Shear and Vorticity in a Combined Einstein-Cartan-Brans-Dicke Inflationary Lambda-Universe

A combined BCDE (Brans-Dicke and Einstein-Cartan) theory with lambda-term is developed through Raychaudhuri's equation, for inflationary scenario. It involves a variable cosmological constant, which decreases with time, jointly with energy density, cosmic pressure, shear, vorticity, and Hubble's parameter, while the scale factor, total spin and scalar field increase exponentially. The post-inflationary fluid resembles a perfect one, though total spin grows, but the angular speed does not (Berman, 2007d). Keywords: Cosmology; Einstein; Brans-Dicke; Cosmological term; Shear; Spin; Vorticity; Inflation; Einstein-Cartan; Torsion. PACS: 04.20.-q ; 98.80.-k ; 98.80.Bp ; 98.80.JkComment: 8 pages including front one. Published versio

Drag effects in the system of electrons and microcavity polaritons

The theory of the drag effects in the system of spatially separated electrons and excitons in coupled quantum wells (QW) embedded in an optical microcavity is developed. It is shown that at low temperature an electron current induces the (normal component) polariton flow, therefore, a transport of photons along the cavity. However, the electron current dragged by the polariton flow is strongly suppressed below polariton superfluid transition temperature and hence, the strong suppression of the induced electron current indicates the superfluidity of polaritons. Therefore, the transport properties of polaritons can be investigated by measuring the current or voltage in the electron subsystem. At high temperatures we study the exciton-electron drag effects. At high temperatures regime, from one hand, the existence of the electric current in an electron QW induces the exciton flow in the other QW, from the other hand, the electron current in one QW induces the exciton flow in the other QW via the drag of excitons by the electrons. The drag coefficients for the polariton-electron systems are calculated and analyzed. We discuss the possible experimental observation of the drag effects in the system of electrons and microcavity polaritons, that also allow to observe the cavity polaritons superfluidity.Comment: 16 pages, 7 figures, Physical Review B, in press (2010

Can we move photons?

The drag effects in the system of spatially separated electrons and excitons in coupled quantum wells (CQWs) embedded in an optical microcavity are predicted. It is shown that at low temperature an electron current induces the polariton flow, therefore, a transport of photons along the cavity. However, the superfluid polariton component does not contribute to the electron drag. The polariton-electron at the low temperatures and exciton-electron at the high temperatures drag coefficients are presented. It is shown that the drag coefficients increase when temperature increases. We discuss possible experiments for the observation of the electron-polariton drag effect.Comment: 5 pages, 2 figure

Theory of collision effects on line shapes using a quantum mechanical description of the atomic center of mass motion - Application to lasers

Quantum mechanical treatment of atomic center of mass motion in theory of collision effects on line shape