We studied the thermal and magnetic properties of a cylindrical quantum dot in the presence of external electric and magnetic fields. The energy spectrum and wave functions for the quantum dot of asymmetric confinement are obtained by solving the Schrödinger wave equation analytically. The energy levels are employed to calculate the canonical partition function, which in turn is used to obtain specific heat, entropy, magnetization, and susceptibility. These thermal and magnetic quantities are found to have direct dependence on confinement length, magnetic field, and temperature, thus the parameters of the system can be tuned to fit into more than one application. PACS Nos.: 78.40.Fy, 75.75.-c, 68.65.Hb. Résumé : Nous étudions ici les propriétés thermiques et magnétiques de points quantiques cylindriques en présence de champs électriques et magnétiques externes. Nous solutionnons analytiquement l'équation de Schrödinger pour le spectre en énergie et les fonctions d'ondes de ce point quantique de confinement asymétrique. Les énergies propres permettent de calculer la fonction de partition canonique qui nous donne la capacité calorifique, l'entropie, la magnétisation et la susceptibilité. Nous trouvons que ces quantités thermiques et magnétiques dépendent directement de la longueur de confinement, du champ magnétique et de la température et qu'ainsi les paramètres du système peuvent être accordés pour satisfaire plus d'une application. [Traduit par la Rédaction]

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Recently, multiphoton processes in nanostructures have attracted much attention for their promising applications, especially in growing field of bioimaging. Here we investigate the optical response of quantum disc (QD) in the presence of laser and a static magnetic field. Floquet theory is employed to solve the equation of motion for laser driven intraband transitions between the states of the conduction band. Several interesting features namely dynamic stark shift, power broadening, and hole burning on excited levels degeneracy breaking are observed with variation of electric and magnetic field strengths. Enhancement and power broadening observed for excited states probabilities with increase of external fields are directly linked to the emission spectra of QD and will be useful for making future bioimaging devices.

The influence of Rashba spin orbit interaction on the optical properties of two dimensional mesoscopic ring has been investigated in the presence of uniform perpendicular magnetic field. The Schrodinger equation for the Rashba coupled system is solved by effective mass approximation and diagonalization technique. Using the calculated energies and eigenfunctions, the laser field induced change in refractive index and optical absorption have been studied under the density matrix formalism. It has been found that Rashba spin orbit interaction removes the intersection of energy levels; however, avoided crossings are observed at finite magnetic field. At sufficient high values of Rashba coupling or laser intensity, the optical response of quantum ring is found to be dominated by third order nonlinear term. Also, Rashba interaction shifts the value of magnetic field that is needed to suppress the absorption drastically and to pass the incident light unattenuated. The results reveal that the geometry of the ring plays an important role in determining the magnitude of nonlinear absorption coefficient and change in refractive index which enable us to design the device with optimum efficiency.

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