MPS Conference on Ultra Quantum Matter II

  • Organized by
  • Leon Balents, Ph.D.UC Santa Barbara
  • Victor Galitski, Ph.D.Joint Quantum Institute
    University of Maryland, College Park
  • Victor Gurarie, Ph.D.University of Colorado Boulder
  • Michael Hermele, Ph.D.University of Colorado Boulder
  • Ashvin Vishwanath, Ph.D.Harvard University
Date & Time


Gerald D. Fischbach Auditorium
160 5th Ave
New York, NY 10010 United States

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Invitation Only

Participation is by invitation only. All participants must register.

In the century since its discovery, quantum mechanics has enthralled and astounded scientists and non-scientists alike with its dramatically non-intuitive nature. While quantum effects are all-important at atomic lengths, they are usually less evident at the human scale. However, a series of revolutionary developments in theoretical physics has revealed that even macroscopic systems consisting of many atoms or electrons (i.e. matter) can behave in an essentially quantum way. Such ultra-quantum matter (UQM) is characterized by non-local quantum entanglement that is robust under perturbations.

Progress is being made in classifying stable phases of UQM. Two dimensional gapped UQM states have been characterized and generalizations of these states in three dimensions are being explored. Exciting connections between gapless UQM states and non-Fermi liquid metals have been established. UQM states may even occur far from equilibrium in driven or “hot” systems with potentially dramatic consequences.

The time is ripe to begin to bridge the gap from theoretical characterization and classification to realization of new forms of UQM in the lab, and to define and construct experimental probes that will access the quantum non-locality underlying UQM.

Topics to be discussed at the second MPS Conference on Ultra-Quantum Matter include:

  1. Connections between properties of gapped topological phases and their gapless surface states, quantum critical points and dualities
  2. Applications to experiments in quantum Hall systems and quantum magnets
  3. Anomalous transport, bad metals and soluble models of non-Fermi liquids from coupled SYK models and insight from gravity duals
  4. Entanglement structure of UQM and measurement of entanglement in many body quantum systems


  • Agendaplus--large


    9:30 AMLeon Balents | Ultra-Quantum Matter, from Theory to Experiment
    10:30 AMBREAK
    11:00 AMMichael Levin | Constraints on Order and Disorder Parameters in Quantum Spin Chains and Applications
    12:00 PMLUNCH
    1:30 PMAndreas Karch | Dualities in 2+1 Dimensions and Beyond
    2:30 PMBREAK
    3:00 PMJohn McGreevy | Hierarchical Growth of Entangled States, or s-sourcery
    4:00 PMBREAK
    4:30 PMVarious | Short Talks
    Gang Chen | Signature of Fractionalization in Spin Liquids
    Debanjan Chowdhury | Unusual Transport in Strongly Correlated Metallic Systems
    Lukasz Fidkowski | Disentangling Fermionic Symmetry Protected Phases
    Tim Hsieh | Efficient Preparation of Nontrivial Quantum States
    Vedika Khemani | TBA


    9:30 AMNathan Seiberg | Recent Advances in 2+1d QFT
    10:30 AMBREAK
    11:00 AMSubir Sachdev | Gauge Theories of Ultra-Quantum Metals
    12:00 PMLUNCH
    1:30 PMT. Senthil | Quantum Criticality, Topology and Dualities
    2:30 PMBREAK
    3:00 PMPeter Zoller | Quantum Simulation with Cold Atoms and Ions
    4:00 PMBREAK
    4:30 PMMarcus Greiner | Observing String Pattern in a Doped Hubbard Model Quantum Simulation


    9:30 AMJuan Maldacena | Traversable Wormholes
    10:30 AMBREAK
    11:00 AMPablo Jarillo-Herrero | Magic Angle Graphene: A New Platform for Strongly Correlated Physics
    12:00 PMLUNCH
    1:00 PMAshvin Vishwanath | Modeling Correlated Phenomena in Twisted Bilayer Graphene
  • Abstractsplus--large

    Leon Balents
    UC Santa Barbara

    Ultra-Quantum Matter, from Theory to Experiment

    Ultra-quantum matter brings together many communities of theoretical research, from mathematical physicists to condensed matter and atomic theorists to string theorists. This talk will focus on how it connects to experimental studies and discuss promising examples of the latter and the questions they raise.


    Pablo Jarillo-Herrero

    Magic Angle Graphene: A New Platform for Strongly Correlated Physics

    The understanding of strongly correlated quantum matter has challenged physicists for decades. Such difficulties have stimulated new research paradigms, such as ultra-cold atom lattices for simulating quantum materials. In this talk, I will present a new platform to investigate strongly correlated physics, based on graphene moiré superlattices. In particular, I will show that when two graphene sheets are twisted by an angle close to the theoretically predicted ‘magic angle,’ the resulting flat band structure near the Dirac point gives rise to a strongly-correlated electronic system. These flat bands exhibit half-filling insulating phases at zero magnetic field, which we show to be a correlated insulator arising from electrons localized in the moiré superlattice. Moreover, upon doping, we find electrically tunable superconductivity in this system, with many characteristics similar to high-temperature cuprates superconductivity. These unique properties of magic-angle twisted bilayer graphene open up a new playground for exotic many-body quantum phases in a 2-D platform made of pure carbon and without magnetic field. The easy accessibility of the flat bands, the electrical tunability and the bandwidth tunability though twist angle may pave the way toward more exotic correlated systems, such as quantum spin liquids or correlated topological insulators.


    Andreas Karch
    University of Washington

    Dualities in 2+1 Dimensions and Beyond

    After a brief review of the flurry of recent developments regarding dualities in 2+1 dimensions, I’ll describe our progress toward using these novel dualities to gain insights into 3+1 and 1+1 dimensional physics. In particular, I’ll show that the strong-weak coupling duality of maximally supersymmetric gauge theories in 3+1 dimensions, as well as bosonization in 1+1 dimensions, can be derived from well-known 2+1 dimensional dualities.


    Michael Levin
    University of Chicago

    Constraints on Order and Disorder Parameters in Quantum Spin Chains and Applications

    I will discuss a theorem that shows that a gapped ground state of an Ising symmetric quantum spin chain must have either a nonzero order parameter or a nonzero disorder parameter. I will also discuss an application of this theorem to understanding the stability/instability of gapless edge modes of a large class of two-dimensional topological phases.


    Juan Maldacena
    Princeton University

    Traversable Wormholes

    We discuss how the coupling of two SYK models by simple operators gives rise to a gapped state that displays many features of the approximate SL(2) conformal symmetry of the theory. The configuration is related to traversable wormholes in gravity. We will further show how the intuition generated by solving this model leads to an interesting solution describing a traversable wormhole in four dimensions.


    John McGreevy
    UC San Diego

    Hierarchical Growth of Entangled States, or s-sourcery

    This talk will describe the s-sourcery program, an attempt to extend the lessons of the renormalization group to quantum many-body states. Outcomes so far include a classification axis for states of matter, a proof of the area law for entanglement entropy of subregions (under mild assumptions) and a new algorithm for constructing efficiently contractible tensor network representations of ground states. I’ll describe recent progress on implementing this algorithm.


    Subir Sachdev
    Harvard University

    Gauge Theories of Ultra-Quantum Metals

    Metals with local antiferromagnetic spin correlations can be conveniently described by transforming to a rotating reference frame in spin space, leading to a theory with an emergent SU(2) gauge field. The Higgs phases of such a theory will be compared with numerical cluster-DMFT studies of the lightly doped square lattice Hubbard model. The Higgs phases can also help understand recent photoemission observations in the electron-doped cuprate NCCO, which detected a reconstruction gap in the electronic dispersion at a doping where there is no antiferromagnetic order. The transitions out of the Higgs phases into confining phases are promising routes to understanding the strange metal behavior seen at optimal and over-doping, after including the effects of disorder. I will discuss models of strange metals built out of SYK islands, including cases with emergent gauge fields.


    Nathan Seiberg
    Institute for Advanced Study

    Recent Advances in 2+1d QFT

    We will review recent developments in the study of quantum field theory in 2+1 dimensions. Newly discovered subtleties in the analysis of the short-distance behavior of these theories have uncovered surprising properties. They help motivate a rich web of conjectures about the long-distance behavior of these systems. These conjectures describe new phases and new-phase transitions between them. Also, in many cases, these transitions have several different dual descriptions. These new developments were motivated by ideas in high-energy physics, string theory and condensed matter physics. And they have potential applications in these fields.


    T. Senthil

    Quantum Criticality, Topology and Dualities

    I will describe recent progress in our understanding of unusual quantum critical points that lie outside the standard Landau paradigm. Crucial recent theoretical input into these quantum critical points has come from the study of gapped topological phases of matter and from the understanding of dualities of quantum field theories. I will highlight these connections and describe several new results on quantum critical points in 3+1 dimensional systems.


    Ashvin Vishwanath
    Harvard University

    Modeling Correlated Phenomena in Twisted Bilayer Graphene

    The recent discovery of superconductivity and Mott insulators in twisted bilayer graphene and related materials points to the importance of correlation effects in this new solid state physics platform. An interesting and potentially crucial ingredient is band topology inherited from the Dirac fermion dispersion of graphene. We will discuss our theoretical efforts to model these systems and study the resulting ground states with interactions. We find that key aspects of the physics differ from previously studied correlated superconductors.


    Peter Zoller
    Center for Quantum Physics, University of Innsbruck, and
    Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, Innsbruck

    Quantum Simulation with Cold Atoms and Ions

    Zoller will discuss recent developments in quantum simulation of quantum many-body systems with atomic platforms from a theory perspective. Systems of interests include atoms in optical lattices, Rydberg atoms in optical tweezer arrays, and trapped ions. Quantum simulation has so far been discussed as analog simulation, where we physically build a system with the desired Hamiltonian; or as digital quantum simulation, where time evolution of a many-body system is represented as a sequence of quantum gates on a quantum computer. Zoller will add to this variational quantum simulation, based on a quantum feedback loop between a classical computer and an analog quantum simulator, which acts as a quantum co-processor. As an example, he will present results from an ongoing theory – experiment collaboration in Innsbruck: here our quantum resource is an analog quantum simulator with trapped ions, representing a transverse Ising model, and we compute on the quantum device the ground and excited state wave functions of the Lattice Schwinger Model as 1D QED. Remarkably, variational quantum simulation allows "self-verification" of quantum results on the quantum machine. As a second topic we will discuss novel measurement protocols for Rényi entropies, and for out-of-time-ordered correlation functions (OTOCs), which can be extracted from on statistical correlations between randomized measurements. Zoller will show a recent experiment with a (single) ion chain demonstrating experimental observation of entanglement entropies in quench dynamics. He will conclude his talk with a brief outlook on possible future directions, including sub-wavelength optical lattices for atomic Hubbard models, and quantum chemistry.

  • Travelplus--large

    Air and Train

    Group A
    The foundation will arrange and pay for all air and train travel to the conference for those in Group A. Please provide your travel specifications by clicking the registration link above. If you are unsure of your group, please refer to your invitation sent via email.
    Group B
    Individuals in Group B will not receive travel or hotel support. Please register at the link above so we can capture your dietary requirements. If you are unsure of your group, please refer to your invitation sent via email.

    Personal Car

    For participants in Group A driving to Manhattan, The Roger Hotel offers valet parking. Please note there are no in-and-out privileges when using the hotel’s garage, therefore it is encouraged that participants walk or take public transportation to the Simons Foundation.
  • Hotelplus--large

    Participants in Group A who require accommodations are hosted by the foundation for a maximum of four nights at The Roger hotel. Any additional nights are at the attendee’s own expense.

    The Roger New York
    131 Madison Avenue
    New York, NY 10016
    (between 30th and 31st Streets)

    To arrange accommodations, please register at the link above.

    For driving directions to The Roger, please click here.

  • Contactsplus--large

    Travel Assistance

    Christophe Vergnol, Protravel International

    Registration, Hotel and General Meeting Assistance

    Meghan Fazzi
    Senior Executive Assistant, Simons Foundation
    (212) 524-6080

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