Events Archive

Condensed Matter Seminar - Engineering topological phases with a superlattice potential
Tue, Nov 29, 2022, 12:00 pm1:30 pm

Abstract: We propose an externally imposed superlattice potential as a platform for manipulating topological phases, which has both advantages and disadvantages compared to a moire superlattice. In the first example, we apply the superlattice potential to the 2D surface of a 3D topological insulator. The superlattice potential creates tunable…

PostPandemic Tool for Quantum Materials and vice-versa
Tue, Nov 15, 2022, 12:30 pm1:30 pm

Raman scattering, invented at the end of the last pandemic, can provide a wealth of information on the fractional, magnetic, lattice and charge excitations at the heart of quantum materials and devices. I will first discuss how Raman provides direct evidence for coupled phonon-electron fluids in topological semimetals, helping to explain their…

Special Condensed Matter Seminar: Thermodynamic sensing of correlated insulators and their excitations in moiré materials
Fri, Sep 30, 2022, 12:30 pm1:30 pm

Abstract: Twisted van der Waals materials provide a new venue to explore flat electronic bands and the interaction-driven states they host. While many such phases have been reported, little is known about their excitations or how they depend on externally applied fields. In this talk, I will present two examples where…

Pseudo-Gauge Field in Dirac/Weyl Materials/ Chaoxing Liu/ Pennsylvania State University
Tue, Nov 9, 2021, 12:30 pm12:30 pm


In solid materials, electrons are usually described by the non-relativistic Schrodinger equation since electron velocity is much slower than the speed of light. However, the relativistic Dirac/Weyl equation can emerge as a low-energy effective theory for electrons in certain materials. These systems are…

CM/AMO Seminar/Spin dynamics of ultracold atoms in optical lattices/Wolfgang Ketterle, MIT
Tue, Oct 26, 2021, 12:30 pm12:30 pm

Ultracold atoms offer a unique platform to perform quantum simulations of quantum materials and many-body systems.  When atoms with spin are arranged in an optical lattice in form of a Mott insulator, they realize paradigmatic Heisenberg spin models, where only neighboring spins interact.  Until very recently, all experimental studies with cold…

Condensed Matter Seminar/Toward Practical Quantum Advantage: Many-body Physics in the NISQ Era - Xiao Mi, Research Scientist, Google
Tue, Oct 5, 2021, 12:30 pm12:30 pm



    Quantum processors of today are already capable of surpassing classical supercomputers on certain specialized tasks [1]. A current milestone for the quantum information science community is the fulfilment of…

Condensed Matter Seminar - TBD
Tue, Sep 28, 2021, 12:30 pm12:30 pm
Condensed Matter Seminar - "Interplay of correlations and topology in the narrow bands of twisted bilayer graphene" Oskar Vafek, Florida State University
Tue, Sep 21, 2021, 12:30 pm12:30 pm

I will present an overview of the current theoretical understanding of the remarkable phenomenology of the twisted bilayer graphene (TBG) near the magic angle.  This includes the early insights obtained using the 2D exponentially localized Wannier basis[1] which revealed a qualitative difference between the effect of the…

Special Condensed Matter Seminar - Yichen Huang, MIT, "Entanglement dynamics from random product states at long times"
Wed, Jun 16, 2021, 2:00 pm2:00 pm

We study the entanglement dynamics of quantum many-body systems at long times.

For upper bounds, we prove the following: (I) For any geometrically local Hamiltonian on a lattice, starting from a random product state the entanglement entropy almost never approaches the Page curve. (II) In a spin-glass model with random all-to-all…

Condensed Matter Zoom Seminar | Srinivas Raghu, Stanford | "Lattice constructions of a web of dualities in 3 spacetime dimensions"
Wed, May 26, 2021, 2:00 pm2:00 pm

Duality transformations have played a major role in our modern understanding of quantum phenomena.  In 3 spacetime dimensions, familiar examples of duality transformations include 1) Goldstone modes of the XY model being dual to a photon, and 2) dualities involving statistical transmutation.  It has become clear recently that both of these…

Condensed Matter Zoom Seminar | Andrea Young, UCSB | "Orbital magnetism in graphene heterostructures"
Wed, May 19, 2021, 2:00 pm2:00 pm

I will describe experiments probing magnetic states based on the spontaneous alignment of electron orbitals. Such orbital ferromagnetism may be a generic phenomena, but has, to date, found its fullest expression in graphene heterostructures in which the two dimensional orbits of electrons in distinct momentum space valleys provide the…

Condensed Matter Zoom Seminar | Siddharth Parameswaran | "Topology and broken symmetry of excitons in two-dimensional materials"
Wed, Apr 28, 2021, 2:00 pm2:00 pm

I will discuss recent  theoretical work on exciton physics in two-dimensional materials. First, I will focus on the neutral particle-hole pair excitations of correlated “orbital Chern insulators” recently detected in twisted bilayer graphene, whose approximately flat conduction and valence bands have equal and opposite non-zero Chern number…

Condensed Matter Zoom Seminar | Ana Maria Rey, U Colorado | "Advances in Quantum Simulation with Planar Ion Crystals"
Wed, Apr 21, 2021, 2:00 pm2:00 pm

 In this seminar I will discuss recent progress on the use of planar crystals with hundreds of ions as a platform for quantum simulation of spin and spin-boson models. The key idea is the use of a pair of lasers to couple two internal levels of the ions, that act as a spin½ degree of freedom, to the…

Condensed Matter Zoom Seminar | Claudio Chamon, Boston U. | "TBA"
Wed, Apr 14, 2021, 2:00 pm2:00 pm


Condensed Matter Zoom Seminar | Charles Kane, U Penn.| "Translation symmetry enriched topological phases"
Wed, Apr 7, 2021, 2:00 pm2:00 pm

The interplay between symmetry and topology allows a rich variety of electronic phases.  For layered systems, symmetry under translation by one layer protects the 3D weak topological insulator, which can be viewed as a stack of 2D topological insulators and the 2D 'weak topological superconductor', which is a stack of 1D topological…

Condensed Matter Zoom Seminar | Eugene Demler, Harvard | "A new perspective on magnetic polarons from cold atoms"
Wed, Mar 31, 2021, 2:00 pm2:00 pm

What can we learn about a many-body system when we measure every constituent particle? Current experiments with ultracold atoms provide snapshots of many-body states with single particle resolution. I will present a recent application of this method to study magnetic polarons in antiferromagnetic Mott insulators. In…

Condensed Matter Zoom Seminar | Anton Kapustin, Caltech | "Higher-dimensional generalizations of the Berry curvature for gapped lattice systems"
Wed, Dec 16, 2020, 3:00 pm3:00 pm

Building on the work of von Neumann and Wigner, M. Berry showed that there are topologically protected level-crossings in the space of quantum systems. These level-crossings can be detected using the curvature of the Berry connection. In this talk I will describe analogs of this for interacting lattice systems in infinite volume. Although the…

Condensed Matter Zoom Seminar | Christian Gross, U of Tuebingen | "Microscopic spin and density cross-correlations in the Hubbard systems"
Wed, Dec 9, 2020, 1:00 pm1:00 pm

Quantum gas microscopes provide experimental access to novel observables, foremost, single particle resolved multi-point correlation functions. These offer a novel microscopic window into the physics of strongly correlated many-body physics. In our setup we developed a method for the simultaneous detection of spin and…

Condensed Matter Zoom Seminar | Titus Neupert,UZH | "Heating and blackhole dynamics in critical Floquet systems"
Wed, Nov 18, 2020, 1:00 pm1:00 pm

While driven interacting quantum matter is generically subject to heating and scrambling, certain classes of systems evade this paradigm. I will discuss such an exceptional class in periodically driven critical (1 + 1)-dimensional systems with a spatially modulated, but disorder-free time evolution operator. Instead of complete scrambling, the…

Condensed Matter Zoom Seminar | Jiaxin Yin | "Tunneling into emergent topological matter"
Wed, Nov 11, 2020, 1:00 pm1:00 pm

The search for topological matter is evolving towards strongly interacting systems including topological magnets and superconductors, where novel effects emerge from the quantum level interplay between geometry, correlation, and topology. Equipped with unprecedented spatial resolution, electronic detection, and…