Bounding Transport and Chaos in Condensed Matter and Holography

Europe/Stockholm
122:026 (Nordita, Stockholm)

122:026

Nordita, Stockholm

Blaise Goutéraux, Erez Berg (University of Chicago), Lárus Thorlacius (Iceland U. and Stockholm U.), Sean Hartnoll (Stanford University)
Description

Venue

Nordita, Stockholm, Sweden

Scope

This program will explore recent developments in describing the dynamics of strongly-coupled quantum systems using the notion of fundamental, quantum bounds on transport, and their interplay with quantum chaos. Experiments, as well as theoretical results coming from quantum field theory, lattice models and gauge/gravity duality, hint that the late time dynamics of these systems is governed by a Planckian timescale, the shortest allowed by quantum mechanics. This timescale provides a bound on the growth of chaos and the scrambling of quantum information, saturated in theories with Einstein holographic duals. From the point of view of thermoelectric transport, this timescale may bound the diffusive processes which underpin the ubiquitous T-linear resistivity of the bad metallic phase of high Tc superconductors and other unconventional materials. Diffusive transport also emerges in exactly solvable, quantum chaotic models like the Sachdev-Ye-Kitaev model.

By bringing together international leaders in condensed matter and high energy physics, we aim at enhancing our current understanding by combining experimental results and the various theoretical, non-perturbative approaches to these problems. Participants will include experts in thermoelectric transport experiments, hydrodynamics, gauge/gravity duality, numerical and analytic condensed matter theory and conformal field theory.

[Timetable - available from start of the program]

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Application for participation to this program is open

Confirmed invited participants include

  • Kamran Behnia (ESPCI, Paris)
  • Mike Blake (MIT)
  • Sera Cremonini (Lehigh)
  • Richard Davison (Harvard)
  • Anatoly Dymarsky (Kentucky)
  • Aristomenis Donos (Durham)
  • Johannes Gooth (MPI Dresden)
  • Saso Grozdanov (MIT)
  • Nigel Hussey (Radboud U., Nijmegen)
  • Nabil Iqbal (Durham)
  • Kristan Jensen (San Francisco State U)
  • Aharon Kapitulnik (Stanford)
  • Elias Kiritsis (Crete and APC, Paris)
  • Pavel Kovtun (Victoria)
  • Andy Lucas (Stanford)
  • John McGreevy (UC San Diego)
  • Andrew Mackenzie (MPI Dresden)
  • Christiana Pantelidou (Durham)
  • Tomaz Prosen (U. of Ljubljana)
  • Thomas Scaffidi (Berkeley)
  • Koenraad Schalm (Leiden)
  • Peter Schauss (Princeton)
  • Effrat Shimshoni (Bar-Ilan)
  • Andrei Starinets (Oxford)
  • Joseph Thywissen (Toronto)

Contact

cmh2018@nordita.org

Accommodation

Please be aware that unfortunately, scammers sometimes approach participants claiming to be able to provide accommodation and asking for credit card details. Please do not give this information to them. For successful applicants, Nordita will be in touch via email regarding accommodation. If you are in any doubt about the legitimacy of an approach, please get in contact with the organisers.

Sponsored by:

Nordita Swedish Research Council ICAM-I2CAM

Participants
  • Aavishkar Patel
  • Ady Stern
  • Aharon Kapitulnik
  • Alexander Krikun
  • Alexander Krikun
  • Anatoly Dymarsky
  • Andrei Starinets
  • Andrew Lucas
  • Andrew Mackenzie
  • Anna Karlsson
  • Aristomenis Donos
  • Aruna Rajagopal
  • Aurelio Romero Bermúdez
  • Blaise Goutéraux
  • Bo Sundborg
  • Christiana Pantelidou
  • Connie Mousatov
  • Daniel Arean
  • Daniel Fernandez
  • Daniel Fernandez
  • David Rodriguez
  • Dmitry Bagrets
  • Efrat Shimshoni
  • Elias Kiritsis
  • Erez Berg
  • Erik van Heumen
  • Ioannis Matthaiakakis
  • John McGreevy
  • Jonathan Lindgren
  • Joseph Thywissen
  • Julia Steinberg
  • Julius Engelsöy
  • Junggi Yoon
  • Kamran Behnia
  • Kenta Suzuki
  • Koenraad Schalm
  • Kristan Jensen
  • Laraña Aragón Jorge
  • Larus Thorlacius
  • Louise Anderson
  • Luca Delacretaz
  • Lukas Schneiderbauer
  • Marcus Aronsson
  • Matthew Roberts
  • Michael Blake
  • Moshe Rozali
  • Nabil Iqbal
  • Nick Poovuttikul
  • Nicolas Delporte
  • Nigel Hussey
  • Niko Jokela
  • Oscar Henriksson
  • Pavel Kovtun
  • Peter Schauss
  • Petter Säterskog
  • Richard Davison
  • Saso Grozdanov
  • Sean Hartnoll
  • Sera Cremonini
  • Thomas Scaffidi
  • Tomaz Prosen
  • Ulf Gran
  • Valentina Giangreco Puletti
  • Vedika Khemani
  • Victoria Martin
  • Viktor Svensson
  • Watse Sybesma
  • Xiaoyu Wang
  • Xizhi Han
  • Ya-Wen Sun
  • Yochai Werman
  • Zhuo-Yu Xian
    • 09:30 11:00
      Registration and coffee 1h 30m 122:026

      122:026

      Nordita, Stockholm

    • 11:00 12:00
      Planckian Bound on the Decay of Simple Operators 1h 122:026

      122:026

      Nordita, Stockholm

      I propose a generic Planckian bound on the lifetime of "simple" operators. This is related -- but not identical -- to the Planckian bound on quantum many-body chaos. This proposal reconciles the intuition that quantum dynamics (and chaos) is bounded by the Planckian time scale with the behavior of free theories, disordered metals in the low temperature limit, and disorder-driven metal-insulator transitions.
      Speaker: Andrew Lucas (Stanford)
      Slides
    • 14:00 14:30
      Space-Time in the SYK Model 30m 122:026

      122:026

      Nordita, Stockholm

      Speaker: Kenta Suzuki (Ecole Polytechnique)
      Slides
    • 14:30 15:00
      Higher-form global symmetry in Theory of elasticity and holographic model with transverse sound 30m 122:026

      122:026

      Nordita, Stockholm

      Speaker: Nick Poovuttikl (Iceland)
      Slides
    • 11:00 12:00
      Fine Grained Chaos in AdS2 and AdS3 1h 122:026

      122:026

      Nordita, Stockholm

      Speaker: Moshe Rozali (UBC)
      Slides
    • 14:00 15:00
      Slow relaxation and diffusion in holographic quantum critical phases 1h 122:026

      122:026

      Nordita, Stockholm

      In many-body quantum systems with strong interactions, the timescale governing transport is typically expected to be short and set by the inverse temperature. For example, in many holographic quantum critical phases of matter the thermal diffusivity (in appropriate units) is set by the inverse temperature. However, there are a simple class of such phases where this is not the case. I will discuss these phases and show that they have a collective excitation whose lifetime is parametrically longer than the inverse temperature. The lifetime of this excitation is enhanced due to its sensitivity to an irrelevant deformation, and I will show that it is this lifetime which ultimately governs the thermal diffusivity in these phases.
      Speaker: Richard Davison (Harvard)
      Slides
    • 18:00 20:00
      Reception 2h 122:026

      122:026

      Nordita, Stockholm

    • 10:00 11:00
      Origin of macroscopic Thouless (diffusion) time from the underlying quantum mechanics 1h 122:026

      122:026

      Nordita, Stockholm

      Speaker: Anatoly Dymarsky (Kentucky)
      Slides
    • 11:00 11:30
      Coffe break 30m 122:026

      122:026

      Nordita, Stockholm

    • 11:30 12:30
      What is a transport coefficient? 1h 122:026

      122:026

      Nordita, Stockholm

      Speaker: Pavel Kovtun (University of Victoria)
      Slides
    • 11:00 12:00
      A theory of reparameterizations for AdS3 gravity 1h 122:026

      122:026

      Nordita, Stockholm

      Speaker: Kristan Jensen (San Francisco State University)
      Slides
    • 14:00 14:30
      Locality Bound for Dissipative Quantum Transport 30m 122:026

      122:026

      Nordita, Stockholm

      Speaker: Xizhi Han (Stanford)
      Slides
    • 14:30 15:00
      Holographic Strange Insulators from Pinning of Spontaneous Superstructures 30m 122:026

      122:026

      Nordita, Stockholm

      When one considers the interplay between spontaneous and explicit symmetry breaking in finite charge density systems, one can observe the metal-insulator phase transition when the spontaneous superstructure is formed on top of the explicitly broken state. This goes under the name of "pinning of charge density wave" and eventually can lead to the formation of a Mott insulator, when the pinning gets strong. I will discuss the examples of this phenomenon in holographic models with periodic inhomogeneous and helical homogeneous lattices. The insulating state formed in these holographic models turns out to be quite interesting: firstly it is gapless and inherits the scaling features of the near horizon geometry, secondly, it demonstrates strong suppression of conductivity even for weak explicit translational symmetry breaking, which goes beyond the usual picture of the conductivity being governed by the momentum relaxation rate.
      Speaker: Alexander Krikun (Leiden University)
      Slides
    • 11:00 12:00
      Holographic Fermions in Striped Superconductors 1h 122:026

      122:026

      Nordita, Stockholm

      In this talk I will discuss a holographic model of a striped superconductor, in which a U(1) symmetry and translational invariance are broken spontaneously at the same time. This construction provides a concrete example of intertwined orders in holography, and realizes certain key features of pair density wave order. I will also examine the behavior of a probe fermion in this background and the formation and evolution of a Fermi surface in the corresponding PDW phase, in the presence of an explicit UV lattice. The structure of the Fermi surface is very sensitive to the strength of the lattice. In particular, strong lattice effects lead to a broadening of the spectral weight peaks and a gradual disappearance of the Fermi surface along the symmetry breaking direction. The resulting Fermi surface appears to consist of detached segments reminiscent of Fermi arcs.
      Speaker: Sera Cremonini (Lehigh University)
      Slides
    • 09:00 10:00
      Registration and coffee 1h 122:026

      122:026

      Nordita, Stockholm

    • 10:00 10:30
      Bad metallic transport in a modified Hubbard model 30m 122:026

      122:026

      Nordita, Stockholm

      Strongly correlated metals often display anomalous transport, including T-linear resistivity above the Mott-Ioffe-Regel limit. We introduce a tractable microscopic model for bad metals, by supplementing the well-known Hubbard model --- with hopping t and on-site repulsion U --- with a `screened Coulomb' interaction between charge densities that decays exponentially with spatial separation. This interaction lifts the extensive degeneracy in the spectrum of the t=0 Hubbard model, allowing us to fully characterize the small t electric, thermal and thermoelectric transport in our strongly correlated model. Throughout the phase diagram we observe T-linear resistivity above the Mott-Ioffe-Regel limit, together with strong violation of the Weidemann-Franz law and a large thermopower that can undergo sign change.
      Speaker: Connie Mousatov (Stanford)
      Slides
    • 10:30 11:00
      Many body chaos in QED3 30m 122:026

      122:026

      Nordita, Stockholm

      Speaker: Julia Steinberg (Harvard)
    • 14:00 15:00
      Quantum Chaos, hydrodynamics and black hole scrambling 1h FA32 (Albanova)

      FA32 (Albanova)

      Nordita, Stockholm

      Speaker: Koenraad Schalm (Leiden University)
      Slides
    • 10:00 11:00
      Quantum chaos in a Rydberg atom system 1h FB42 (Albanova)

      FB42 (Albanova)

      Nordita, Stockholm

      Speaker: Yochai Werman (U. C. Berkeley)
      Slides
    • 18:00 20:00
      Reception 2h 122:026

      122:026

      Nordita, Stockholm

    • 10:00 11:00
      Observation of Quantum Bounds in Spin Diffusivity 1h FB42 (Albanova)

      FB42 (Albanova)

      Nordita, Stockholm

      Speaker: Joseph Thywissen (University of Toronto)
      Slides
    • 14:00 15:00
      Thermal Transport Beyond the Mott-Ioffe-Regel Limit 1h FB42 (Albanova)

      FB42 (Albanova)

      Nordita, Stockholm

      The Boltzmann-Drude picture of electronic transport ceases to be valid when the electron mean-free-path becomes shorter than the Fermi wavelength. The Mott-Ioffe-Regel limit is defined where the two lengths are equal, and beyond it metallic transport becomes incoherent. Most experimental works have focused on the electronic transport, with the host crystal providing a phonon background. Here we report thermal diffusivity measurements that, together with the resistivity, give a full account of transport of charge and entropy. Utilizing a high-resolution photothermal apparatus, we study the thermal diffusivity of several cuprate systems in the regime where the quasiparticle picture fails for both electron and phonons. The inverse diffusivity at high temperature can be fitted with a temperature-linear form, where the slope term is set by a unique velocity and a Planckian relaxation time ~h/kBT, The constant term represents a quantum-diffusion constant separating incoherent transport from a regime with well-defined quasiparticles.
      Speaker: Aharon Kapitulnik (Stanford)
      Slides
    • 11:00 11:45
      Hydrodynamic electron flows and Hall viscosity 45m FB42 (Albanova)

      FB42 (Albanova)

      Nordita, Stockholm

      In metallic systems of small enough size and sufficiently strong momentum-conserving scattering, the viscosity of the electron gas can become the dominant process governing transport. In this regime, momentum is a long-lived quantity whose evolution is described by an emergent hydrodynamical theory. Furthermore, breaking time-reversal symmetry leads to the appearance of an odd component to the viscosity called the Hall viscosity, which has attracted considerable attention recently due to its quantized nature in gapped systems but still eludes experimental confirmation. Based on microscopic calculations, we discuss how to measure the effects of both the even and odd components of the viscosity using hydrodynamic electronic transport in mesoscopic samples under applied magnetic fields.
      Speaker: Thomas Scaffidi (U. C. Berkeley)
      Slides
    • 11:45 12:30
      Experimental Searches for Electron Hydrodynamics 45m FB42 (Albanova)

      FB42 (Albanova)

      Nordita, Stockholm

      Speaker: Andrew Mackenzie (Max Planck Institute for Chemical Physics of Solids)
      Slides
    • 14:00 15:00
      Nernst effect near a Superconductor-Insulator transition 1h FB42 (Albanova)

      FB42 (Albanova)

      Nordita, Stockholm

      Speaker: Efrat Shimshoni (Bar-Ilan University)
      Slides
    • 09:30 10:30
      Pole-skipping 1h FB42 (Albanova)

      FB42 (Albanova)

      Nordita, Stockholm

      Speaker: Saso Grozdanov (MIT)
      Slides
    • 10:30 11:00
      Coffe break 30m FB42 (Albanova)

      FB42 (Albanova)

      Nordita, Stockholm

    • 11:00 11:30
      Hydrodynamics with fluctuating broken translations 30m FB42 (Albanova)

      FB42 (Albanova)

      Nordita, Stockholm

      Speaker: Anna Karlsson (Institute for Advanced Study)
      Slides
    • 11:30 12:00
      Topological semimetals from holography 30m FB42 (Albanova)

      FB42 (Albanova)

      Nordita, Stockholm

      Speaker: Ya-Wen Sun (University of Chinese Academy of Sciences)
      Slides
    • 09:00 10:00
      Registration and coffee 1h FB42 (Albanova)

      FB42 (Albanova)

      Nordita, Stockholm

    • 10:00 10:30
      Introduction 30m FB42 (Albanova)

      FB42 (Albanova)

      Nordita, Stockholm

      Speaker: Sean Hartnoll (Stanford)
    • 10:30 11:30
      Bad Metallic Transport in a Cold Atom Fermi-Hubbard System 1h FB42 (Albanova)

      FB42 (Albanova)

      Nordita, Stockholm

      Probing the charge transport properties of quantum materials can reveal their unique microscopic properties. Weakly interacting systems such as Fermi liquids are well described by semiclassical Boltzmann transport, but strong interactions blur the particle-like behavior of charge carriers causing this picture to break down. Transport in strongly interacting quantum systems is poorly understood, but exhibits interesting phenomenology in many real materials. In our work, we experimentally study charge conductivity in the Fermi-Hubbard model. Using a quantum gas microscope, we impose a density modulation on a uniform system of ultracold 6Li in a 2D optical lattice and observe this modulation decay due to charge diffusion. We find that the decay can be described by a hydrodynamic model and extract the momentum relaxation rate and diffusion constant for a range of temperatures. We determine the conductivity from the diffusion constant using the Nernst-Einstein relation. We observe that the resistivity scales linearly with temperature and shows no sign of saturation for temperatures ranging from near the super-exchange energy scale to the bandwidth. These anomalous behaviors are characteristic of bad metals.
      Speaker: Peter Schauss (Princeton University)
      Slides
    • 13:30 14:30
      A quantum hydrodynamical description for chaos 1h FB42 (Albanova)

      FB42 (Albanova)

      Nordita, Stockholm

      Rapid progress in calculating out-of-time ordered correlation functions in holographic theories and solvable models like the Sachdev-Ye-Kitaev model has led to new characterisations of chaos in quantum many-body systems. However, a unified description of this behaviour is so far lacking. Here I will discuss a recent proposal for an effective field theory description of chaos in terms of `quantum hydrodynamics'. In this approach the scrambling of quantum information (i.e. chaos) arises from interactions between generic operators and hydrodynamic fluctuations.
      Speaker: Michael Blake (MIT)
      Slides
    • 10:30 11:30
      Hall number and other anomalies in the strange metal phase of overdoped cuprates 1h 122:026

      122:026

      Nordita, Stockholm

      Speaker: Nigel Hussey (High Field Magnet Laboratory, Nijmegen)
      Slides
    • 13:30 14:30
      Spectral form factor in an exactly solvable model of many body quantum chaos in 1+1 D 1h FB42 (Albanova)

      FB42 (Albanova)

      Nordita, Stockholm

      Speaker: Tomaz Prosen (University of Ljubljana)
      Slides
    • 18:00 20:30
      Reception 2h 30m 122:026

      122:026

      Nordita, Stockholm

    • 10:00 11:00
      Phonons' Poiseuille flow 1h 122:026

      122:026

      Nordita, Stockholm

      Speaker: Kamran Behnia (ESPCI, France)
      Slides
    • 15:00 16:00
      Operator spreading and the emergence of dissipation in unitary dynamics with conservation laws 1h 122:026

      122:026

      Nordita, Stockholm

      I will discuss the “scrambling” of local quantum information in chaotic quantum many-body systems in the presence of a locally conserved quantity like charge or energy that moves diffusively. The interplay between conservation laws and scrambling sheds light on the mechanism by which unitary quantum dynamics, which is reversible, gives rise to diffusive hydrodynamics, which is a dissipative process. Our results are obtained by examining the dynamics of operator spreading under unitary time evolution in a random quantum circuit model that is constrained to have a conservation law. We find that a generic spreading operator spreads ballistically with a front that moves at a “butterfly speed”, but develops a power law “tail” behind its leading ballistic front due to the slow dynamics of the conserved component of the operator. This structure implies that the out-of-time-order commutator (OTOC) between two initially spatially separated operators grows sharply upon the arrival of the ballistic front but, in contrast to systems with no conservation laws, it develops a diffusive tail and approaches its asymptotic late-time value only as a power of time instead of exponentially. I will also present these results within an effective hydrodynamic description which contains multiple coupled diffusion equations.
      Speaker: Vedika Khemani (Harvard)
      Slides
    • 10:30 11:30
      Bounds on transport and thermalization from positivity 1h 122:026

      122:026

      Nordita, Stockholm

      Speaker: Luca Delacrétaz (Stanford)
      Slides
    • 13:30 14:30
      Strange metals from local quantum chaos 1h 122:026

      122:026

      Nordita, Stockholm

      Speaker: John Mcgreevy (UCSD)
      Slides
    • 10:30 11:30
      Towards a comprehensive test of holographic principles in cuprates 1h 122:026

      122:026

      Nordita, Stockholm

      Speaker: Erik Van Heumen (van der Waals-Zeeman institute, Amsterdam)
    • 09:00 10:30
      Registration and coffee 1h 30m 122:026

      122:026

      Nordita, Stockholm

    • 10:30 11:30
      Quantum fluctuations in real and complex Sachdev-Ye-Kitaev models 1h 122:026

      122:026

      Nordita, Stockholm

      Speaker: Dmitry Bagrets (Institute for Theoretical Physics, University of Cologne)
      Slides
    • 13:30 14:30
      Applications of higher form symmetries 1h 122:026

      122:026

      Nordita, Stockholm

      Speaker: Nabil Iqbal (Durham University)
      Slides
    • 10:30 11:30
      Solvable models of correlated metals with interactions and disorder, and their transport properties 1h 122:026

      122:026

      Nordita, Stockholm

      Despite much theoretical effort, there is no complete theory of the “strange” metal phase of the high temperature superconductors, and its linear-in-temperature resistivity. This phase is believed to be a strongly-interacting metallic phase of matter without fermionic quasiparticles, and is virtually impossible to model accurately using traditional perturbative field-theoretic techniques. Recently, progress has been made using large-N techniques based on the solvable Sachdev-Ye-Kitaev (SYK) model, which do not involve expanding about any weakly-coupled limit. I will describe constructions of solvable models of strange metals based on SYK-like large-N limits, which can reproduce some of the experimentally observed features of strange metals and adjoining phases. These models, and further extensions, could possibly pave the way to developing a controlled theoretical understanding of the essential building blocks of the electronic state in correlated-electron superconductors near optimal doping.
      Speaker: Aavishkar Patel (Harvard)
      Slides
    • 13:30 14:30
      Towards bad metallic transport from holographic failed insulators 1h 122:026

      122:026

      Nordita, Stockholm

      Speaker: Daniel Arean (IFT, Madrid)
      Slides
    • 18:00 20:30
      Reception 2h 30m 122:026

      122:026

      Nordita, Stockholm

    • 09:30 10:30
      Interpolating between strong and weak coupling in thermal QFTs with gravity duals 1h 122:026

      122:026

      Nordita, Stockholm

      Speaker: Andrei Starinets (University of Oxford)
      Slides
    • 11:00 11:30
      Electrical transport near Ising-nematic QCP 30m 122:026

      122:026

      Nordita, Stockholm

      An electronic nematic order spontaneously breaks the rotation symmetry of many body system, making various physical properties anisotropic. It has been observed in various systems, in particular the cuprate and iron-based high temperature superconductors. In the vicinity of a nematic quantum critical point — achieved by tuning some external parameter such as pressure or doping — the physics is described by that of low-frequency long-wavelength order parameter fluctuations coupled to a Fermi surface. However, due to the momentum-conserving nature of the induced electron-electron interaction, the temperature dependence of the resistivity near an Ising nematic QCP remains unclear. In this talk, we shed light on the problem by incorporating disorder and Umklapp process into the low-energy theory. Our work can be viewed as solving an extended Boltzmann equation, with a collision integral that accounts for complicated multi-particle scattering processes important near the QCP.
      Speaker: Xiaoyu Wang (James Frank Institute, University of Chicago)
      Slides
    • 11:30 12:00
      Entanglement entropy in generalised Quantum Lifshitz models 30m 122:026

      122:026

      Nordita, Stockholm

      n the initial part of the talk I will review the generalised quantum Lifshitz models, that is free field theories with Lifshitz scaling symmetry which extend the (2+1)-dimensional quantum Lifshitz model to higher dimension. As in the lower dimensional case the ground state wave functional is invariant under spatial conformal symmetries, whenever the dynamical critical exponent is equal to the number of spatial dimensions. Thanks to this feature, they provide us with simple models for non-relativistic critical theories, suitable to investigate the scaling properties of entanglement entropy. I will then outline the computation of the sub-leading universal terms in the entanglement entropy for spherical entangling hyper-surfaces in these theories, and discuss the results.
      Speaker: Valentina Giangreco Puletti (University of Iceland)
    • 09:30 10:30
      Holographic Abrikosov lattice 1h 122:026

      122:026

      Nordita, Stockholm

      Speaker: Christiana Pantelidou (Durham University)
      Slides
    • 11:00 11:30
      Instabilities of 2d quantum critical metals in the Nf->0 limit 30m 122:026

      122:026

      Nordita, Stockholm

      We study a Fermi surface coupled to fluctuations of a critical order parameter in 1+2 dimensions. The limit of vanishing fermion flavor number gives a controlled way of studying this strongly coupled theory. In this talk I show how to calculate charge, spin and pairing susceptibilities in this limit and find that the critical fluctuations induce charge/spin density wave order or pairing for come ranges of parameters. We show that adding some of the Nf corrections does not change the range of parameters where these instabilities show up.
      Speaker: Petter Saterskog (Nordita)
      Slides
    • 11:30 12:00
      Holographic tensor models 30m 122:026

      122:026

      Nordita, Stockholm

      Speaker: Nicolas Delporte (LPT Orsay)
      Slides
    • 09:30 10:30
      Transport and Black Hole Horizons 1h 122:026

      122:026

      Nordita, Stockholm

      Speaker: Aristomenis Donos (Durham University)
      Slides
    • 11:00 11:30
      Holographic Plasmons 30m 122:026

      122:026

      Nordita, Stockholm

      Plasmons are ubiquitous in all conducting compounds. We show how to model plasmons holographically, relevant for systems without quasiparticles, e.g. the ‘strange metal’ phase of high temperature superconductors. By introducing holographic electromagnetism we derive a novel set of of boundary conditions which the plasmon modes, and in fact all physical modes, must satisfy. We present the results for both bulk and 2DEG plasmons, and highlight that holographic bulk plasmons exhibit an exotic dispersion in a part of the parameter space not accessible by other methods.
      Speaker: Ulf Gran (Chalmers)
      Slides
    • 11:30 12:00
      Need for sound speed and holography 30m 122:026

      122:026

      Nordita, Stockholm

      Several works in holography has lent support on the conjecture that there could be a universal speed limit for the sound set by the conformal value. Further support comes from kinetic theory and QCD. Yet, there are many instances violating this bound. I furthermore present several holographic models that break the speed barrier and discuss their common denominator.
      Speaker: Niko Jokela (University of Helsinki)
      Slides