Screening of electrostatic potential in a composite fermion system

Screening of the electric field of a test charge by monolayer and double-layer composite fermion systems is considered. It is shown that the electric field of the test charge is partly screened at distances much large then the magnetic length. The value of screening as a function of the distance depends considerably on the filling factor. The effect of variation of the value of screening in the double-layer system upon a transition to a state described by the Halperin wave function is determined.Comment: 5 pages, 2 eps figures include

Grafted Rods: A Tilting Phase Transition

A tilting phase transition is predicted for systems comprising rod like molecules which are irreversibly grafted to a flat surface, so that the non interacting rods are perpendicularly oriented. The transition is controlled by the grafting density $\rho$. It occurs as $\rho$ increases as a result of the interplay between two energies. Tilt is favoured by the van-der-Waals attraction between the rods. It is opposed by the bending elasticity of the grafting functionality. The role of temperature is discussed, and the tilting mechanism is compared to other tilting transitions reported in the literature.Comment: 21 pages, 2 figures, to appear in Journal de Physique I

Interaction of quantum Hall systems with waveguide elastic modes

An interaction of non-uniform plane elastic modes of the waveguide type with monolayer and double-layer quantum Hall systems is considered. It is shown, that unlike the case of the surface acoustic wave propagation, the restriction on maximal values of the wave vectors for which the velocity shift can be observed experimentally does not take place for the waveguide modes. In case of study of incompressible fractional quantum Hall states the effect can be used for measuring a dependence of the effective magnetic length on the filling factor and for observing phase transitions in double-layer system under the interlayer distance variationComment: 6 pages, 3 eps figures included, Fig.1 and Fig.3 correcte

Conductance beyond the Landauer limit and charge pumping in quantum wires

Periodically driven systems, which can be described by Floquet theory, have been proposed to show characteristic behavior that is distinct from static Hamiltonians. Floquet theory proposes to describe such periodically driven systems in terms of states that are indexed by a photon number in addition to the usual Hilbert space of the system. We propose a way to measure directly this additional Floquet degree of freedom by the measurement of the DC conductance of a single channel quantum point contact. Specifically, we show that a single channel wire augmented with a grating structure when irradiated with microwave radiation can show a DC conductance above the limit of one conductance quantum set by the Landauer formula. Another interesting feature of the proposed system is that being non-adiabatic in character, it can be used to pump a strong gate-voltage dependent photo-current even with linearly polarized radiation.Comment: 9 pages; 3 figures: Final published version; includes minor revisions from the last versio

Entanglement Spectrum and Entanglement Thermodynamics of Quantum Hall Bilayers at nu=1

We study the entanglement spectra of bilayer quantum Hall systems at total filling factor nu=1. In the interlayer-coherent phase at layer separations smaller than a critical value, the entanglement spectra show a striking similarity to the energy spectra of the corresponding monolayer systems around half filling. The transition to the incoherent phase can be followed in terms of low-lying entanglement levels. Finally, we describe the connection between those two types of spectra in terms of an effective temperature leading to relations for the entanglement entropy which are in full analogy to canonical thermodynamics.Comment: New findings in Eqs.(5)-(8) and pertaining discussion, and addendum to the title, version as publishe

The Tomonaga-Luttinger Model and the Chern-Simons Theory for the Edges of Multi-layer Fractional Quantum Hall Systems

Wen's chiral Tomonaga-Luttinger model for the edge of an m-layer quantum Hall system of total filling factor nu=m/(pm +- 1) with even p, is derived as a random-phase approximation of the Chern-Simons theory for these states. The theory allows for a description of edges both in and out of equilibrium, including their collective excitation spectrum and the tunneling exponent into the edge. While the tunneling exponent is insensitive to the details of a nu=m/(pm + 1) edge, it tends to decrease when a nu=m/(pm - 1) edge is taken out of equilibrium. The applicability of the theory to fractional quantum Hall states in a single layer is discussed.Comment: 15 page