The two-leg t-J ladder: a spin liquid generated by Gutzwiller projection   of magnetic bands
  The ground state of the two-leg Heisenberg ladder is identified as an RVB type spin liquid, which is generated by Gutzwiller projection of tight-binding bands with flux pi per plaquet. Explicit trial wave functions for the magnon and hole excitations are formulated in terms of spinons and holons. 
Martin Greiter (Stanford University)