J Cai

Long-time divergence in perturbative response theory for weak-field dc conductivity

Abstract We demonstrate that the perturbative expansion of the current density in powers of the electric field in the Kubo linear response theory is divergent in the limit of time t a ∞, and the divergent contributions cannot be summed to give a unique result.

EXACT GROUND-STATE SOLUTION FOR ANYONS WITH SPIN-1/2

We solve the problem of anyons with spin- in an external field and obtain one of exact wavefunctions for its ground state, which is highly degenerated. Using Laughlins plasma analogy, we find that there exists the algebraic off-diagonal long-range order for the ground state wavefunction in a certain external magnetic field.

Linear AC Conductivity Matrix of a Potential-Modulated System: Hydrodynamic-Type Balance Equation Approach*

We obtain the linear AC conductivity matrices for time- and space-dependent fields by means of hydrodynamic-type balance equations. The result is useful for studying the transport properties of a periodically potential-modulated system.

High-Frequency Hoping Conductivity in a Two-Dimensional Antiferromagnetic Lattice*

The optical properties of two-dimensional antiferromagnetic lattice were studied through the theoretical calculation of the high-frequency hoping conductivity in a spin-density-wave background. The effect of the strong spin correlation in the bag excitation region on the conductivity is discussed. Calculations have been made under the mean-field approximation including self-energy and vertex contributions.

Balance Equations for Quantum Tunneling

We have established a set of balance equations to demonstrate the hot electron effect in the quantum tunneling processes by using the well-known effective tunneling Hamiltonian model. The high field effects both in reservoirs and in barrier region are discussed in detail. We also find a new field-dependent characteristic time due to nonequilibrium of reservoirs (the left- and right-sides of the barrier region) in the double-barrier structure.

Failure of Two-Dimensional Plasmonic Mechanism of Superconductivity*

The two-dimensional plasmonic mechanism of superconductivity has been studied by solving the momentum- and frequency-dependent eigenvalue equation containing vertex and self-energy corrections. Our result shows the failure of appearing superconductivity in one-component electron system. The Coulomb interaction including plasmon effects in the electron gas is estimated to yield net repulsive values of between 0.24 and 0.6 for , between 1 and 10.

Balance Equation Approach to Nonlinear Polaronic Transport

Balance equations beyond the lowest order perturbation expansion for high-field electronic transport are developed and used to discuss the polaronic resistivity in polar semiconductors and other systems. Significant corrections in the case of high electric field are expected.