Bianchi I cosmology and preferred reference frames effect

We consider Brans-Dicke (BD) scalar-vector-tensor gravity to study an inflationary scenario of the accelerating expanding Universe with anisotropy. To do so we use Bianchi I background metric which its spatial part has cylindrical symmetry. Applying comoving frame to solve dynamical field equations. Our solutions describe a non-singular exponentially inflationary accelerating expanding Universe in presence of a linear form of self interacting the Brans Dicke scalar field and kinetic energy of the used dynamical vector field. Also we obtain a power-law accelerating expanding singular cosmological model with a power law self interacting the Brans Dicke scalar field. Our solutions predict that the spatial anisotropy of the cosmic space time does not stopped but continues with a decreasing rate. All solutions satisfy observational data such as e-folds number of the inflation, scalar spectral index and etc. Furthermore we obtained an one-dimensional non-singular non-accelerating expanding Dirac-Milne model by setting some suitable values on the parameters of the metric solutions.Comment: 19 pages, 4 figure and some minor revisio

Quantumness and memory of one qubit in a dissipative cavity under classical control

Hybrid quantum–classical systems constitute a promising architecture for useful control strategies of quantum systems by means of a classical device. Here we provide a comprehensive study of the dynamics of various manifestations of quantumness with memory effects, identified by non-Markovianity, for a qubit controlled by a classical field and embedded in a leaky cavity. We consider both Leggett–Garg inequality and quantum witness as experimentally-friendly indicators of quantumness, also studying the geometric phase of the evolved (noisy) quantum state. We show that, under resonant qubit-classical field interaction, a stronger coupling to the classical control leads to enhancement of quantumness despite a disappearance of non-Markovianity. Differently, increasing the qubit-field detuning (out-of-resonance) reduces the nonclassical behavior of the qubit while recovering non-Markovian features. We then find that the qubit geometric phase can be remarkably preserved irrespective of the cavity spectral width via strong coupling to the classical field. The controllable interaction with the classical field inhibits the effective time-dependent decay rate of the open qubit. These results supply practical insights towards a classical harnessing of quantum properties in a quantum information scenari

Factors contributing to the fluctuations in residential construction in Iran

Residential construction is one of the most important pillars of Iran’s economy. Although this sector had an increasing trend over the past two decades, however, the growth rate of residential construction was very volatile. The purpose of this paper is to empirically investigate those factors contributing to this fluctuation over the 1991:Q2-2008:Q4. By applying cointegration approach, the empirical results show that housing prices, construction costs, GDP and gold prices are important factors to explain swings in residential construction in Iran. &nbsp