Talks

Honey, I shrunk the Magnetic Topological Insulators

The antiferromagnetic topological insulator phase is a foundational re- alization of three-dimensional topological phases of matter with mag- netic order. It is furthermore an example of an axion insulator and condensed matter platform for realizing exotic axion dynamics of high- energy physics. At systems sizes where the sample size is comparable with the correlation length of the topological surface states, it is ex- pected for these states to hybridise. We however show the strength of this hybridisation is oscillatory with respect to system parameters and resonances occur where the surface states can reform. We then confirm the defining response signature of the underlying 3D AFM TI phase persists in this geometry, at these resonances. We then open bound- ary conditions in a second direction to confirm the additional bulk- boundary correspondence of the finite-size topological phases spectral flow, finding q(3-2)D topologically-protected, gapless edge modes. The co-existence of the q(3-2)D topologically non-trivial edge states with a topological response associated with the 3D bulk topological invariant, the magnetoelectric polarizability, confirms finite-size AFM topological phases occur. This further demonstrates that finite-size topology is a generic feature of topological phases and very relevant experimentally.

Tenure Trek: Navigating Academia Around the World

4:30 - 5:30 pm : colloquium "Search as (quantum) selforganized process" by Prof. Dr. Giovanna Morigi 5:30 - 6:00 pm : a coffee break 6:00 - 7:00 pm: Exploring academic systems, gender representation, and career strategies: insights from internationally experienced PIs, followed by a discussion. Abstract for the colloquium: Efficient retrieval of information is a core operation in the world wide web, is essential for the sustainance of living organism, and is a paradigm for optimization algorithms. Inspired by the food search dynamics of living organisms, we discuss a search on a graph with multiple constraints where the dynamics is a selforganized process resulting from the interplay of coherent dynamics and Gaussian noise. We show that Gaussian noise can be beneficial to the search dynamics leading to significantly faster convergence to the optimal solution. We then analyse how these concepts can be extended to quantum searches, cast in terms of spatial searches on a graph and discuss whether and when the efficiency of noise-assisted quantum searches can outperform the one of unitary protocols.

Colloquium

Colloquium

Tunable Matter -- Many More is More Different

In 1972 Phil Andersen articulated the motto of condensed matter physics as “More is different.” However, for most many-body systems the behavior of a trillion bodies is nearly the same as that of a thousand. Here I argue for a class of condensed matter, “tunable matter," in which many more is different. The ultimate example of tunable matter is the brain, whose cognitive capabilities increase as size increases from 302 neurons (C. Elegans) to a million neurons (honeybees) to 100 billion neurons (humans). I propose that tunable matter provides a unifying conceptual framework for understanding not only a wide range of systems that perform biological functions, but also physical systems capable of being trained to develop special collective behaviors without using a processor.

Colloquium