My question is motivated from the paper Boundary degeneracy of topological order by Juven Wang and Xiao Gang Wen.
Consider a (2+1)D system with boundary, described by abelian Chern-Simons theory. Due to the bulk-boundary correspondence, its boundary is described by chiral boson CFT.
In page 2 of the paper, the authors discuss on the condensation of anyons. Some excerpts from the paper are:
If particles condense on the boundary due to the interactions of edge modes, it can introduce mass gap to the edge modes.
A set of particles can condense on the same boundary if they do not have relative quantum fluctuation phases with each other, thus all condensed particles are stabilized in the classical sense. It requires that condensed particles have relative zero braiding statistical phase.
I am having hard time understanding the meaning of condensation. What I know about condensation is Bose-Einstein condensation, where macroscopic number of particles occupy the same state.
Questions:
What does it mean by the condensation of particles on the edge? Is it analogous to the familiar Bose-Einstein condensation? Why condensation introduces mass gap to the edge modes?
Why condensing set of particles is possible if they do not have relative quantum fluctuation phases with each other? Before this question, what is the "relative quantum fluctuation phases"?
What does it mean that the condensed particles are stabilized in the classical sense?
Partial answers, or introductory references on the condensation of anyons are also appreciated.
