# Events Archive

## Condensed Matter Seminar

### Special CM Seminar, Aris Alexandradinata, Yale, "The first nonsymmorphic topological insulator: prediction and discovery"

Wed, Jun 8, 2016, 1:30 pm to 3:00 pm

Spatial symmetries in crystals are distinguished by whether they preserve the spatial origin. I will show how this basic geometric property gives rise to a new topology in band insulators, which we propose (and subsequently discover) to lie in the large-gap insulators: KHgX (X=As,Sb,Bi).

### Special Seminar: Edoardo Baldini, EPFL Lausanne, Switzerland, "Exploring the Nonequilibrium Dynamics of Collective Excitations"

Mon, Jun 6, 2016, 1:30 pm to 2:30 pm

One of the distinctive characteristics of strongly interacting and correlated quantum systems is the non-trivial interplay between low- and high-energy degrees of freedom. The origin of this interplay lies in the electron-electron and electron-boson interactions, which spread the optical spectral weight over a wide energy range.

### Special CM Seminar, Ahmet Avsar, National University of Singapore, "Electronic spin transport in gate-tunable black phosphorus spin valves"

Fri, Jun 3, 2016, 1:00 pm to 2:00 pm

### Special Condensed Matter Seminar, Gregor Jotzu, ETH, "Probing Topological Floquet-Bands and Quantum Magnetism with Ultracold Fermions"

Fri, May 20, 2016, 1:30 pm to 3:00 pm

Complex quantum many-body systems are ubiquitous in nature, yet their behaviour often remains very challenging to predict with analytical or numerical calculations - especially when it comes to dynamics.

### Special CM Seminar, Shaffique Adam, Yale-NUS, "The role of electron-electron interactions in graphene†"

Wed, May 18, 2016, 1:30 pm to 3:00 pm

About ten years ago, a new electronic material appeared – notable not only for its ease of preparation and theoretical simplicity, but also by its promise for future electronic devices. Single monatomic sheets of carbon, known as graphene, are described as weakly interacting massless Dirac fermions and in many ways, are a textbook system to test...

### Condensed Matter Seminar, Dmitri Khevshchenko, UNC, "Demystifying the Holographic Mystique"

Mon, May 16, 2016, 1:15 pm to 2:30 pm

Thus far, in spite of many interesting developments,
the overall progress towards a systematic study and classification of various 'strange' metallic states of matter has been rather limited. To that end, it was argued that a recent proliferation of the ideas of

### Special CM Seminar, Thomas Iadecola, Boston College, "Wire constructions of Abelian topological phases in three or more dimensions"

Thu, May 12, 2016, 1:30 pm to 3:00 pm

Coupled-wire constructions have proven to be useful tools to characterize Abelian and non-Abelian topological states of matter in two spatial dimensions. In many cases, their success has been complemented by the vast arsenal of other theoretical tools available to study such systems. In three dimensions, however, much less is known about...

### Condensed Matter Seminar, Roderich Moessner, Max Planck, "Dynamics of a Kitaev spin liquid"

Mon, May 9, 2016, 1:15 pm to 2:30 pm

The excitation spectra of topological phases of matter contain rather
`direct' information about their unusual quasiparticles, while the
corresponding bulk ground states tend to be rather
featureless. Motivated by this observation, we have evaluated the
dynamical structure factor of the Kitaev model on the honeycomb

### Condensed Matter Seminar, Chetan Nayak, Microsoft, "Floquet Time Crystals: Spontaneously Broken Discrete Time-Translational Symmetry in Periodically-D

Mon, May 2, 2016, 1:15 pm to 2:30 pm

I will define what it means for time translation symmetry to be spontaneously broken in a quantum system, and show with analytical arguments and numerical simulations that this occurs in a large class of driven systems with discrete time-translation symmetry.

### Condensed Matter Seminar, Qimiao Si, Rice U., "Frustrated Magnetism and Superconductivity in Iron Pnictides and Chalcogenides"

Mon, Apr 18, 2016, 1:15 pm to 2:30 pm

This talk will provide a brief overview of the field of the iron-based superconductivity (FeSC), and discuss several topical issues. In the beginning of the field, iron pnictides were the focus of attention.

### Condensed Matter Seminar, Monika Aidelsburger, Col. of France, "Artificial gauge fields and topology with ultracold atoms in optical lattices"

Mon, Apr 4, 2016, 12:00 pm to 1:30 pm

Many intriguing condensed matter phenomena such as the integer and fractional quantum Hall effect arise due to the non-trivial topological properties of the underlying system. Synthetic materials

### Special Condensed Matter Seminar, Panagiotis Kotetes, U. of Copenhagen, "Signatures of Majorana fermions in Shiba chains with or without spin-orbit in

Thu, Mar 31, 2016, 2:00 pm to 3:30 pm

Recent spin polarized scanning tunneling microscopy (SPSTM) experiments in magnetic chains [1] opened new routes for detecting the elusive Majorana fermions (MFs). Within the deep Shiba limit we calculate [2] the spatially resolved tunneling conductance of topological ferromagnetic chains [1,3] measurable by means of SPSTM.

### Condensed Matter Seminar, Michael Gullans, NIST/U. of MD, " Quantum Nonlinear Optics"

Thu, Mar 24, 2016, 12:00 pm to 1:00 pm

In the semiclassical theory of nonlinear optics, the nonlinear response of the medium is typically treated perturbatively and characterized in terms of just a few phenomenological parameters. The remaining task, in this case, is to measure these coefficients as a function of frequency, wavevector, temperature, etc. However, when the medium...

### Special Condensed Matter Seminar, Alexey Soluyanov, ETH, "New Topological Excitations"

Wed, Mar 23, 2016, 1:30 pm to 3:00 pm

In recent years it was realized that our knowledge of possible quasiparticle excitations is incomplete even for non-interacting systems. I will talk about several novel topological excitations that appear in metals. One of them realizes a new type of Weyl fermion, hosting the behavior very different from its standard quantum field theory...

### Condensed Matter Seminar, Haim Beidenkopf, Weizmann Institute, "Tantalizing Fermi arcs in a Weyl semi-metal"

Mon, Mar 21, 2016, 1:15 pm to 2:30 pm

A defining property of a topological material is the existence of surface bands that cannot be realized but as the termination of a topological bulk. In a Weyl semi-metal these are given by the surface Fermi-arcs, whose open-contour Fermi-surface curves between pairs of surface projections of bulk Weyl points of opposite chirality.

### Special Condensed Matter Seminar, Chaoxing Liu, Penn State, “Possible realization of bosonic symmetry protected topological phases in bilayer graphe

Tue, Mar 8, 2016, 1:30 pm to 2:30 pm

Ever since the discovery of time reversal invariant topological insulators, intensive research interests are focused on how to identify new topological phases that are protected by symmetry (known as symmetry protected topological states) and how to search for new topological materials to realize these topological phases.

### Special CMS, Michael Brenner, Harvard, "Towards artificial living materials"

Wed, Feb 24, 2016, 2:30 pm to 4:00 pm

Biological systems provide an inspiration for creating a new paradigm for materials synthesis. Imagine it were possible to create an inanimate material that could both perform some function, e.g. catalyze a set of reactions, and also self replicate.

### Condensed Matter Seminar, Steve Kivelson, Stanford, "Electron Nematic Phases in Highly Correlated Electron Systems"

Mon, Feb 22, 2016, 1:15 pm to 2:30 pm

Phases of the strongly interacting electron fluid which spontaneously break the point-group symmetries of the host crystal can sometimes be characterized as “electron nematic phases.” Such phases increasingly appear to play a significant role in the physics of a variety of “interesting” materials, including the Cu and Fe based high temperature...

### Special CM Seminar, Felix Flicker, UC Berkeley, "Charge Order, Quasicrystals, and the Quantum Hall Effect"

Thu, Jan 7, 2016, 1:30 pm to 3:00 pm

Recent experimental observations have been argued to demonstrate that one-dimensional quasicrystals - quasiperiodic slices through two-dimensional crystals - adopt the topological quantum numbers of their higher-dimensional parent lattice, exhibiting an equivalent to the quantum Hall effect.

### Special Condensed Matter Physics Seminar - Stefan Putz, TU Wien - "Circuit Cavity QED with Collective Spin States"

Thu, Dec 10, 2015, 11:00 am to 12:00 pm

In this talk I will present recent progress in examining collective spin phenomena’s such as cavity protection, spectral hole burning and amplitude bi-stability in a hybrid solid state system consisting of a superconducting microwave cavity strongly coupled to an ensemble of electron spins in nitrogen-vacancy centers in diamond.