Microsoft Research, comprised primarily of research interns from seven universities, to demonstrate a social, ambulatory, Mixed Reality system for the first time.  Each intern developed a preliminary, domain-specific exploration of how such a... read more
Date: 12/11/2015 - 2:30 pm

PIRSA:15110072  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Localization from superselection rules in translation invariant systems
Date: 05/11/2015 - 4:15 pm

PIRSA:15110009  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Kinetic Terms in Massive gravity
Abstract: Is the graviton a truly massless spin-2 particle, or can the graviton have a small mass? If the mass of the graviton is of order the Hubble scale today, it can potentially help to explain the observed cosmic acceleration. Previous attempts to study massive gravity have been spoiled by the fact that ... read more
Date: 03/11/2015 - 11:00 am

PIRSA:15100121  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Learning quantum models for physical and non-physical data
Abstract: In this talk I address the problem of simultaneously inferring unknown quantum states and unknown quantum measurements from empirical data. This task goes beyond state tomography because we are not assuming anything about the measurement devices. I am going to talk about the time and sample complexi... read more
Date: 28/10/2015 - 4:15 pm

PIRSA:15100057  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Unlocking Dark Matter Physics out of Galactic Substructures
Abstract: Despite being ubiquitous throughout the Universe, the fundamental physics governing dark matter remains a mystery. While this physics plays little role in the current evolution of large-scale cosmic structures, it did have a major impact in the early epochs of the Universe on the evolution of cosmol... read more
Date: 27/10/2015 - 11:00 am

PIRSA:15100110  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Spin--Statistics and Categorified Galois Groups
Date: 23/10/2015 - 10:30 am

PIRSA:15100026  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Superfluid Dark Matter

I will talk about a novel theory of dark matter superfluidity that matches the success of LCDM model on cosmological scales while simultaneously reproducing the MOND phenomenology on galactic scales.

Date: 20/10/2015 - 11:00 am

PIRSA:15090063  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Numerical spectral geometry
Date: 12/09/2015 - 5:00 pm

PIRSA:15090058  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Random non-commutative geometries
Date: 12/09/2015 - 11:30 am

PIRSA:15090009  ( MP4 Medium Res , MP3 , PDF ) Which Format?
An algebraic approach to the problem of time
Abstract: An algebraic view allows one to compute properties of physical states without having to introduce an explicit Hilbert space. In relational systems without absolute time, a state cannot be completely positive once a choice for a (possibly local) internal time has been made. A more general class of `a... read more
Date: 03/09/2015 - 2:30 pm

PIRSA:15080078  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Diffeomorphism-invariant observables and nonlocality
Abstract: In a theory of gravity, observables must be diffeomorphism-invariant. Such observables are nonlocal, in contrast with the usual formulation of local quantum field theory. Working to leading order in Newtons constant G, I'll describe a construction of diffeomorphism-invariant observables for a scalar... read more
Date: 20/08/2015 - 4:30 pm

PIRSA:15080073  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Gong Show
Date: 19/08/2015 - 4:30 pm

PIRSA:15080116  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Using anomaly tests to restrict crystal symmetry fractionalization in Z_2 and chiral spin liquids
Abstract: Using the method of flux fusion anomaly test recently developed by M. Hermele and X. Chen (arXiv:1508.00573), we show that the possible ways of fractionalize crystal symmetry is greatly restricted if we assume the spin liquid has an SU(2) spin rotation symmetry and the spinon carries a half-integer ... read more
Date: 11/08/2015 - 11:00 am

PIRSA:15080014  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Abstract: TBA
Date: 11/08/2015 - 10:40 am

PIRSA:15060025  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Welcome & Overview
Date: 25/06/2015 - 9:00 am

PIRSA:15060045  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Welcome to Convergence - Opening Panel: Physics Today
Date: 22/06/2015 - 9:00 am
Collection: Convergence

PIRSA:15060004  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Economic inequality from statistical physics point of view - Victor Yakovenko
Abstract: Similarly to the probability distribution of energy in physics, the probability distribution of money among the agents in a closed economic system is also expected to follow the exponential Boltzmann-Gibbs law, as a consequence of entropy maximization.  Analysis of empirical data shows that... read more
Date: 10/06/2015 - 11:00 am

PIRSA:15050128  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Quantum non-commutative geometry

The talk will discuss my attempts to define quantum geometry (and hence quantum gravity) using non-commutative geometries and the interesting mathematical structures that emerge.

Date: 28/05/2015 - 2:30 pm

PIRSA:15050026  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Resource theories of knowledge
Abstract: Inspired by quantum information approaches to thermodynamics, we introduce a general framework for resource theories, from the perspective of subjective agents. First we formalize a way to think of subjective knowledge through what we call specification spaces, where states of knowledge (or specific... read more
Date: 20/05/2015 - 4:00 pm

PIRSA:15050042  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Displaced vertices from dark matter freeze-in
Abstract: Freeze-in is a general and calculable mechanism for dark matter production in the early universe. Assuming a standard cosmological history, such a framework predicts metastable particles with a lifetime generically too long to observe their decays in a collider environment. In this talk I will rep... read more
Date: 08/05/2015 - 12:30 pm

PIRSA:15050118  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Electric fields and quantum wormholes
Abstract: A classical Einstein-Rosen bridge changes the topology of spacetime,allowing (for example) electric field lines to penetrate it. It has recently been suggested that in the bulk of a theory of quantum gravity, the quantum entanglement of ordinary perturbative quanta should be viewed as creating a qua... read more
Date: 08/05/2015 - 10:00 am

PIRSA:15040067  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Analog Duality
Abstract: I will discuss a new duality between strongly coupled and weakly coupled condensed matter systems. It can be obtained by combining the gauge-gravity duality with analog gravity. In my talk I will explain how one arrives at the new duality, what it can be good for, and what questions this finding rai... read more
Date: 30/04/2015 - 2:30 pm

PIRSA:15040085  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Interacting surface states of topological insulators and superfluids
Abstract: The standard theory of topological insulators and superfluids (or superconductors) assumes that the fermionic elementary excitations in these systems – electrons in the insulator and Bogoliubov quasiparticles in the superfluid – do not interact with one another. In this talk I will discuss exten... read more
Date: 28/04/2015 - 3:30 pm

PIRSA:15040130  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Analytic Bootstrap Bounds
Date: 16/04/2015 - 10:00 am

PIRSA:15040128  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Modular invariance and holographic CFTs
Abstract: Modular invariance plays an important role in AdS3/CFT2 holography. I discuss the structure of non-holomorphic CFT partition functions, namely in what sense the light spectrum determines the heavy spectrum and how to construct example partition functions using Poincare series. This yields necessary ... read more
Date: 15/04/2015 - 11:00 am

PIRSA:15040121  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Symplectic automorphisms of some hyperk"ahler manifolds
Date: 13/04/2015 - 2:00 pm

PIRSA:15040103  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Superluminalities in Galileon theories
Date: 09/04/2015 - 4:30 pm

PIRSA:15040102  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Subluminal Vainshtein Screening in Massive Gravity
Abstract: I will discuss the Vainshtein mechanism in massive gravity. I will show that the spherically symmetric backgrounds that were believed to have superluminal sound speed are in fact unstable. Instead, there is a new class of phenomenologically relevant solutions with stable and subluminal perturbations... read more
Date: 09/04/2015 - 3:15 pm

PIRSA:15040100  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Superluminalities in Galileon theories
Date: 09/04/2015 - 11:00 am

PIRSA:15030107  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Galileons and their generalizations

Galileons are higher-derivative effective field theories with curious properties which have attracted much recent interest among cosmologists.  I will review their origins, their properties, their generalizations, and some recent developments.

Date: 25/03/2015 - 2:00 pm
Series: Colloquium

PIRSA:15030076  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Splitting processes of membranes in the pp-wave matrix model and three dimensional analog of Riemann surfaces
Abstract: The talk will be based on a work in progress with Stefano Kovacs (Dublin IAS) and Yuki Sato (Wits University). In a previous work (arxiv:1310.0016) we have shown that, in the M-theory regime (large N with the Chern-Simon level k fixed) of the duality between ABJM theory and M-theory on AdS4 x S7... read more
Date: 03/03/2015 - 4:00 pm

PIRSA:15020115  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Doing Physics with Shape Dynamics
Abstract: Shape Dynamics is a theory of gravity which replaces relativity of simultaneity for spatial conformal invariance, maintaining the same degree of symmetry of General Relativity while avoiding some of its shortcomings. In SD several kinds of singularities of GR become unphysical gauge artefacts, an... read more
Date: 25/02/2015 - 2:00 pm
Series: Colloquium

PIRSA:15020131  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Exploring new physics through double Higgs production
Abstract: The Higgs boson was discovered at the LHC more than two years ago. So far, the LHC data is consistent with the Standard Model (SM) predictions. Given its increased rate in the next run of the LHC with a center-of-mass energy of 14 TeV, double Higgs production will become an important channel in ... read more
Date: 20/02/2015 - 3:30 pm

PIRSA:15020085  ( MP4 Medium Res , MP3 , PDF ) Which Format?
UV Properties of Galileons
Abstract: It is well known that S-matrix Analyticity, Lorentz invariance and Unitarity place strong constraints on whether Effective Field Theories can be UV completed. A large class of gravitational field theories such as Massive Gravity and DGP inspired braneworld models contain as limits Galileon theories ... read more
Date: 17/02/2015 - 11:00 am

PIRSA:15020081  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Creating an inclusive climate: Steps toward institutional change
Abstract: In this talk I will outline the process of institutional change begun at the University of Michigan in 2001 and continuing today. This will include discussion of a range of institutional efforts to improve hiring, recruitment, climate and leadership that was focused on creating a more diverse and in... read more
Date: 11/02/2015 - 2:00 pm
Series: Colloquium

PIRSA:15020088  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Cosmology in Massive GravityLand
Abstract: The last years have seen a renewed interest in theories of massive gravity. They represent an infra-red modification of gravity where the gravitational force weakens at very large scales. Heuristically, they provide the playground to understand a possible modification of GR which could potentially p... read more
Date: 10/02/2015 - 11:00 am

PIRSA:15010074  ( MP4 Medium Res , MP3 , PDF ) Which Format?
A ΛCDM Bounce Scenario
Abstract: We study a contracting universe composed of cold dark matter and radiation, and with a positive cosmological constant. Assuming that loop quantum cosmology captures the correct high-curvature dynamics of the space-time, we calculate the spectrum of scalar and tensor perturbations after the bounce, a... read more
Date: 21/01/2015 - 4:00 pm

PIRSA:14120042  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Viscous and Thermal Transport in Topological Phases
Abstract: One hallmark of topological phases with broken time reversal symmetry is the appearance of quantized non-dissipative transport coefficients, the archetypical example being the quantized Hall conductivity in quantum Hall states. Here I will talk about two other non-dissipative transport coefficients ... read more
Date: 12/12/2014 - 1:00 pm

PIRSA:14120029  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Different Strategies for Quantum Adiabatic Optimization, and the Computational Power of Simulated Quantum Annealing
Abstract: Quantum Adiabatic Optimization proposes to solve discrete optimization problems by mapping them onto quantum spin systems in such a way that the optimal solution corresponds to the ground state of the quantum system. The standard method of preparing these ground states is using the adiabatic theorem... read more
Date: 03/12/2014 - 4:00 pm

PIRSA:14120021  ( MP4 Medium Res , MP3 , PDF ) Which Format?
DAEdALUS and Dark Matter
Abstract: In the search for dark matter, neutrino experiments can play a key role by doubling as dark matter production and detection experiments. I will describe how the proposed DAEdALUS decay-at-rest neutrino experiment can be used to search for MeV-scale dark matter, with particular emphasis on dark matte... read more
Date: 03/12/2014 - 11:00 am

PIRSA:14120034  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Braiding statistics of loops in three spatial dimensions
Abstract: In two spatial dimensions, it is well known that particle-like excitations can come with fractional statistics, beyond the usual dichotomy of Bose versus Fermi statistics. In this talk, I move one dimension higher to three spatial dimensions, and study loop-like objects instead of point-like particl... read more
Date: 02/12/2014 - 3:30 pm

PIRSA:14120016  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Implications of computer science principles for quantum physics
Abstract: The Church-Turing thesis is one of the pillars of computer science; it postulates that every classical system has equivalent computability power to the so-called Turing machine. While this thesis is crucial for our understanding of computing devices, its implications in other scientific fields have ... read more
Date: 02/12/2014 - 3:30 pm

PIRSA:14110158  ( MP4 Medium Res , MP3 , PDF ) Which Format?
CFT/Gravity Correspondence on the Isolated Horizon
Abstract: A quantum isolated horizon can be modeled by an SU(2) Chern-Simons theory on a punctured 2-sphere. We show how a local 2-dimensional conformal symmetry arises at each puncture inducing an infinite set of new observables localized at the horizon which satisfy a Kac-Moody algebra. By means of the isol... read more
Date: 27/11/2014 - 2:30 pm

PIRSA:14110182  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Cosmic Flows: cosmology and astrophysics from galaxy velocities
Abstract: Velocity fields are a powerful probe of structure formation and the energy content of our Universe. Additionally, the motion of ionized gas on intermediate scales can be used to measure the clustering of baryons and shed light on galaxy formation and feedback mechanisms.  ... read more
Date: 25/11/2014 - 11:00 am

PIRSA:14110132  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Fractionalization from Crystallography
Abstract: A featureless insulator is a gapped phase of matter that does not exhibit fractionalization or other exotic physics, and thus has a unique ground state. The classic albeit non-interacting example is an electronic band insulator. A standard textbook argument tells us that band insulators require an e... read more
Date: 18/11/2014 - 3:30 pm

PIRSA:14110105  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Deblurring Sgr A* Images
Abstract: Scattering in the tenuous interstellar plasma blurs the image of Sgr A*. This effect decreases steeply with increasing frequency and becomes subdominant to the intrinsic emission structure at wavelengths close to a millimeter. I will discuss recent work that demonstrates how we can invert the blurri... read more
Date: 14/11/2014 - 10:45 am
Collection: EHT 2014

PIRSA:14110107  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Phasing ALMA
Date: 13/11/2014 - 3:45 pm
Collection: EHT 2014

PIRSA:14110139  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Detection and Implications of Horizon-Scale Polarization in Sgr A*
Abstract: The Event Horizon Telescope has measured compact emission in Sgr A* and M87 at resolutions comparable to their event horizons. Polarimetry with the EHT enables a powerful extension of this work, mapping magnetic field structures via the highly polarized synchrotron emission that is thought to domina... read more
Date: 10/11/2014 - 2:55 pm
Collection: EHT 2014

PIRSA:04040002  ( MP4 Medium Res , MP3 , PDF ) Which Format?
The Art of Mathematics
Date: 07/04/2004 - 7:00 pm
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