Remote detection in abelian fracton phases - Quantum Matter SeminarConfirmed

by Evan Wickenden (University of Colorado, Boulder)

Thursday Dec 4, 2025, 3:00 PM → 4:30 PM America/Toronto

VIRTUAL ONLY (Perimeter Institute for Theoretical Physics)

Gapped phases without symmetry are largely characterized by the fusion and statistics of their fractionalized quasiparticles. This is best understood for 2D topological phases. An important constraint on statistical data in this case is the principle of remote detectability, which implies that any nontrivial anyon braids nontrivially with another anyon in the system.

The principle of remote detectability can be applied to more general gapped phases. In 3D topological phases, for example, fully mobile point particles cannot braid nontrivially with each other, but the principle is rescued by the existence of loop excitations. In 3D fracton phases, by contrast, there need not exist loop excitations, but point quasiparticles have restricted mobility, so the principle can still hold. However, fracton phases exhibit many possible patterns of mobility restriction, and it is not yet understood how to parameterize the inequivalent “braidings” that may be compatible with a given fusion theory.

In this talk, I will describe recent progress on this problem. I will introduce the class of planon- modular fracton orders—phases in which every excitation can be detected by braiding with a planon—and highlight several structural consequences of this definition. I will then focus on the case with only abelian planon excitations, where remote detectability is strengthened to a more rigid statistical constraint that we call the excitation-detector principle. I will present new classi- fication results that follow from this principle. Finally, I will describe how these ideas extend to a framework for characterizing braiding and remote detection in general abelian fracton orders, and in abelian gapped phases more broadly.