The quantum dynamics of the periodically-driven infinite square well is examined. This simple system illustrates some important aspects of quantum chaos. The phase space structure of the quantum eigenstates are shown to mimic the structure of the classical phase space and these eigenstates show a transition from “regular” to “chaotic” as the strength of the driving field is increased. The spaci...

We study scattering properties of a PT -symmetric square well potential with real depth larger than the threshold of particle-antiparticle pair production as the time component of a vector potential in the Dirac equation. Spontaneous pair production inside the well becomes tiny beyond the strength at which discrete bound states with real energies disappear, consistently with a spontaneous break...

We have measured magnetotransport at half-filled high Landau levels in a quantum well with two occupied electric subbands. We find resistivities that are isotropic in perpendicular magnetic field but become strongly anisotropic at nu = 9/2 and 11/2 on tilting the field. The anisotropy appears at an in-plane field, B(ip) approximately 2.5 T, with the easy-current direction parallel to B(ip) but ...

The PT-symmetric square well problem is considered in a SUSY framework. When the coupling strength Z lies below the critical value Z (crit) 0 where PT symmetry becomes spontaneously broken, we find a hierarchy of SUSY partner potentials, depicting an unbroken SUSY situation and reducing to the family of sec2-like potentials in the Z → 0 limit. For Z above Z 0 , there is a rich diversity of SUSY...

A non stationary state in the one-dimensional infinite square well formed by a combination of the ground state and the first excited one is considered. The statistical complexity and the Fisher-Shannon entropy in position and momentum are calculated with time for this system. These measures are compared with the Heisenberg uncertainty relation, ∆x∆p. It is observed that the extreme values of ∆x...

objective: the aim of this study was to evaluate the efficacy of enamel bonding agents on pit and fissure sealant retention in a well-isolated situation. materials and methods: thirty-two patients (6-9 years old, all males) with four fully erupted permanent first molars were selected. their occlusal, buccal, and lingual fissures were sealed according to a split-mouth design using concise light ...

The role of bottom friction and the fluid layer depth in numerical simulations and experiments of freely decaying quasi-two-dimensional turbulence in shallow fluid layers has been investigated. In particular, the power-law behavior of the compensated kinetic energy E0(t)=E(t)e(2lambda t), with E(t) the total kinetic energy of the flow and lambda the bottom-drag coefficient, and the compensated ...

Michael D. Hirschhorn For some years Jacobi’s two and four squares theorems (stated below) have been sources of considerable fascination to me, so much so that I have continually sought the simplest, most direct proofs of them. Indeed, I have in the past presented two proofs of each [1,2,3,4]. It is my intention to give now what I regard as even simpler proofs of these two theorems as well as r...

We describe the time evolution of a wave function in the infinite square well using a fractional revival formalism, and show that at all times the wave function can be described as a superposition of translated copies of the initial wave function. Using the model of a wave form propagating on a dispersionless string from classical mechanics to describe these translations, we connect the reflect...

Recently, it has been demonstrated [Magee, Phys. Rev. Lett. 96, 207802 (2006)] that isolated square-well homopolymers can spontaneously break chiral symmetry and "freeze" into helical structures at sufficiently low temperatures. This behavior is interesting because the square-well homopolymer is itself achiral. In this work, we use event-driven molecular dynamics combined with an optimized para...