title: A diffractive mechanism of focusing.
abstract: We examine the free time evolution of a rectangular one dimensional Schrödinger wave packet of constant phase during the early stage which in the paraxial wave approximation is identical to the diffraction of a scalar field from a single slit. Our analysis, based on numerics and the Cornu spiral reveals considerable intricate detail behavior in the density and phase of the wave. We also point out a concentration of the intensity that occurs on axis and propose a new measure of width that expresses this concentration.
authors.affiliation: Department of Physics, Grinnell College, Grinnell, Iowa 50112, USA.
authors.forename: W B
authors.initials: WB
authors.lastname: Case
authors.forename: E
authors.initials: E
authors.lastname: Sadurni
authors.forename: W P
authors.initials: WP
authors.lastname: Schleich
mesh_terms: D000465:Algorithms; D004583:Electrons; D008027:Light; D055095:Optics and Photonics / Q000379:methods*; D011336:Probability; D011789:Quantum Theory; D012542:Scattering, Radiation