Description:

Discrete scale invariance is the symmetry that fractals show, familiar from
many biological systems.   Manifestations in quantum systems have been
predicted since the 1960s, but experimental proofs have been hard to come by.
In the past few years new materials called topological semimetals have shown
surprising behavior when subjected to very strong magnetic fields B: the electrical
resistance oscillates such that it is periodic in the logarithm of  B.  I'll show that
this comes from bound state spectra that form a geometric sequence, a
sure signature of discrete scale invariance.

Robert Joynt, Professor Emeritus, University of Wisconsin-Madison

Host: Timothy Light Kovachy