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...

# Events Archive

## Condensed Matter Seminar

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

### 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...

### Condensed Matter Seminar: Oskar Vafek-FSU-"Strong Coupling Phases of Partially Filled Twisted Bilayer Graphene Narrow Bands"

When the twist angle of a bilayer graphene is commensurate and near the `magic' value, there are four narrow bands near the neutrality point, each two-fold spin degenerate. These bands are separated from the rest of the bands by energy gaps.

### Exploring synthetic quantum matter in superconducting circuits

Superconducting circuits have emerged as a competitive platform for quantum computation, satisfying the challenges of controllability, long coherence and strong interactions. Here we apply this toolbox to a different problem: the exploration of strongly correlated quantum materials made of microwave photons.

### Special Condensed Matter Seminar | Cheng Ju Lin, Caltech | "Exact Strong-ETH Violating Eigenstates in the Rydberg-blockaded Atom Chain" | PCTS Seminar Room 407

Abstract: A recent experiment in the Rydberg atom chain observed unusual oscillatory quench dynamics with a charge density wave initial state, and theoretical works identified a set of many-body ``scar states'' in the Hamiltonian as potentially responsible for the atypical dynamics.

### Condensed Matter Seminar | Hassan Shaporian, U of Oregan | "Topological invariants and entanglement in SPT phases of fermions" | Jadwin 303

Searching for a proper set of order parameters which distinguish different phases of matter sits in the heart of condensed matter physics. In this talk, I discuss topological invariants as (non-local) order parameters of symmetry protected topological (SPT) phases of fermions in the presence of anti-unitary symmetries.

### Special Condensed Matter Seminar | Maciej Koch-Janusz, ETH Zurich | "Machine learning and the renormalization group" | Jadwin 343

Physical systems differing in their microscopic details often display strikingly similar behaviour when probed at macroscopic scales. Those universal properties, largely determining their physical characteristics, are revealed by the renormalization group (RG) procedure, which systematically retains ‘slow’ degrees of freedom and integrates out...

### Condensed Matter Seminar | Assa Auerbach, Technion | “Hall number of strongly correlated metals”| PCTS Seminar Room 407

A convergent summation formula for the DC Hall number of strongly correlated and disordered metals is derived from the Kubo formula. Properties of Bogoliubov operator Hilbert space are used for the derivation [1].

### Special Condensed Matter Seminar | Johannes Zeiher, Max Planck | "Microscopy of Rydberg-dressed quantum gases" | PCTS Seminar Room 407

Abstract:

Off-resonant optical coupling of an atomic ground state to a Rydberg state, so-called "Rydberg-dressing", has been proposed as a versatile method to implement various long-range interacting spin models with ultracold atoms.