Microscopic theory of quantum dot interactions with quantum light: local field effect

A theory of both linear and nonlinear electromagnetic response of a single QD exposed to quantum light, accounting the depolarization induced local--field has been developed. Based on the microscopic Hamiltonian accounting for the electron--hole exchange interaction, an effective two--body Hamiltonian has been derived and expressed in terms of the incident electric field, with a separate term describing the QD depolarization. The quantum equations of motion have been formulated and solved with the Hamiltonian for various types of the QD excitation, such as Fock qubit, coherent fields, vacuum state of electromagnetic field and light with arbitrary photonic state distribution. For a QD exposed to coherent light, we predict the appearance of two oscillatory regimes in the Rabi effect separated by the bifurcation. In the first regime, the standard collapse--revivals phenomenon do not reveal itself and the QD population inversion is found to be negative, while in the second one, the collapse--revivals picture is found to be strongly distorted as compared with that predicted by the standard Jaynes-Cummings model. %The model developed can easily be extended to %%electromagnetic excitation. For the case of QD interaction with arbitrary quantum light state in the linear regime, it has been shown that the local field induce a fine structure of the absorbtion spectrum. Instead of a single line with frequency corresponding to which the exciton transition frequency, a duplet is appeared with one component shifted by the amount of the local field coupling parameter. It has been demonstrated the strong light--mater coupling regime arises in the weak-field limit. A physical interpretation of the predicted effects has been proposed.Comment: 14 pages, 7 figure

Thermal Radiation From Carbon Nanotube in Terahertz Range

The thermal radiation from an isolated finite-length carbon nanotube (CNT) is theoretically investigated both in near- and far-field zones. The formation of the discrete spectrum in metallic CNTs in the terahertz range is demonstrated due to the reflection of strongly slowed-down surface-plasmon modes from CNT ends. The effect does not appear in semiconductor CNTs. The concept of CNT as a thermal nanoantenna is proposed.Comment: 5 pages, 3 figure

Statistical models of economic burden : a case study in medicine

Purpose: The main aim of this article is to use statistical methods for the estimation of the economic burden and the survival rate of deeply premature babies. Design/Methodology/Approach: The results of a survey of 2.222 children with a birth weight of 501-1500 grams and a gestational age of 23-37 weeks were used as input data. Cox’s proportional hazards model was used as a survival tool. Findings: The results of Cox survival regression model showed a series of statistically significant predictors of survivability (p<0.05) for three age cohorts: neonatal, postnatal and pediatric (until 2 years). One of the statistically significantly predictors of survivability of premature infants with very low birth weight (VLBW) and extremely low birth weight (ELBW) in every age cohort is the volume of primary resuscitation measure and the length of stay in the neonatal pathology unit (NPU). Practical Implications: The results permitted to assess the amount of nursing care measures, the duration of care in a neonatal pathology unit, the rehabilitation of children with VLBW and ELBW in the long run. The assessment will ultimately help to estimate the overall economic burden associated with maintaining health and quality of life of premature babies. Originality/Value: The scientific contribution of the study consists in the use of an integrated approach to the problem of estimating the economic burden of nursing very premature babies, taking into account their survival and subsequent disability risks in the neonatal, postnatal, and pediatric periods.peer-reviewe