Ryan Thorngren's Webpage


I'm a physicist with a background in mathematics, interested in symmetry, topology, and beyond-perturbative methods in many-body systems, from quantum condensed matter and statistical mechanics to high-energy physics. This is my personal website. A group website is in progress!

We are running a CMT Journal Club on Wednesdays at 11am (intro talk) and 4pm (research talk) in the Schwinger lounge. Email me and I will add you to the email list.

I am admin of the anomalology discord. Send me an email and I will send you an invite! We are just restarting the zoom seminar.

I am part of the Simons Collaboration on Global Categorical Symmetries.

You can contact me at first dot last at physics dot ucla dot edu and you can find me in Knudsen 6-137C.

Recent and Upcoming

With Lei Gioia we recently proved that the W-state is not the unique ground state of any local Hamiltonian, for a precise but very flexible class of lattice Hamiltonians. I'm very fascinated by this groundstatability result, as it may constrain the search space for quantum ground states, and I know of no other result of this kind so far!

With Arun Debray, Sanath K. Devalapurkar, Cameron Krulewski, Yu Leon Liu, Natalia Pacheco-Tallaj, we just posted a new paper on anomalies at domain walls, vortices, hedgehogs, etc. and a long exact sequence which encodes their matching with the bulk anomaly and higher Berry phase. I'm very excited about this work, and more to come from this interdisciplinary collaboration! You can hear me talk about some of it here and here is another talk by Leon and Cam.

I am teaching Ph231a in the Fall, which will be about complex analysis, differential equations, asymptotics and perturbation theory, a bit of differential topology, and other fun stuff.

Romain Geiko has joined our (small) group as a postdoc!

With R. Verresen, U. Borla, T. Rakovsky, S. Moroz, and A. Vishwanath we are finishing a work showing how the Higgs phase of a gauge theory is naturally an SPT. Here is the preprint of volume I! And here is volume II!

Things I'm Thinking About

Higgs-SPT ideas in non-abelian gauge theories and superconductors.

The "self-dual" critical point in the Fradkin-Shenker phase diagram.

Higher Berry phases and their experimental realization.

"Quantum cellular automata" and how they relate to gapped phases.

Mixed state or "average" SPTs.


John McGreevy's course notes

Online topological condensed matter course

Other Stuff

The background of this page draws a randomly selected 5-state cellular automata, where a pixel's state depends only on the average of the previous state of itself and its two neighbors. There are 5^13 such rules.

Here is a picture of me on a sand dune in Death Valley, excited to have found some scale invariant criticality in the wild! My hair is not as long now :)