Events Archive

Condensed Matter Seminar | Helen Bouchiat, U of Paris Sud | "Revealing the second-order topological character of bismuth-based Josephson junction" | Joseph Henry Room
Wed, Feb 19, 2020, 12:00 pm12:00 pm

 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]. Just like the case of Quantum Spin Hall edges of 2D Topological Insulators,…

Condensed Matter Seminar | Senthil Todadri, MIT | "Correlations and topology in graphene moire lattices" | Joseph Henry Room, Jadwin Hall
Wed, Dec 4, 2019, 12:00 pm12:00 pm


A remarkable recent development is the discovery of correlated electronic states in twisted bilayer graphene and other moire graphene systems. In this talk I will discuss aspects of the  theory of these systems. I will show that both strong correlations and band topology are features of many graphene moire lattices. I will…
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
Thu, Nov 21, 2019, 1:30 pm1:30 pm

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. They all capture some coarse features of the…

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
Wed, Nov 20, 2019, 12:00 pm12:00 pm

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…

Condensed Matter Seminar | Klaus Richter, University of Regensburg, Germany | "Probing the Quantum Mechanics of Many-Body Chaos" | PCTS Seminar Room 407
Mon, Sep 23, 2019, 1:15 pm1:15 pm

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
and phenomena like…

Condensed Matter Seminar, Umesh Vazirani, EECS Berkeley, | "Computational Pseudorandomness and Susskind's Wormhole Paradox " | PCTS Seminar Room 407
Mon, Sep 9, 2019, 1:15 pm1:15 pm

 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
Mon, Mar 25, 2019, 1:15 pm2:55 pm

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. The objective of the talk is to construct an effective theory includes both topological…

Efficient Simulation of the Dynamics in Quantum Many-Body Systems - Frank Pollmann - TUM - PCTS
Mon, Feb 11, 2019, 1:00 pm1:00 pm
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***
Wed, Feb 6, 2019, 1:30 pm1:30 pm

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"
Mon, Feb 4, 2019, 2:00 pm3:00 pm

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.

In the first part of the talk, the method for microscopic construction of symmetry adapted…

Exploring synthetic quantum matter in superconducting circuits
Mon, Jan 21, 2019, 1:00 pm1:00 pm

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. We develop a versatile recipe that…

Special Condensed Matter Seminar | Cheng Ju Lin, Caltech | "Exact Strong-ETH Violating Eigenstates in the Rydberg-blockaded Atom Chain" | PCTS Seminar Room 407
Thu, Nov 15, 2018, 2:55 pm2:55 pm

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. In the same nonintegrable…

Condensed Matter Seminar | Hassan Shaporian, U of Oregan | "Topological invariants and entanglement in SPT phases of fermions" | Jadwin 303
Mon, Oct 29, 2018, 1:15 pm1:15 pm

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. I introduce a general…

Special Condensed Matter Seminar | Maciej Koch-Janusz, ETH Zurich | "Machine learning and the renormalization group" | Jadwin 343
Fri, Oct 5, 2018, 1:30 pm1:30 pm

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
Mon, Sep 24, 2018, 1:15 pm1:15 pm

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]. The Hall number (remarkably) generally depends solely on equilibrium thermodynamic susceptibilities,…

Special Condensed Matter Seminar | Johannes Zeiher, Max Planck | "Microscopy of Rydberg-dressed quantum gases" | PCTS Seminar Room 407
Mon, May 21, 2018, 1:15 pm1:15 pm


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.

In our experiment, we…

Special Condensed Matter Seminar | Yan Sun, Max Planck | "Linear response in topological semimetals" | Jadwin 303
Mon, May 14, 2018, 1:15 pm1:15 pm

Abstract:  We have found that the strong spin Hall effect in TaAs is mainly dominated from the Weyl points and nodal-line-like Fermi surface, which implying a strong interplay between the topological band structure and Berry curvature in topological semimetals. With this guiding principle, we have successfully understood the strong spin Hall…

Special Condensed Matter Seminar | Prof. Guido Burkard, Konstanz U. | "Electric-dipole control and coupling of spin qubits" | PCTS Seminar Room 407
Tue, May 8, 2018, 1:30 pm1:30 pm


Spin qubits in dilute nuclear-spin materials such as silicon and carbon are currently among the most coherent systems for quantum information processing.

Yet, while the small magnetic moment associated with electron spins provides excellent shielding of the…

Condensed Matter Seminar | Philip Phillips, UIUC | "Anomalous Dimensions for Conserved Currents and Extra Dimensions in the Strange Metal?" | Jadwin PCTS Seminar Room 407
Mon, Apr 16, 2018, 1:15 pm1:15 pm

Abstract:  It is well known that conserved quantities cannot have anomalous dimensions.  However, a recent proposal for the ubiquitous strange metal phase in the cuprates argues just the opposite.  Namely,  all of the properties of such `strange metals' can be understood if the current has an anomalous dimension.   My talk will focus on trying…

Special Condensed Matter Seminar | Rudolf Grimm, UIBK | "Impurities in an ultracold Fermi sea: Quasiparticles, phase separation and beyond" | Jadwin 111
Tue, Apr 10, 2018, 1:30 pm1:30 pm

Abstract:  Impurity physics has emerged as a new branch of research in the field of atomic quantum gases. A central feature is the wide tunability of interactions between the impurities and the surrounding medium. By using magnetically controlled Feshbach resonances, regimes of strong interactions can be reached which reveal intriguing many…