2,933 research outputs found
Ground-state properties of bosons in three- and two-dimensional traps
We study trapped systems of bosons at zero temperature in three and two
dimensions. Conditions are fulfilled for the application of Gross-Pitaevskii
theory with a positive scattering length. Series expansions for ground-state
properties are obtained in both the noninteracting and the strong-coupling
(Thomas-Fermi) limits. From these expansions, analytic estimates are presented
in the form of two-point Pad\'e approximants. We explicitly show the
approximants for the total energy per particle and the chemical potential.Comment: LaTeX, 4 pages, 3 ps figure
Renormalised perturbative series for the impurity levels in a quantum well
The energy levels of an impurity center in a deep quantum well of width L and
depth g are studied analytically . Renormalised perturbative series are
constructed in the regions g L^ > 1. Maximal binding energy and
wave function deformation to a quasi-twodimensional function are found to occur
at a certain L_c satisfying sqrt{g} L_c ~ 1. Similar results may be obtained
for the impurity in a quantum wire, in a dot or in a multiwell structure.Comment: 11 pages. LaTeX. 3 figures not include
Discontinuities in the level density of small quantum dots under strong magnetic fields
Exact diagonalization studies of the level density in a six-electron quantum
dot under magnetic fields around 7 T (``filling factor'' around 1/2) are
reported. In any spin-polarization channel, two regimes are visible in the dot
excitation spectrum: one corresponding to interacting quasiparticles (i.e.
composite fermions) for excitation energies below 0.4 meV, and a second one for
energies above 0.4 meV, in which the level density (exponentially) increases at
the same rate as in the non-interacting composite-fermion model.Comment: Accepted in Phys. Rev.
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