Steve Simon

Abstract:

There is growing experimental and theoretical evidence that very clean two-dimensional electron systems form unidirectional charge density waves (UCDW) or "striped" states at low temperatures and at Landau level filling fractions of the form v = M + x with 4 < M < 10 an integer and 0.4 ≳ x ≳ 0.6. Following previous work, we model the striped state using a Hartree-Fock approach. We construct the low-energy excitations of the system by making smooth deformations of the stripe edges analogous to the construction of edge state excitations of quantum Hall droplets. These low-energy excitations are described as a coupled Luttinger liquid theory, as discussed previously by MacDonald and Fisher [Phys. Rev. B 61, 5724 (2000)]. Here, we extend that work and explicitly derive all of the parameters of this low energy theory using a Hartree-Fock approach. We also make contact with the equivalent low-energy hydrodynamic approach of Fogler and Vinokur [Phys. Rev. Lett. 84, 5828 (2000)] and similarly derive the parameters of this theory. As examples of the use of these results, we explicitly calculate the low-energy excitation spectrum and study tunneling into the striped state.

Abstract:

The effect of scattering on the information transfer rate for cell phones and wireless microwave communication devices was analyzed. The antennas in the array measures the relative phase and amplitude of the signal arriving from the particular source and then transmits with the same relative amplitude but with opposite phase. It is found that the scattering instead of decreasing the efficiency, increases the information transfer rate for wireless communication devices.