HoloMatter
Program
Monday 


Schedule  Speaker  Title  Slides  
13:00  15:00  Lunch & Registration  
15:00  16:00  Kamran Behnia  Hydrodynamics of phonons and electrons in threedimensional solids 


16:00  16:30  Coffee Break  
16:30  17:30  Andrew Lucas *  Viscous fluids of electrons 
Tuesday 


Schedule  Speaker  Title  Slides  
10:30  11:30  Koenraad Schalm  Detecting chaos in hydrodynamics 


11:30  12:00  Coffee Break  
12:00  13:00  Philip Phillips  Superconductivity and Mottness: Exact Results 


13:00  15:00  Lunch  
15:00  16:00  Kostya Trachenko  New understanding of the liquid state of matter, viscosity and its lower bounds 


16:00  16:30  Coffee Break  
16:30  17:30  Miguel Angel Ramos  Universal anomalous properties of glasses at low temperatures: are they really universal? 

Wednesday 


Schedule  Speaker  Title  Slides  
10:30  11:30  Yui Ishii * 
Ba1xSrxAl2O4: a new structural quantum material? 


11:30  12:00  Coffee Break  
12:00  13:00  Richard Davison  Relations between transport and chaos in holographic theories 


13:00  15:00  Lunch  
15:00  16:00  Natascia Pinzani Fokeeva  SchwingerKeldysh effective field theories  
16:00  16:30  Coffee Break  
16:30  17:30  Jan Zaanen  Holography in the lab: are the killer aps around the corner? 
Thursday 


Schedule  Speaker  Title  Slides  
10:30 11:30  Martin Ammon  Anomalous hydrodynamics and strong external magnetic fields 


11:30  12:00  Coffee Break  
12:00  13:00  Blaise Gouteraux *  Overview and recent developments in the effective field theory description of superfluids 


13:00  15:00  Lunch  
15:00  16:00  Alberto Nicolis *  Effective field theory methods for phases of matter 


16:00  16:30  Coffee Break  
16:30  17:30  Luca Delacretaz *  Hydrodynamic Fluctuations 

Friday 


Schedule  Speaker  Title  Slides  
10:00  11:00  Saso Grozdanov  Generalised global symmetries and applications 


11:00  11:30  Coffee Break  
11:30  12:30  Carlos Hoyos  Geometry, duality and odd transport in flatland 


12:45  13:45  Rene Meyer  Strongly Correlated Dirac Materials, Electron Hydrodynamics & AdS/CFT 


14:00  END OF THE WORKSHOP 
* : online talks

TALKS:
Ammon Martin (University of Jena)
Title: Anomalous hydrodynamics and strong external magnetic fields
Abstract: TBA
Behnia Kamran (ESPCI Paris)
Title: Hydrodynamics of phonons and electrons in threedimensional solids
Abstract: TBA
Davison Richard (HeriotWatt University)
Title: Relations between transport and chaos in holographic theories
Abstract: I will describe recent work illustrating general relations between the transport properties and chaotic properties of quantum field theories with holographic duals. I will firstly show how a simple analysis of nearhorizon dynamics yields exact constraints on the spectrum of collective excitations. I will then describe how this can be exploited to identify a universal feature in the spectrum, and its implications for the collective transport properties of strongly interacting field theories with gravity duals.
Delacretaz Luca (University of Chicago)
Title: Hydrodynamic Fluctuations
Abstract: TBA
Fokeeva Pinzani Natascia (University of Leuven)
Title: SchwingerKeldysh effective field theories
Abstract: In this talk, I will review a recent reformulation of fluid dynamics as an effective field theory based on an underlying SchwingerKeldysh path integral.
Gouteraux Blaise (Ecole Polytechnique Paris)
Title: Overview and recent developments in the effective field theory description of superfluids
Abstract: Superfluids are one of the hallmarks of 20th century physics. Superfluid phases of matter are typically described at low energies and nonzero temperatures by an effective theory, the LandauTisza twofluid model, which assumes the coexistence of a superfluid, dissipationless flow and a normal, dissipative flow. At zero temperature, the flow becomes entirely superfluid. In this case, a (relativistic) quantum effective action for the Goldstone has been written, and further works have studied finite temperature corrections. Holographic superfluids have also been shown to be described by the LandauTisza model, for the most part. I will then move on to explain how holographic superfluids with a Lifshitzinvariant quantum critical IR geometry lead to a nonvanishing normal component at zero temperature, suggesting that these are not described by the universal relativistic quantum effective action mentioned above. I will also explain how this could be relevant for recent measurements of the superfluid density and ac conductivity at low temperatures in overdoped high Tc superconductors.
Grozdanov Saso (MIT & University of Ljubljana)
Title: Generalised global symmetries and applications
Abstract: Generalised global symmetries or higherform symmetries are a novel concept in quantum field theories that enables the formulation of a conservation of higherdimensional objects. While standard (zeroform) symmetries act on local operators, a oneform symmetry can act on the onedimensional Wilson line. These symmetries can be discrete, continuous, broken, anomalous, etc. In Nature, the simplest realisation of a continuous oneform symmetry stems from the conservation of the number of magnetic flux lines due to the absence of magnetic monopoles. The fact that such symmetries must play a crucial role in the formulation of effective field theories has led to the first, and so far best understood application: the theory of magnetohydrodynamics, which is the theory of longrange excitations in magnetised plasmas. In this review talk, I will first discuss the mathematical details of generalised global symmetries. I will then focus on the new theory of magnetohydrodynamics and summarise how it interpolates between previously known theories (standard nonrelativistic magnetohydrodynamics, forcefree electrodynamics, dynamics of fermions in the lowest Landau level) and enables to find their systematic corrections. The presentation of other applications of generalised global symmetries will include generic string liquids, superfluids and the theory of elasticity. Finally, I will show how generalised global symmetries can be implemented in AdS/CFT and discuss how the construction of the holographic dual to a plasma with dynamical magnetic fields gives rise to a strongly coupled field theory with dynamical photons and extends magnetohydrodynamics into the ultraviolet regime.
Hoyos Carlos (University of Oviedo)
Title: Geometry, duality and odd transport in flatland
Abstract: Effective theories are very useful to extract transport properties at
long wavelengths, which can be done by studying the response to
external sources and geometric deformations. In two dimensions one can
also take advantage of particlevortex duality which allows a similar
description for Quantum Hall states and superfluids/superconductors
using statistical gauge fields. I will discuss the effective theory
description of twodimensional states with broken parity and
timereversal invariance and the relation between odd transport and
symmetry and topological properties of the state.
Ishii Yui (Osaka Prefecture University)
Title: Ba1xSrxAl2O4: a new structural quantum material?
Abstract: TBA
Lucas Andrew (University of Colorado Boulder)
Title: Viscous fluids of electrons
Abstract: It was conjectured over 50 years ago that electrons in a high quality conductor could flow collectively as a viscous fluid, just like air or water. While impurities and umklapp scattering forbid this behavior in conventional metals, it has now become possible to study electrons that flow like classical fluids in high quality devices. I will overview the nature of hydrodynamic transport in electrons together with some recent experiments that allow us to directly probe this behavior.
Meyer Rene (University of Wuerzburg)
Title: Strongly Correlated Dirac Materials, Electron Hydrodynamics & AdS/CFT
Abstract: TBA
Nicolis Alberto (University of Columbia)
Title: Effective field theory methods for phases of matter
Abstract: TBA
Phillips Philip (ICMT  University of Illinois)
Title: Superconductivity and Mottness: Exact Results
Abstract: Because the cuprate superconductors are doped Mott insulators, it would be advantageous to solve even a toy model that exhibits both Mottness and superconductivity. We consider the HatsugaiKohmoto model, an exactly solvable system that is a prototypical Mott insulator above a critical interaction strength at half filling. Upon doping or reducing the interaction strength, our exact calculations show that the system becomes a nonFermi liquid metal with a superconducting instability. In the presence of a weak pairing interaction, the instability produces a thermal transition to a superconducting phase, which is distinct from the BCS state, as evidenced by a gaptotransition temperature ratio exceeding the universal BCS limit. The elementary excitations of this superconductor are not Bogoliubov quasiparticles but rather superpositions of doublons and holons, composite excitations signaling that the superconducting ground state of the doped Mott insulator inherits the nonFermi liquid character of the normal state.
Ramos Miguel Angel
Title: Universal anomalous properties of glasses at low temperatures: Are they really universal?
Abstract: Glasses (amorphous solids) are known to universally exhibit anomalous properties at low temperatures very different from their crystalline counterparts. Specifically, below 12 K the specific heat C_{p} (T) of glasses shows a linear temperature dependence and the thermal conductivity k(T) a quadratic dependence on temperature in contrast with the expected cubic behavior of crystals following Debye’s theory, that has been ascribed to the ubiquitous existence of tunneling twolevel systems (TLS). Moreover, at a few K, k (T) of glasses exhibits a plateau and the specific heat a broad peak in C_{p}/T^{ }^{3}, which has been associated to an excess in the Debyereduced vibrational density of states g(w)/w^{ }^{2} (the “boson peak”). In the last decades, some disordered crystals such as orientational glasses (a.k.a. “glassy crystals”), obtained by quenching a plastic crystal phase, have been found to present the very same glassy features. Nevertheless, recent works are casting doubts about this universality of “glassy behavior”. On the one hand, some genuine amorphous solids have been found to lack TLS at low temperatures, whereas some truly crystalline solids, devoid of orientational disorder, seem to exhibit those glassy features.
I will discuss this fascinating topic by presenting our recent experiments on different molecular solids, ranging from crystals with a minimal amount of disorder exhibiting glassy behavior to the special case of “ultrastable glasses”, aiming to shed light on this issue.
Schalm Koenraad (InstituutLorentz and University of Leiden)
Title: Detecting chaos in hydrodynamics
Abstract: Hydrodynamics assumes local equilibration and equilibration assumes ergodic mixing driven by chaos  at least in semiclassical systems. For a generic such system the timescales of macroscopic thermalization and onset of microscopic chaos are very different. Nevertheless, it is a pillar of Boltzmann transport that longtime equilibration can be computed from microscopic dynamics. We show how in these systems the two timescales are in fact related. Moreover, we show that a similar connection between both scales surprisingly also exists in extremely strongly coupled systems through a phenomenon christened poleskipping in hydrodynamic response.
Trachenko Kostya (Queen Mary University London)
Title: New understanding of the liquid state of matter, viscosity and its lower bounds
Abstract: Understanding most basic thermodynamic properties of the liquid state such as energy and heat capacity turned out to be a longstanding problem in physics [1]. Landau&Lifshitz textbook states that no general formulas can be derived for liquid thermodynamic functions because the interactions are both strong and systemspecific. Phrased differently, liquids have no small parameter. Recent experimental and theoretical results open a new way to understand liquid thermodynamics on the basis of collective modes (phonons) as is done in the solid state theory. There are important differences between phonons in solids and liquids, and we have recently started to understand and quantify this difference. I will review collective modes in liquids including highfrequency solidlike transverse modes and will discuss how a gap in the reciprocal space emerges and develops in their spectrum [2]. This reduces the number of phonons with temperature, consistent with the experimental decrease of constantvolume specific heat with temperature [1]. I will discuss the implication of the above theory for fundamental understanding of liquids. I will also mention how this picture can be extended above the critical point where the recently proposed Frenkel line on the phase diagram separates liquidlike and gaslike states of supercritical dynamics [1,35].
I will subsequently describe our recent work where we calculated the minimal quantum viscosity in terms of fundamental physical constants and compared this minimum to the bound of Kovtun, Son&Strarinets [6]. Finally, I will note the similarity of the kinematic viscosity of liquids and the quarkgluon plasma.
1. K. Trachenko and V. V. Brazhkin, Collective modes and thermodynamics of the liquid state, Reports on Progress in Physics 79, 016502 (2016).
2. C. Yang, M. T. Dove, V. V. Brazhkin and K. Trachenko, Physical Review Letters 118, 215502 (2017).
3. V. V. Brazhkin and K. Trachenko, Physics Today 65(11), 68 (2012).
4. V. V. Brazhkin et al, Physical Review Letters 111, 145901 (2013).
5. D. Bolmatov, V. V. Brazhkin and K. Trachenko, Nature Comm. 4:2331 (2013).
6. K. Trachenko and V Brazhkin, Minimal quantum viscosity from fundamental physical constants,arXiv:1912.06711
Zaanen Jan (InstituutLorentz and University of Leiden)
Title: Holography in the lab: are the killer aps around the corner?
Abstract:

POSTERS:
Matthaiakakis Ioannis (University of Würzburg)
Title: Proposal for measuring the Hall viscosity in twodimensional Fermi liquids
Abstract: The absence of parity and timereversal symmetry in twodimensional Fermi liquids gives rise to nondissipative transport features characterized by the Hall viscosity. For nonvanishing magnetic fields, the Hall viscous force directly competes with the Lorentz force, since both mechanisms contribute to the Hall voltage. We present how one can distinguish the two contributions in a channel geometry admitting a Poiseuille flow profile. In particular, we derive the depence of the Hallviscous response in all of the external parameters, such as the channel width, the channel's slip length and the liquid's equilibrium density.
Title: Renormgroup flow in anisotropic QGP with nonzero chemical potential
Abstract: In our previous work (Aref’eva, KR, JHEP 1805 (2018) 206 [arXiv:1802.05652 [hepth]]) we obtained the RGflow equations, describing isotropic QGP with nonzero chemical potential. In this work we consider the anisotropic QGP and particular cases in more details.
Russell Matthew (Southampton University)
Title: Translational symmetry breaking via massive gravity in holographic zero sound.
Abstract: The gauge/gravity duality is a useful resource for studying the properties of strongly coupled systems in condensed matter physics and QCD, an example of which are strange metals: strongly interacting electrons that exhibits nonFermi Liquid behaviour. In a weakly coupled neutral Fermi Liquid a sound mode is found at low temperature: zero sound. A somewhat similar, but different, mode is found at low temperatures holographically (strongly coupled!): holographic zero sound (HZS). This poster would present how sound modes are calculated in the gauge/gravity duality, the importance of translational symmetry breaking (TSB) in modelling real systems, how TSB can be included in the duality via massive gravity and the effects of TSB on the spectrum of quasinormal modes of probe brane HZS.
Rigatos Konstantinos (University of Southampton)
Title: Fermions from probe branes and doubletrace deformations
Abstract: Motivated by Beyond the Standard Model Physics we proposed a holographic mechanism that generates light baryonic states in a strongly coupled gauge theory. We study the spin1/2 open string fluctuations in probebrane systems, and the fermionic mesons that arise can be seen as realisations of composite fermions. We then add higher dimension operators using Witten’s double trace prescription
Angel Lopez Corps (UCM Madrid)
Title: Does the ergodic phase of disordered quantum spin chains survive in the thermodynamic limit?
Abstract: Within the Thouless energy scale, manybody Hamiltonians behave like random matrices. We study the Thouless energy of the Heisenberg quantum spin chain as a function of the strength of a disordered magnetic field. This model has become the standard model for the study of manybody localization and the transition to an ergodic phase for weak disorder. The Thouless energy extracted from long range spectral statistics and from the power spectrum of the fluctuations of the full momentum distribution coincide. This scale behaves nonmonotonically and is peaked at an intermediate value of the disorder. An analysis of the scaling behavior of the Thouless energy and its comparison with the number of populated eigenstates after a quench hints towards the absence of thermalization in the thermodynamic limit. The ergodic phase may, then, not survive as such in the infinite system.
Watse Sybesma (University of Iceland)
Title: Instabilities in nonLorentzian fluids
Abstract: I discuss linear instabilities of hydrodynamics with corrections up to first order in derivatives. It has long been known that relativistic (Lorentzian) first order hydrodynamics, with positive local entropy production, exhibits unphysical instabilities. I extend this analysis to fluids with Galilean and Carrollian boost symmetries. I find that the instabilities occur in all cases, except for the fluids Galilean boost with the choice of macroscopic variables called Eckart frame. I also present a complete linearised analysis of the full spectrum of first order Carrollian hydrodynamics. Furthermore, I show that even in a fluid without boost symmetry present, instabilities can occur. These results provide evidence that the unphysical instability is a symptom of first order hydrodynamics, rather than a special features of the Lorentzian fluid.
Ram Chandra Sapkota (Tribhuvan University)
Title: Study IV Characteristics Of Resonant Tunneling Diodes using Nonequilibrium Green's function (NEGF)
Abstract: In this work, we perform a comprehensive analysis of modeling of resonant tunneling diode (RTD) based on quantum model. RTDs operate on the principle of quantum mechanical tunneling of electrons through a potential barrier into quantized well states resulting in resonances in the transmission characteristics. The electron density and the charge selfconsistent electrostatic potential profile in the device is analyzed by employing ThomasFermi model and Hartree model. The Nonequilibrium Green's function (NEGF) formalism using effective mass approach is developed to study GaAs/AlGaAs RTD to obtain the I–V characteristics. The Performance characteristics of the device like negative differential resistance (NDR) and PeaktoValley Current Ratio (PVCR) has been discussed. The Variation in I–V characteristics with variation of wellwidth and barrierwidth has been plotted and their causes have been analyzed.
Gian Andrea Inkof (Karlsruher Institut für Technologie)
Title: JTgravity superconductor
Abstract: The tendency of nonFermi liquid states towards superconductivity through pairing of fermionic excitations is complicated by the disappearance of quasiparticles at strong coupling. Recently solvable SYKlike models of randomly interacting electrons and phonons have been shown to match many of the properties of nonFermi liquid superconductors. The system has an emergent reparametrization invariance and is argued to be described by a Schwarzian action, typical of SYKlike models. At these low energies the system is strongly coupled and is conjectured to have a holographic dual. We perform a dimensional reduction of the holographic superconductor and obtain a dilatonJTMaxwellgravity theory coupled to an order parameter in 2 dimensions, through which we aim to describe the strongly coupled superconducting phase of the disordered electronphonon gas.
Sebastian Grieninger (University of Jena)
Title: On the hydrodynamic description of holographic viscoelastic models
Abstract:
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