Charge and spin quantum fluids generated by many-electron interactions Original Research Article

In this paper we describe the electrons of the non-perturbative one-dimensional (1D) Hubbard model by a fluid of unpaired rotated electrons and a fluid of zero-spin rotated-electron pairs. The rotated electrons are related to the original electrons by a mere unitary transformation. For all finite values of energy and for the whole parameter space of the model this two-fluid picture leads to a description of the energy eigenstates in terms of occupancy configurations of η-spin 1/2 holons, spin 1/2 spinons, and c pseudoparticles only. The electronic degrees of freedom couple to external charge (and spin) probes through the holons and c pseudoparticles (and spinons). Our results refer to very large values of the number of lattice sites Na. The holon (and spinon) charge (and spin) transport is made by 2ν-holon (and 2ν-spinon) composite pseudoparticles such that ν=1,2,… . For electronic numbers obeying the inequalities N⩽Na and N↓⩽N↑ there are no zero-spin rotated-electron pairs in the ground state and the unpaired-rotated-electron fluid is described by a charge c pseudoparticle fluid and a spin ν=1 two-spinon pseudoparticle fluid. The spin two-spinon pseudoparticle fluid is the 1D realization of the two-dimensional resonating valence bond spin fluid.