420,625 research outputs found
Width of the charge-transfer peak in the SU(N) impurity Anderson model and its relevance to nonequilibrium transport
We calculate the width 2ÎCT and intensity of the charge-transfer peak (the one lying at the on-site energy Ed) in the impurity spectral density of states as a function of Ed in the SU(N) impurity Anderson model (IAM). We use the dynamical density-matrix renormalization group (DDMRG) and the noncrossing approximation (NCA) for N=4 and a 1/N variational approximation in the general case. In particular, while for Ed Î, where Î is the resonant level half-width, ÎCT=Î as expected in the noninteracting case, for Ed NÎ one has ÎCT=NÎ. In the N=2 case, some effects of the variation of ÎCT with Ed were observed in the conductance through a quantum dot connected asymmetrically to conducting leads at finite bias [J. Könemann, Phys. Rev. B 73, 033313 (2006)PRBMDO1098-012110.1103/PhysRevB.73.033313]. More dramatic effects are expected in similar experiments that can be carried out in systems of two quantum dots, carbon nanotubes or other, realizing the SU(4) IAM.Fil: FernĂĄndez, JoaquĂn. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Patagonia Norte; Argentina. ComisiĂłn Nacional de EnergĂa AtĂłmica. Gerencia del Ărea de EnergĂa Nuclear. Instituto Balseiro; ArgentinaFil: Lisandrini, Franco Thomas. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Rosario. Instituto de FĂsica de Rosario. Universidad Nacional de Rosario. Instituto de FĂsica de Rosario; ArgentinaFil: Roura Bas, Pablo Gines. ComisiĂłn Nacional de EnergĂa AtĂłmica. Centro AtĂłmico Constituyentes; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Gazza, Claudio Javier. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Rosario. Instituto de FĂsica de Rosario. Universidad Nacional de Rosario. Instituto de FĂsica de Rosario; ArgentinaFil: Aligia, Armando Ăngel. ComisiĂłn Nacional de EnergĂa AtĂłmica. Gerencia del Ărea de EnergĂa Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Patagonia Norte; Argentin
Spectral Singularities with Directional Sensitivity
We propose a class of spectral singularities that are sensitive to the direction of excitation and arise in nonlinear systems with broken parity symmetry. These spectral singularities are sensitive to the direction of the incident beam and result in diverging transmission and reflection for the left (right) incident, while the transmission and reflection of the right (left) side of the system remain finite. For the pedagogical reason, first we review the scattering formalism in nonlinear systems using an abstract ÎŽ-function model. Then, using a parity symmetry broken nonlinear system consisting of two ÎŽ functions, one linear and the other nonlinear, we prove the existence of our proposed spectral singularities. Finally, we use an experimentally feasible realistic model based on coupled disk resonators to demonstrate the spectral singularity with directional sensitivity (SSDS). Our proposed SSDS might have applications in the design of nonlinear sensors and might provide a solution for the hole-burning problem in pumped laser ring resonators
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