arXiv subjects

J. C. Wallet

Publications and source records attributed to J. C. Wallet.

8 recordsLinked to original sources

arXiv2008

Construction of potentials using mixed scattering data

The long-standing problem of constructing a potential from mixed scattering data is discussed. We first consider the fixed-$\ell$ inverse scattering problem. We show that the zeros of the regular solution of the Schrödinger equation, $r_{n}(E)$ which are monotonic functions of the energy, determine a unique potential when the domain of energy is such that the $r_{n}(E)$'s range from zero to infinity. The latter method is applied to the domain $\{E \geq E_0, \ell=\ell_0 \} \cup \{E=E_0, \ell \geq \ell_0 \}$ for which the zeros of the regular solution are monotonic in both parts of the domain and still range from zero to infinity. Our analysis suggests that a unique potential can be obtained from the mixed scattering data $\{δ(\ell_0,k), k \geq k_0 \} \cup \{δ(\ell,k_0), \ell \geq \ell_0 \}$ provided that certain integrability conditions required for the fixed $\ell$-problem, are fulfilled. The uniqueness is demonstrated using the JWKB approximation.

math-ph↗

arXiv2006

Fractional Quantum Hall States in Fast Rotating Bose Gases

We use a Chern Simons Landau-Ginzburg (CSLG) framework related to hierarchies of composite bosons to describe 2D harmonically trapped fast rotating Bose gases in Fractional Quantum Hall Effect (FQHE) states. The predicted values for $ν$ (ratio of particle to vortex numbers) are $ν$$=$${{p}\over{q}}$ ($p$, $q$ are any integers) with even product $pq$, including numerically favored values previously found and predicting a richer set of values. We show that those values can be understood from a bosonic analog of the law of the corresponding states relevant to the electronic FQHE. A tentative global phase diagram for the bosonic system for $ν$$<$1 is also proposed.

cond-mat.mes-hall↗

arXiv2006

Anyonic Excitations in Fast Rotating Bose Gases Revisited

The role of anyonic excitations in fast rotating harmonically trapped Bose gases in a fractional Quantum Hall state is examined. Standard Chern-Simons anyons as well as "non standard" anyons obtained from a statistical interaction having Maxwell-Chern-Simons dynamics and suitable non minimal coupling to matter are considered. Their respective ability to stabilize attractive Bose gases under fast rotation in the thermodynamical limit is studied. Stability can be obtained for standard anyons while for non standard anyons, stability requires that the range of the corresponding statistical interaction does not exceed the typical wavelenght of the atoms.

cond-mat.mes-hall↗

arXiv2005

Anyonic Excitations in Fast Rotating Bose Gases

The role of anyonic excitations in fast rotating harmonically trapped Bose gases in a fractional Quantum Hall State is examined. Standard Chern-Simons anyons as well as "non standard" anyons obtained from a statistical interaction having Maxwell-Chern-Simons dynamics and suitable non minimal coupling to matter are considered. Their respective ability to stabilize attractive Bose gases under fast rotation in the thermodynamical limit is studied. Stability can be obtained for standard anyons while for non standard anyons, stability requires that the range of the corresponding statistical interaction does not exceed the typical wavelength for the atoms.

cond-mat.mes-hall↗

arXiv2005

Geometrical and Algebraic Structures in Quantum Hall Systems

We review the main features of a mathematical framework encompassing some of the salient quantum mechanical and geometrical aspects of Hall systems with finite size and general boundary conditions. Geometrical as well as algebraic structures controlling possibly the integral or fractional quantization of the Hall conductivity are discussed.

cond-mat.mes-hall↗

arXiv2004

Vortex in Maxwell-Chern-Simons models coupled to external backgrounds

We consider Maxwell-Chern-Simons models involving different non-minimal coupling terms to a non relativistic massive scalar and further coupled to an external uniform background charge. We study how these models can be constrained to support static radially symmetric vortex configurations saturating the lower bound for the energy. Models involving Zeeman-type coupling support such vortices provided the potential has a "symmetry breaking" form and a relation between parameters holds. In models where minimal coupling is supplemented by magnetic and electric field dependant coupling terms, non trivial vortex configurations minimizing the energy occur only when a non linear potential is introduced. The corresponding vortices are studied numerically

cond-mat.other↗

arXiv1998

Experimental evidence for a power law in electroencephalographic $α$-wave dynamics

We perform an experimental study of the time behavior of the $α$-wave events occuring in human electroencephalographic signals. We find that the fraction of the time spent in an $α$-burst of time size $τ$ exhibits a scaling behavior as a function of $τ$. The corresponding exponent is equal to 1.75$\pm$0.13. We therefore point out the existence of a new power law appearing in physiology. Furhtermore, we show that our experimental result may have a possible explanation within a class of Self-Organized Critical (SOC) models recently proposed by Boettcher and Paczuski. In particular, one of these models, when properly re-interpreted, seems to be consistent both with our result and a commonly accepted physiological description of the possible origin of $α$-wave events.

physics.bio-ph↗

arXiv1996

The group $Γ(2)$ and the fractional quantum hall effect

We analyze the action of the inhomogeneous modular group $Γ(2)$ on the three cusps of its principal fundamental domain in the Poincare half plane. From this, we obtain an exhaustive classification of the fractional quantum Hall numbers. This classification is somehow similar to the one given by Jain. We also present some resulting remarks concerning direct phase transitions between the different quantum Hall states.

cond-mat↗