Barry Bradlyn

Assistant Professor

Contact

Barry Bradlyn

Primary Research Area

  • Condensed Matter Physics
2129 Engineering Sciences Building
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Biography

Professor Bradlyn received his bachelor's degree in Physics from the Massachusetts Institute of Technology in 2009. He went on to receive his Ph.D. from Yale University in 2015, under the supervision of Nicholas Read. His thesis research focused on linear response and Berry phases in the fractional quantum Hall effect. His primary contributions was the development of a formalism for computing the viscoelastic and thermal response functions for two dimensional Topological phases.

From 2015 to 2018, Professor Bradlyn held a postdoctoral research position at the Princeton Center for Theoretical Science, where he studied the role of crystal symmetries in topological insulators and semimetals. He predicted the existence of topologically charged, multiply degenerate fermions in weakly interacting crystals with no known analogue in high energy physics. Additionally, he developed a real-space formulation of topological band theory, allowing for the prediction of many new topological insulators and semimetals.

Professor Bradlyn joined the physics department at the University of Illinois in 2018.

Research Interests

  • symmetry protected topological semimetals
  • geometric response in condensed matter
  • the quantum Hall effect
  • topological insulators

Research Statement

One of the most exciting developments in condensed matter physics over the last thirty years has been the discovery of topological phases of matter. Under the broadest possible definition, a system is in a topological phase if there is a gap in its bulk spectrum. Of course, such a definition describes any ordinary thermal or electrical insulator. The key theoretical breakthrough was the realization that not all insulators are created equal. In fact, given a model for an insulating system, there exist certain numerical invariants - topological quantum numbers - that we can compute in order to distinguish between different possible topological phases. These invariants vanish for most ordinary insulators (strictly speaking, they take the same values as in the vacuum) - they are "topologically trivial". The distinguishing feature of such topological invariants is that they depend on the global structure of the system under consideration; topological phases are not locally ordered like magnets or solids. Consequently, systems in nontrivial topological phases are host to a wide range of exotic phenomena, from quantized transport coefficients to fractional bulk excitations that harbor the potential to allow for fault tolerant quantum computation.

Since this initial discovery, the influence of topology has spread across all areas of condensed matter physics. It is this--in addition to individual realizations of topological phases--that is in my opinion the biggest boon of this new paradigm. Topology now stands alongside abstract algebra (as it pertains, for instance, to symmetry groups) as one of our main tools for exploring quantum phenomena in solids and liquids. Broadly speaking, the goal of my research is to marry ideas from these two areas in order to study new phenomena in condensed matter. Currently, I am focusing on the following main topics:

1. Viscous and optical response of topological insulators and semimetals

2. Magnetic topological materials

3. Crystal symmetry protected topological phenomena

Research Honors

  • McMillan Award (August 2019)
  • Facebook Content Policy Research on Social Media Platforms Research Award (May 2019)

Selected Articles in Journals

Related news

  • Research
  • Condensed Matter Physics
  • Condensed Matter Theory

Scientists at the Max Planck Institute for Chemical Physics of Solids in Dresden, Princeton University, the University of Illinois at Urbana-Champaign, and the University of the Chinese Academy of Sciences have spotted the fingerprint of an elusive particle: The axion—first predicted 42 years ago as an elementary particle in extensions of the standard model of particle physics. Based on predictions from Illinois Physics Professor Barry Bradlyn and Princeton Physics Professor Andrei Bernevig's group, the group of Chemical Physics Professor Claudia Felser at Max Planck in Dresden produced the charge density wave Weyl metalloid (TaSe4)2I and investigated the electrical conduction in this material under the influence of electric and magnetic fields. It was found that the electric current in this material below -11 °C is actually carried by axion particles.

  • Research
  • Outreach

Illinois Physics Professor Barry Bradlyn and his colleague, State University of New York at Binghamton Computer Science Professor Jeremy Blackburn, have been awarded a Facebook research grant to trace the propagation and dissemination of hate speech on social media.

  • Research
  • Condensed Matter Physics

Researchers at the Paul Scherrer Institute in Switzerland working with scientists at institutions in Germany, Great Britain, Spain, and the US, have investigated a novel crystalline material, a chiral semimetal, exhibiting never-before-seen electronic properties. These include so-called chiral Rarita-Schwinger fermions in the interior and very long, quadruple topological Fermi arcs on the surface. The crystal, synthesized at the Max Planck Institute for Chemical Physics of Solids in Dresden, Germany, comprises aluminum and platinum atoms arranged in a helical pattern, like a spiral staircase. It’s the crystal’s chiral symmetry that hosts exotic emergent electronic properties.

These research findings, published online in the journal Nature Physics on May 6, 2019, validate a 2016 theoretical prediction by University of Illinois Physics Professor Barry Bradlyn (then a postdoc at the Princeton Center for Theoretical Science), et al., in the journal Science (vol. 353, no. 6299, aaf5037). That theoretical work was subsequently rounded out by a team of physicists at Princeton University, in research published in 2017 and 2018.