Superfluidity of the lattice anyon gas and topological invariance

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Abstract

I consider a gas of free anyons with statistical parameter, with hard cores, on a two-dimensional square lattice. Using a recently derived Jordan-Wigner transformation, I map this problem onto a gas of fermions on the same lattice coupled to a Chern-Simons gauge theory with coupling =1/2. At the semiclassical level, the system is found to be equivalent to a gas of fermions, with the same density, in an average effective magnetic field /. I consider the case in which an integer number of the Landau bands of the saddle-point problem are completely filled. If =/m and the density =r/q, with m, r, and q integers, the system is a superfluid, provided that q is larger than twice the largest common factor of m and r. If q is even and the system is half filled, the state may be either a superfluid or a quantum Hall phase. For all other values of and, compatible with integer filling of the Landau bands, the system is in a quantum Hall phase. The dynamical stability of the superfluid state is ensured by the topological invariance of the quantized Hall conductance of the fermion problem. I find a close analogy between anyon superconductivity and the Schwinger mechanism. The effective Lagrangian for the low-energy modes coupled to the electromagnetic field is derived. The energies of fermion and flux states are logarithmically divergent, but finite for the anyon state. The system has flux quantization, a zero-temperature Hall effect with a quantized Hall conductance, Meissner effect, charged vortices, screening with induced magnetic fields for static charges, and different masses for the longitudinal and transverse components of the electromagnetic field.

Original languageEnglish (US)
Pages (from-to)570-586
Number of pages17
JournalPhysical Review B
Volume42
Issue number1
DOIs
StatePublished - Jan 1 1990

ASJC Scopus subject areas

  • Condensed Matter Physics

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