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.

# Events Archive

## Condensed Matter Seminar

### Condensed Matter Zoom Seminar | Anton Kapustin, Caltech | "Higher-dimensional generalizations of the Berry curvature for gapped lattice systems"

### Condensed Matter Zoom Seminar | Christian Gross, U of Tuebingen | "Microscopic spin and density cross-correlations in the Hubbard systems"

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.

### Condensed Matter Zoom Seminar | Titus Neupert,UZH | "Heating and blackhole dynamics in critical Floquet systems"

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.

### Condensed Matter Zoom Seminar | Jiaxin Yin | "Tunneling into emergent topological matter"

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.

### Condensed Matter Zoom Seminar | Johnpierre Paglione, U of MD | "Exotic superconductivity in nearly ferromagnetic UTe2"

Topological superconductivity has attracted great interest in condensed matter physics because of its potential applications in quantum computing. Spin-triplet superconductors are one promising class that can host the topological excitations of interest, but experimental realizations are few and far between.

### Condensed Matter Zoom Seminar | Pedram Roushan, Google | " Tuning quantum information scrambling in two-dimensional systems"

The promise of quantum computers is that certain computational tasks might be executed exponentially faster on a quantum processor than on a classical processor.

### Condensed Matter Zoom Seminar | Dmitri Efetov, ICFO | "Magic Angle Bilayer Graphene - Superconductors, Orbital Magnets, Correlated States and beyond"

When twisted close to a magic relative orientation angle near 1 degree, bilayer graphene has flat moire superlattice minibands that have emerged as a rich and highly tunable source of strong correlation physics, notably the appearance of superconductivity close to interaction-induced insulating states.

### Virtual Condensed Matter Seminar | Yuan Cao, MIT | "Competing Orders, Nematicity and Novel Josephson Effects in Superconducting Graphene Superlattices"

The emergence of two-dimensional materials have provided physicists with unprecedented way of studying the motion of electrons in a superconductor. Although superconductivity itself has been studied for more than a century, the recent advances of “twistronics” research in graphene superlattices brings fundamentally new physics into the picture...

### Condensed Matter Seminar | Alexandre Blais, Usherbrooke | "To be announced." | Joseph Henry Room

### Condensed Matter Seminar | Adrian Po, MIT | "Symmetry indicators for topological superconductors" | Joseph Henry Room, Jadwin Hall

A useful guiding principle for the search of topological superconductors is to relate the topological invariants with the behavior of the pairing order parameter on the normal-state Fermi surfaces. In this talk, we will discuss how this paradigm can be integrated with the notion of symmetry indicators, which enables an efficient diagnosis of...

### Condensed Matter Seminar | Mikhail I. Eremets, Max Planck | "Progress in high-temperature conventional superconductivity" PCTS Seminar Room 407

We studied the state of matter under extreme conditions and found new phenomena and materials, including polymeric nitrogen, transparent sodium, semimetallic hydrogen, and superconductivy in various substances.

### Condensed Matter Seminar | Helen Bouchiat, U of Paris Sud | "Revealing the second-order topological character of bismuth-based Josephson junction" | Joseph Henry Room

In Second-Order Topological Insulators (SOTI), bulk and surfaces are insulating while the edges or hinges conduct current in a quasi-ideal (ballistic) way, being insensitive to disorder. Crystalline bismuth has been shown to belong to this class of materials [1,2,3].

### Condensed Matter Seminar | Senthil Todadri, MIT | "Correlations and topology in graphene moire lattices" | Joseph Henry Room, Jadwin Hall

### Special Condensed Matter Seminar | Han Yan, OIST, Japan, | "Universal picture of holographic toy models from Rank-2 U(1) theory (or Lifshitz gravity)" | PCTS Seminar Room 407

In this talk, we address two points connecting holographic toy models and fracton states of matter. First, we show that there is a unified picture behind different holographic toy models based on tensor-networks, bit threads, and fracton model: a web of bit threads on a hyperbolic lattice.

### Condensed Matter Seminar | Andrey Chubukov, U of Minnesota "Interplay between superconductivity and non-Fermi liquid above a quantum critical point in a metal" | Joseph Henry Room, Jadwin Hall

I discuss the interplay between non-Fermi liquid behaviour and superconductivity near a quantum-critical point (QCP) in a metal. The tendencies towards superconductivity and non-Fermi liquid behaviour compete: fermionic incoherence destroys the Cooper logarithm, while superconductivity eliminates scattering at low energies and restores...

### Condensed Matter Seminar | Klaus Richter, University of Regensburg, Germany | "Probing the Quantum Mechanics of Many-Body Chaos" | PCTS Seminar Room 407

The dynamics and spread of quantum information in complex many-body systems is presently attracting

a lot of attention across various fields, ranging from cold atom physics via condensed quantum matter

to high energy physics and quantum gravity. This includes questions of how a quantum system thermalizes

### Condensed Matter Seminar, Umesh Vazirani, EECS Berkeley, | "Computational Pseudorandomness and Susskind's Wormhole Paradox " | PCTS Seminar Room 407

The AdS/CFT correspondence conjectures a duality between a theory of quantum gravity in Anti de Sitter space and a conformal field theory. Susskind identified an interesting paradox in this correspondence: namely some aspects of the behavior of eternal black holes, which partition space-time into two distinct regions connected by a “wormhole...

### Condensed Matter Seminar | Andrey Gromov, Brown University | "Bimetric theory of fractional quantum Hall states" | Jadwin A08

Fractional quantum Hall (FQH) states are topologically ordered. Additionally, FQH states support a collective neutral excitation known as the Girvin-MacDonald-Platzman (GMP) mode. Certain features of this mode are independent of the microscopic details.

### Efficient Simulation of the Dynamics in Quantum Many-Body Systems - Frank Pollmann - TUM - PCTS

### Exploring the Landscape of Complex Quantum States: From New Phases of Matter to Robust Schemes for Quantum Computation - Sagar Vijay, 303 Jadwin***NEW TIME 1:30***

Abstract: We present recent advances in our understanding of (i) exotic quantum phases of matter in three dimensions, and (ii) robust mechanisms for storing and processing quantum information, that have been enabled by new techniques to study highly-entangled quantum states. First, we introduce new kinds of gapped quantum phases in three...