Topological phases of matter cannot be characterized by any
pattern of symmetry-breaking, so describing phase transitions between
them is a significant theoretical challenge. In the case of non-
Abelian phases, there are only a few examples of phase transitions
that are theoretically understood. In this talk I will describe a
series of phase transitions between well-known bilayer Abelian
fractional quantum Hall (FQH) states -- the (ppq) states -- and a
series of non-Abelian FQH states. An example of this transition is
between the (330) state and the non-Abelian Z4 parafermion state,
driven by increasing interlayer tunneling and/or interlayer repulsion.
Previously used methods have failed because the transition from these
states appears to be driven by the condensation of anyons. After
presenting a recently developed effective field theory for the non-
Abelian states, I will explain how it can be used, along with other
methods, to shed light on the nature of these transitions. |