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Confining Potential (confining + potential)
Selected AbstractsSymmetry breaking and Wigner molecules in few-electron quantum dotsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2006Constantine Yannouleas Abstract We discuss symmetry breaking in two-dimensional quantum dots resulting from strong interelectron repulsion relative to the zero-point kinetic energy associated with the confining potential. Such symmetry breaking leads to the emergence of crystalline arrangements of electrons in the dot. The so-called Wigner molecules form already at field-free conditions. The appearance of rotating Wigner molecules in circular dots under high magnetic field, and their relation to magic angular momenta and quantum-Hall-effect fractional fillings is also discussed. Recent calculations for two electrons in an elliptic quantum dot, using exact diagonalization and an approximate generalized-Heitler,London treatment, show that the electrons can localize and form a molecular dimer for screened interelectron repulsion. The calculated singlet-triplet splitting (J ) as a function of the magnetic field (B ) agrees with cotunneling measurements; its behavior reflects the effective dissociation of the dimer for large B . Knowledge of the dot shape and of J (B ) allows determination of two measures of entanglement (concurrence and von Neumann entropy for indistinguishable fermions), whose behavior correlates also with the dissociation of the dimer. The theoretical value for the concurrence at B = 0 agrees with the experimental estimates. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Transverse Stark effect of electrons in a semiconducting quantum wirePHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 3 2003G. J. Vázquez Abstract We investigate the effect of an electric field applied tranversely to the axis of cylindrical symmetry of a cylindrical quantum wire on the ground-state energy of the electrons in the wire using an infinite confining potential well model. For low electric fields, we find a quadratic shift of the energy levels with the electric field; while for strong fields, the Stark shift of the ground-state energy increases almost linearly with the electric field. This increase is greater for wide wires, but for narrow wires, the Stark shift of the ground-state energy does not change much with the electric field. Also, at higher electric fields, the Stark shift of the ground-state energy increases with increasing wire radius. This will lead to the decrease of the effective bandgap of a semiconducting quantum wire with electric field. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Lattice modes in a system of charge rotators in a plasma environmentPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 11 2004S. V. Vladimirov Abstract Three dimensional rotatory modes of oscillations in a one-dimensional chain of rod-like charged particles or dust grains in a plasma are investigated. An oscillatory dependence on wavenumber and a critical dependence on the relative strengths of the confining potential is found. The characteristic frequency range for the oscillatory modes is of the order of the dust plasma frequency. The azimuthal and colatitudinal modes show opposite characteristics in the near and far interparticle distance regimes, respectively. The rods are shown to move, or switch to the relevant equilibrium, dependind on the confining parameters. This is an example of a phase change phenomenon which is analogous to that observed in liquid crystals. The ability to line up rods in different directions, by alternating the relative sizes of the confining potentials, is a powerful tool for applications. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Spherical quantum dot under an electric fieldPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue S1 2004Gerardo J. Vázquez Abstract We investigate the effect of an electric field applied to a spherical quantum dot on the energy groundstate of carriers in the quantum dot using an infinite confining potential well model. We perform a simple variational calculation for low electric fields and we find a quadratic shift of the energy levels with the electric field while for strong fields, the Stark shift of the energy groundstate increases almost linearly with the electric field. There is a transition for quasi-one dimensional to three-dimensional behavior when the dot radius is large. The comparison of our results with previous exact calculations is very good. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Lattice modes in a system of charge rotators in a plasma environmentPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 11 2004S. V. Vladimirov Abstract Three dimensional rotatory modes of oscillations in a one-dimensional chain of rod-like charged particles or dust grains in a plasma are investigated. An oscillatory dependence on wavenumber and a critical dependence on the relative strengths of the confining potential is found. The characteristic frequency range for the oscillatory modes is of the order of the dust plasma frequency. The azimuthal and colatitudinal modes show opposite characteristics in the near and far interparticle distance regimes, respectively. The rods are shown to move, or switch to the relevant equilibrium, dependind on the confining parameters. This is an example of a phase change phenomenon which is analogous to that observed in liquid crystals. The ability to line up rods in different directions, by alternating the relative sizes of the confining potentials, is a powerful tool for applications. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||