Clemson University

Colloquium: Dr. Tobias Grass


Department of Physics and Astronomy

Kinard 101, Lecture Hall

Monday, January 14th, 4:00 pm



Topological matter controlled by light


Tobias Grass


JQI/ University of Maryland


Abstract: Topological matter provides quantum many-body systems which stand out through extremely robust transport properties and exotic emergent quasiparticles. In my talk, I will discuss different strategies in which light-matter interactions are used to probe, prepare, and manipulate the behavior of topological systems. In this context, I will consider electronic quantum Hall systems, including semiconducting quantum well system and graphene, in which topological behavior is caused by a strong magnetic field, as well as cold atomic gases in which the topological phases are fully synthesized via optical and/or mechanical control. Specifically, I will show for a graphene quantum Hall system that the chirality of excitations at the edge is revealed by photocurrent measurements. Pumping light with orbital angular momentum into the system offers the possibility of creating anyonic bulk excitations. Periodic driving can be used to induce topological phase transitions, and to prepare very rich non-Abelian phases. In an atomic system, the shape of the inter-atomic potential can be controlled by coupling the atomic ground state to one or several Rydberg levels. This can lead to novel phases in which symmetry-broken order and topological order appear to coexist.


Bio: Dr. Grass got his PhD in physics in 2013 from Insitut de Ciéncies Fotóniques (ICFO), Barcelona (Spain) studying ultracold atoms in artificial gauge fields with a strong focus on the fractional quantum Hall effect of atoms. From 2013 to 2016, he continued at ICFO as a post-doctoral researcher, working on atomic quantum simulators as solvers of spin models, e.g., via quantum annealing. Since September 2016, he is a postdoctoral fellow at the Joint Quantum Institute in Maryland. In collaboration with local experimental groups (trapped ions lab at JQI, semiconductor quantum optics lab at NIST Gaithersburg) and theoretical groups (A. Gorshkov, M. Hafezi, both JQI/UMD/NIST), he studies quantum-optical control in a variety of many-body systems.


Refreshments will be served afterwards in the PandA Café.

Monday, January 14 at 4:00pm to 5:00pm

Kinard Laboratory of Physics, 101 Kinard Lab
140 Delta Epsilon Ct., Clemson, SC 29634, USA

Event Type

Lectures / Seminars / Speakers


College of Science, Physics and Astronomy

Target Audience

Students, Faculty, Undergraduate, Graduate

Contact Name:

Amanda Ellenburg

Contact Phone:


Contact Email:





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