Fractional helical liquids in quantum wires

We study one-dimensional wires with spin-orbit coupling. We show that in the presence of Zeeman field and strong electron-electron interaction a clean wire may form fractional helical liquid states with phenomenology similar to fractional quantum Hall liquids. Most notably, the wire's two-terminal conductance is predicted to show fractional quantized conductance plateaus at low electron density. When the system is proximity coupled to a superconductor, fractional Majorana bound states may be stabilized, giving rise to a one-dimensional analog of non-Abelian anyons. We discuss how disorder destabilizes these fractional phases. Possible experimental realizations of similar states in double wire systems are discussed.