UNIVERSAL JUMPS OF CONDUCTANCE AT THE METAL-INSULATOR-TRANSITION IN ONE DIMENSION

The transition for a one-dimensional collection of spinless interacting charged particles from metal to a Mott insulator phase is shown to exhibit two kinds of universal jump of conductance: when the filling factor is p/q, where p and q are irreducible integers and q gives the order of backward scattering responsible for localization, there is a jump e2/q2h along the metal-insulator phase boundary, but at special points with particle-hole symmetry the universal jump of conductance is exactly twice as large. Even far inside the metal phase, where the Mott insulator does not occur, its existence is manifested by a singularity in the conductance at the corresponding rational filling. Most of the results hold also for the case of Mott localization in a quasiperiodic potential. The only essential difference here is that insulator phases are characterized by filling factors which are, in general, irrational numbers: for a quasiperiodic potential with a ratio of fundamental incommensurate length a the insulator phase is characterized by an irrational filling factor (m0 + m1sigma)/q, where m0,1 are integers.