Electron tunneling through narrow gaps between metal nanoparticles can strongly affect the plasmonic response of the hybrid nanostructure. Although quantum mechanical in nature, this effect can be properly taken into account within a classical framework of Maxwell equations using the so-called Quantum Corrected Model (QCM). We extend previous studies on spherical cluster and cylindrical nanowire dimers where the tunneling current occurs in the extremely localized gap regions, and perform quantum mechanical time dependent density functional theory (TDDFT) calculations of the plasmonic response of cylindrical core-shell nanoparticles (nanomatryushkas). In this axially symmetric situation, the tunneling region extends over the entire gap between the metal core and the metallic shell. For core-shell separations below 0.5 nm, the standard classical calculations fail to describe the plasmonic response of the cylindrical nanomatryushka, while the QCM can reproduce the quantum results. Using the QCM we also retrieve the quantum results for the absorption cross section of the spherical nanomatryushka calculated by V. Kulkarni et al. [Nano Lett. 13, 5873 (2013)]. The comparison between the model and the full quantum calculations establishes the applicability of the QCM for a wider range of geometries that hold tunneling gaps.

We obtain the thermodynamic properties for a non-interacting Bose gas constrained on multilayers modeled by a periodic Kronig-Penney delta potential in one direction and allowed to be free in the other two directions. We report Bose-Einstein condensation (BEC) critical temperatures, chemical potential, internal energy, specific heat, and entropy for different values of a dimensionless impenetrability P 0 between layers. The BEC critical temperature Tc coincides with the ideal gas BEC critical temperature T0 when P = 0 and rapidly goes to zero as P increases to infinity for any finite interlayer separation. The specific heat CV vs T for finite P and plane separation a exhibits one minimum and one or two maxima in addition to the BEC, for temperatures larger than Tc which highlights the effects due to particle confinement. Then we discuss a distinctive dimensional crossover of the system through the specific heat behavior driven by the magnitude of P . For T < Tc the crossover is revealed by the change in the slope of log CV (T ) and when T > Tc, it is evidenced by a broad minimum in CV (T ).

The temporal evolution of an electron in a double rectangular quantum dot in the presence of an electric field pulse is explored in this work. In the framework of the effective mass approximation, first-order scattering rates for electron–electron and electron–longitudinal acoustic phonon interaction at room temperature are calculated in the high tunnelling regime, and used to evaluate the dynamics of the population and coherence of the first three confined levels under an electric field pulse. Small values of these rates dependent upon the coupling barrier make feasible the emission of coherent radiation near 0.1 THz.

In this work, the second harmonic generation from excitonic transitions in semiconductor quantum dots is computationally studied. By integrating a density matrix treatment with a partial configuration interaction approach, we obtain the second order susceptibility as a function of externally applied electric and magnetic fields for highly confined neutral and charged excitons. Our results show an enhancement in the nonlinear response with respect to analogous optical processes based on intraband transitions, and predict their efficient tunability by taking advantage of the interplay between Coulomb effects and field-driven wave function manipulation.

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The energy spectrum of twodimensional magnetoexcirons has been calculated using the shined IIN expansion melhod (N the space dimension). It is found that even in the leadingterm approximation this approach provides remarkably accurate and simple analytic expressions For the magnetoexiton energies for any magnetic field strength and electron-hole mass d o . For the infinite-hole-mass exciton (hydmgenic impurity) our results show an excellen1 agreement with previously reported numerical data in the whole magnetic field range. Higher terms in the expansion which allow a systematic improvement of lowenergy values m also considered.

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We study the excitonic effects on the second-order nonlinear optical properties of semi-spherical quantum dots considering, on the same footing, the confinement potential of the electron-hole pair and the Coulomb interaction between them. The exciton is confined in a semi-spherical geometry by means of a three-dimensional semi-parabolic potential. We calculate the optical rectification and second harmonic generation coefficients for two different values of the confinement frequency based on the numerically computed energies and wavefunctions of the exciton. We present the results as a function of the incident photon energy for GaAs/AlGaAs quantum dots ranging from few nanometers to tens of nanometers. We find that the second-order nonlinear coefficients exhibit not only a blue-shift of the order of meV but also a change of intensity compared with the results obtained ignoring the Coulomb interaction in the so-called strong-confinement limit.