**Matteo Baggioli**, Universitat Autonoma de Barcelona

*Jogging Through Holographic Massive Gravity*

We present some recent developments in the framework of holographic (Lorentz violating) massive gravity.

We rigorously define the most generic isotropic setup in 3+1 dimensions and we study in detail its phenomenology.

We describe the electric and the viscoelastic responses of the system and we comment on the fate of the KSS viscosity bound in absence of translational symmetry. We conclude with some discussion hints and comments for the future.

**Michael Blake**, Massachusetts Institute of Technology

*Universal Diffusion and the Butterfly Effect*

In 2014 Hartnoll proposed that the diffusion constants of incoherent metals should be bounded as $ D \geq \hbar v^2/ (k_B T)$, where v is a characteristic velocity. In this talk I will describe a large class of holographic theories that saturate such a bound, with $v$ being the velocity of the butterfly effect. Our results suggest a novel connection between transport at strong coupling and the field of quantum chaos.

**Sera Cremonini,** Lehigh University

*Scaling geometries and DC conductivities*

Non-relativistic geometries that violate hyperscaling have been used as holographic laboratories for probing strongly coupled phases with anomalous scalings. In this talk I will discuss holographic computations of DC conductivities in gravitational systems that exhibit such scalings, and allow for momentum dissipation. I will also comment on the cases in which one obtains a linear temperature dependence for the resistivity.

**Luca Delacretaz**, Stanford University

Hydrodynamic theory of fluctuating stripes

I will present a hydrodynamic description of matter in a charge density wave (or "smectic") phase. As in superfluids, the spontaneous breaking of a continuous symmetry -- here translations in one direction -- adds a Goldstone phase to the usual long lived hydrodynamic variables. This phase propagates as a highly anisotropic "second sound" mode at low energies, affecting properties such as transport. Phase fluctuations, due to proliferating dislocations, give a finite life-time to certain collective modes, which can be experimentally probed e.g. by measuring ultrasound attenuation. Using the memory matrix, the hydrodynamic approach predicts sound attenuation to be proportional to the shear viscosity of the normal (non-smectic) state.

**Angelo Esposito**, Columbia University

*First sound of zero temperature holographic superfluids*

Within the context of AdS/CFT, the gravity dual of an s-wave superfluid is given by scalar QED on an asymptotically AdS spacetime. While this conclusion is vastly based on numerical arguments, I will provide an analytical proof that this is indeed the case. In particular, I will present a technique which allows to explicitely compute the low-energy effective action for the boundary theory starting from the bulk system. This will be done for an arbitrary number of dimensions and an arbitrary potential. I will recover the known dispersion relation for conformal first sound.

**Blaise Gouteraux**, Stanford University & APC, CNRS Paris

*Hydrodynamic theory of quantum fluctuating superconductivity*

A hydrodynamic theory of transport in quantum mechanically phase-disordered superconductors is possible when supercurrent relaxation can be treated as a slow process. We obtain general results for the frequency-dependent conductivity of such a regime. With time-reversal invariance, the conductivity is characterized by a Drude-like peak, with width given by the supercurrent relaxation rate. Using the memory matrix formalism, we obtain a formula for this width (and hence also the dc resistivity) when the supercurrent is relaxed by short range Coulomb interactions. This leads to a new -- effective field theoretic and fully quantum -- derivation of a classic result on flux flow resistance. With strong breaking of time-reversal invariance, the optical conductivity exhibits what we call a `hydrodynamic supercyclotron' resonance. We obtain the frequency and decay rate of this resonance for the case of supercurrent relaxation due to an emergent Chern-Simons gauge field. The supercurrent decay rate in this `topologically ordered superfluid vortex liquid' is determined by the conductivities of the normal component of the liquid. Our work gives a controlled framework for low temperature metallic phases arising from phase-disordered superconductivity.

**Diego Hofman**, University of Amsterdam

*Generalized Global Symmetries and Magnetohydrodynamics*

I will discuss a global symmetry approach to constructing the most general effective field theory of magnetohydrodynamics.

**Leonid Levitov**, Massachusetts Institute of Technology

*Viscous Electron Fluids: Higher-Than-Ballistic Conduction Negative Nonlocal Resistance and Vortices*

**Hong Liu**, Massachusetts Institute of Technology

*Effective field theory of dissipative fluids*

**Andrew Lucas**, Stanford University

*Hydrodynamic theory of transport in Dirac and Weyl semimetals*

I will discuss recent progress in understanding the consequences of hydrodynamic electron flow on measurable transport properties of metals, focusing on metals where the electrons behave as a charge neutral relativistic plasma. In graphene, I will connect our theoretical models with experimental data and show how we can explain features of transport in graphene that are inconsistent with quasiparticle transport. I will then discuss the extension of these results to Weyl semimetals, which are modeled by a system of multiple chiral fluids. Negative magnetoresistance can occur in both electric and thermal transport; the latter is a consequence of a distinct axial-gravitational anomaly. Future transport experiments on Weyl semimetals can discover this exotic type of anomaly in the lab.

**Joseph Maciejko**, University of Alberta

*Superconducting quantum criticality of Dirac fermions*

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 conjecture based on a three-loop analysis. Assuming the conjecture is true, I will present exact results for certain critical properties including the optical conductivity, shear viscosity, and entanglement entropy at zero temperature, as well as the finite-temperature optical conductivity.

J**ohn McGreevy**, University of California, San Diego

*Hierarchical growth of entangled states*

This talk, based on work with Brian Swingle, will describe the s-sourcery program.

Its goal is to extend the lessons of the renormalization group to quantum many body states.

**Jeffrey Murugan**, Institute for Advanced Study

*Particle-Vortex duality and Topological Quantum Matter*

**David Poland**, Yale University

*Bootstrapping 3D CFTs*

I will review recent results from applying the conformal bootstrap to 3D CFTs, including precise determinations of critical exponents and in the 3D Ising and O(N) vector models, new constraints on 3D Gross-Neveu models, and general bounds on correlation function coefficients of currents and stress tensors.

**Marco Polini**, Instituto Italiano de Technolgia

*Hydrodynamic electron transport in a graphene field effect transistor*

Graphene sheets encapsulated between crystals of hexagonal boron nitride host a unique two-dimensional (2D) electron system, whereby electrons suffer minimal scattering against acoustic phonons and practically no scattering against long-range disorder (unless gated very close to the charge neutrality point) [1-4]. Above liquid nitrogen temperatures, these electron liquids are expected to display local equilibrium enabled by strong electron-electron interactions [5,6] and viscosity-dominated hydrodynamic transport.

In this talk I will report on results of combined theoretical and experimental work [7,8] showing unambiguous evidence for this long-sought transport regime. In particular, I will discuss how high-quality doped graphene sheets above liquid nitrogen temperatures exhibit negative non-local resistance near current injection points and whirlpools in the spatial current pattern. Measurements of these non-local electrical signals enable to extract the value of the kinematic viscosity of the two-dimensional massless Dirac fermion liquid in graphene, which is found to compare well with many-body theoretical predictions [6]. If time allows, I will also discuss the subtle connection between negative non-local resistances and current whirlpools [9].

References

[1] A.S. Mayorov et al., Nano Lett. 11, 2396 (2011).

[2] L. Wang et al., Science 342, 614 (2013).

[3] T. Taychatanapat et al., Nature Phys. 9, 225 (2013).

[4] A. Woessner et al., Nature Mater. 14, 421 (2015).

[5] M. Polini and G. Vignale, The quasiparticle lifetime in a doped graphene sheet. In No-nonsense physicist: an overview of Gabriele Giuliani's work and life (eds. M. Polini, G. Vignale, V. Pellegrini, and J.K. Jain) (Edizioni della Normale, Pisa, 2016).

[6] A. Principi, G. Vignale, M. Carrega, and M. Polini, Phys. Rev. B 93, 125410 (2016).

[7] I. Torre, A. Tomadin, A.K. Geim, and M. Polini, Phys. Rev. B 92, 165433 (2015).

[8] D. Bandurin, I. Torre, R.K. Kumar, M. Ben Shalom, A. Tomadin, A. Principi, G.H. Auton, E. Khestanova, K.S. NovoseIov, I.V. Grigorieva, L.A. Ponomarenko, A.K. Geim, and M. Polini, Science 351, 1055 (2016).

[9] F.M.D. Pellegrino, I. Torre, A.K. Geim, and M. Polini, arXiv:1607.03726 (2016).

**Subir Sachdev**, Harvard University & Perimeter Institute

*Theories of non-Fermi liquids*

I will review and compare numerous models for metallic states without

quasiparticle excitations. The solvable SYK model provides a useful starting point,

and also has remarkable holographic connections to the quantum gravity

of black holes in AdS2. Quantum critical states of two-dimensional metals

are obtained by coupling the fermions to fluctuating bosonic order parameters

or gauge fields: I will discuss their physical properties and possible connections

to experiments.

**Kai Sun,** University of Michigan

*Universal features of Lifshitz Green’s functions--- from holography and field theory*

In this talk, we examine the behavior of the retarded Green’s function in theories with Lifshitz scaling symmetry, both through dual gravitational models and a direct field theory approach. In contrast with the case of a relativistic CFT, where the Green’s function is fixed (up to normalization) by symmetry, the generic Lifshitz Green’s function can a priori depend on an arbitrary function Nevertheless, we demonstrate that the imaginary part of the retarded Green’s function (i.e. the spectral function) of scalar operators is exponentially suppressed in a window of frequencies near zero. This behavior is universal in all Lifshitz theories without additional constraining symmetries. On the gravity side, this result is robust against higher derivative corrections, while on the field theory side we present two z>1 examples where the exponential suppression arises from summing the perturbative expansion to infinite order, as a consequence of the energy-momentum conservation.

**Martin Zwierlein**, Massachusetts Institute of Technology

*Solitons and Spin-Charge Correlations in Strongly Interacting Fermi Gases*

Ultracold atomic Fermi gases near Feshbach resonances or in optical lattices realize paradigmatic, strongly interacting forms of fermionic matter. Topological excitations and spin-charge correlations can be directly imaged in real time. In resonant fermionic superfluids, we observe the cascade of solitonic excitations following a pi phase imprint. A planar soliton decays, via the snake instability, into vortex rings and long-lived solitonic vortices.

For fermions in optical lattices, realizing the Fermi-Hubbard model, we detect charge and antiferromagnetic spin correlations with single-site resolution. At low fillings, the Pauli and correlation hole is directly revealed. In the Mott insulating state, we observe strong doublon-hole correlations, which should play an important role for transport.