161 research outputs found
Shape transitions in excited states of two-electron quantum dots in a magnetic field
We use entanglement to study shape transitions in two-electron axially symmetric parabolic quantum dots in a perpendicular magnetic field. At a specific magnetic field value the dot attains a spherical symmetry. The transition from the axial to the spherical symmetry manifests itself as a drastic change of the entanglement of the lowest state with zero angular momentum projection. While the electrons in such a state are always localized in the plane (x-y) before the transition point, after this point they become localized in the vertical direction.Fil: Nazmitdinov, R.G.. Bogoliubov Laboratory Of Theoretical Physics, Joint Institute For Nuclear Research; Rusia. Universitat de Les Illes Balears; EspañaFil: Simonovic, N. S.. University of Belgrade; SerbiaFil: Plastino, Ángel Ricardo. Comisión de Regulación de Energía y Gas; Argentina. Universidad Nacional de La Plata; Argentina. Universidad de Granada; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Chizhov, A.V.. Bogoliubov Laboratory Of Theoretical Physics, Joint Institute For Nuclear Research; Rusi
Modifying the photodetachment near a metal surface by a weak electric field
We show the photodetachment cross sections of H near a metal surface can be
modified using a weak static electric field. The modification is possible
because the oscillatory part of the cross section near a metal surface is
directly connected with the transit-time and the action of the
detached-electron closed-orbit which can be changed systematically by varying
the static electric field strength. Photodetachment cross sections for various
photon energies and electric field values are calculated and displayed.Comment: 16 pages, 7 figure
Classical Coulomb three-body problem in collinear eZe configuration
Classical dynamics of two-electron atom and ions H, He, Li,
Be,... in collinear eZe configuration is investigated. It is revealed
that the mass ratio between necleus and electron plays an important role
for dynamical behaviour of these systems. With the aid of analytical tool and
numeircal computation, it is shown that thanks to large mass ratio ,
classical dynamics of these systems is fully chaotic, probably hyperbolic.
Experimental manifestation of this finding is also proposed.Comment: Largely rewritten. 21 pages. All figures are available in
http://ace.phys.h.kyoto-u.ac.jp/~sano/3-body/index.htm
Quantum over-barrier reflection effects manifested in the photodetachment cross sections
Photodetachment of H near a potential barrier is studied. A new formula
is presented for the cross sections induced by a barrier. The new formula
describes two quantum effects near barrier tops. For energies near and above
barrier tops, the quantum over-barrier reflection effects are included and the
induced oscillations in the cross sections are still prominent; for energies
near and below barrier tops, the quantum tunneling across barriers is taken
into account and consequently the oscillations are weakened. For energies far
away from the barrier tops, the new formula agrees with the standard
closed-orbit theory. We demonstrate that a potential barrier of various width
and location can be realized by placing a negative ion near a metal surface and
applying an electric field pointing to the surface. The width and location of
the barrier can be systematically changed by varying the electric field
strength and the distance between the negative ion and the surface. Results are
also presented for estimating the sizes and locations of aforementioned quantum
effects in the cross sections
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