Multi-stability in an optomechanical system with two-component Bose-Einstein condensate

We investigate a system consisting of a two-component Bose-Einstein condensate interacting dispersively with a Fabry-Perot optical cavity where the two components of the condensate are resonantly coupled to each other by another classical field. The key feature of this system is that the atomic motional degrees of freedom and the internal pseudo-spin degrees of freedom are coupled to the cavity field simultaneously, hence an effective spin-orbital coupling within the condensate is induced by the cavity. The interplay among the atomic center- of-mass motion, the atomic collective spin and the cavity field leads to a strong nonlinearity, resulting in multi- stable behavior in both matter wave and light wave at the few-photon level.Comment: 4 pages, 3 figure

Looking behind Granger causality

Granger causality as a popular concept in time series analysis is widely applied in empirical research. The interpretation of Granger causality tests in a cause-effect context is, however, often unclear or even controversial, so that the causality label has faded away. Textbooks carefully warn that Granger causality does not imply true causality and preferably refer the Granger causality test to a forecasting technique. Applying theory of inferred causation, we develop in this paper a method to uncover causal structures behind Granger causality. In this way we re-substantialize the causal attribution in Granger causality through providing an causal explanation to the conditional dependence manifested in Granger causality.Granger Causality; Time Series Causal Model; Graphical Model

THE TRANSITION PROCESS IN CHINA: AN ECONOMIC DEVELOPMENT PERSPECTIVE

During the last 25 years, the Chinese economy has experienced significant changes: the centrally planned economy has been reformed gradually into a market economy; the traditional agricultural economy is becoming more and more a modern industrial economy. In a dynamic two-sector-two-segment model we demonstrate that the economic reform has changed the industrialization mechanism in China. It released a decentralized industrialization process beside the centrally planned Soviet-type industrialization. This decentralized industrialization is shown to be the ultimate driving force of the transition from plan to market in China.Transition, Economic Reform, Industrialization, the Chinese Economy

A graphical method of estimating heat capacities of hydrocarbons

Heat capacity arises because the individual particles comprising a substance are able to move and thus take up kinetic energy and usually also potential energy as the temperature rises. In many substances electrons do not absorb energy until very high temperatures are reached. Thus most heat capacity effects are interpreted in terms of the motion of the atoms neglecting electronic transitions. The total internal energy of a material is, therefore, equal to the sum of the energies due to translational and rotational motion of the molecules and to the vibrational motion of the atoms making up the molecules...The objective of this investigation is to search for the relationship among the F factors of hydrocarbons, and use this relationship to develop a graphical method of determining heat capacities of the hydrocarbons --Introduction, page 1-2

Analyses on deformation and fracture evolution of zonal disintegration during axial overloading in 3D geomechanical model tests

To investigate the formation of zonal disintegration phenomenon in deep rock mass under high axial geostress, 3D geomechanical model tests for two rock strengths are carried out via capacity of deep rock breakage mechanics and supporting technique model test. Considering the maximum principal stress along the tunnel axis, 3D geomechanical model tests are carried out in a loading procedure of first loading to initial geostress, then excavating the tunnel with blasting construction, and finally overloading the stress along the tunnel. Due to unloading effect, radial strain is tensile and tangential strain is compressive around excavated tunnel after excavation complete, which indicates a radial tension and circumferential compression stress state. With continuous overloading of axial stress, values of both radial tensile strain and tangential compressive strain increase, then ring fracture appears due to large radial tensile strain. After axial overloading, an interval distribution of peaks and troughs is shown in radial tensile strain distribution around excavated tunnel, which indicates a formation of zonal disintegration. By cutting the rectangular cemented sand model, a distinct zonal disintegration phenomenon emerges, and an apparent shrinkage of excavated tunnel is also shown due to radial deformation towards excavated tunnel. The larger the rock strength is, the less the tunnel shrinkage is, the smaller the radius of fracture zone. After statistical analyses of three ring tensile fracture zones, the radius scale factor of fracture zone in zonal disintegration is about 1.28

Ultrafast Molecular Spectroscopy Using a Hollow-Core Photonic Crystal Fibre Light Source

We demonstrate, for the first time, the application of rare-gas filled hollow-core photonic crystal fibres (HC-PCFs) as tuneable ultraviolet light sources in femtosecond pump-probe spectroscopy. The time-resolved photoelectron imaging technique reveals non-adiabatic dynamical processes operating on three distinct timescales in the styrene molecule following excitation over the 242-258 nm region. These include ultrafast (<100 fs) internal conversion between the S2(pipi*) and S1(pipi*) electronic states and subsequent intramolecular vibrational energy redistribution within S1(pipi*). Compact, cost-effective and highly efficient bench-top HC-PCF sources have huge potential to open up many exciting new avenues for ultrafast spectroscopy in the ultraviolet and vacuum ultraviolet spectral regions. We anticipate that our initial validation of this approach will generate important impetus in this are

Quantum state transmission via a spin ladder as a robust data bus

We explore the physical mechanism to coherently transfer the quantum information of spin by connecting two spins to an isotropic antiferromagnetic spin ladder system as data bus. Due to a large spin gap existing in such a perfect medium, the effective Hamiltonian of the two connected spins can be archived as that of Heisenberg type, which possesses a ground state with maximal entanglement. We show that the effective coupling strength is inversely proportional to the distance of the two spins and thus the quantum information can be transferred between the two spins separated by a longer distance, i.e. the characteristic time of quantum state transferring linearly depends on the distance.Comment: 7 pages, 5 figures, 1 tabl