Effects of Geometrical Symmetry on the Vortex Nucleation and Penetration in Mesoscopic Superconductors

We investigate how the geometrical symmetry affects the penetration and arrangement of vortices in mesoscopic superconductors using self-consistent Bogoliubov-de Gennes equations. We find that the entrance of the vortex happens when the current density at the hot spots reaches the depairing current density. Through determining the spatial distribution of hot spots, the geometrical symmetry of the superconducting sample influences the nucleation and entrance of vortices. Our results propose one possible experimental approach to control and manipulate the quantum states of mesoscopic superconductors with their topological geometries, and they can be easily generalized to the confined superfluids and Bose-Einstein condensates

Dynamical Creation of Fractionalized Vortices and Vortex Lattices

We investigate dynamic creation of fractionalized half-quantum vortices in Bose-Einstein condensates of sodium atoms. Our simulations show that both individual half-quantum vortices and vortex lattices can be created in rotating optical traps when additional pulsed magnetic trapping potentials are applied. We also find that a distinct periodically modulated spin-density-wave spatial structure is always embedded in square half-quantum vortex lattices; this structure can be conveniently probed by taking absorption images of ballistically expanding cold atoms in a Stern-Gerlach field.Comment: 4 pages, 3 figures; published versio

4′-Formyl­biphenyl-4-yl acetate

In the title compound, C15H12O3, the dihedral angle between the six-membered rings is 30.39 (1)°. The crystal packing is stabilized by inter­molecular C—H⋯O hydrogen bonds

Method for Thermo-optic Analysis in a Star Sensor

An autonomous star sensor is a highly accurate attitude-measuring instrument used in spacecraft, and its performance is restricted by ambient temperature of the outer space. This paper puts forward an effective scheme to the thermooptic analysis using finite element analysis (FEA) and ray tracing in star sensor. Specific difficulties: (a) how to evaluate thermo-optic effect in star sensor, and (b) how to make FEA results useful in optical design mode have been resolved using the scheme. Based on this scheme, the errors of star sensor, which are caused by thermo-optic effects, can be investigated in any complicated temperature condition, and the required temperature scope for the thermal design can be achieved. For example, the errors of the star sensor were 0.0863" and 2.2933", when the temperature differences of the experimental optical system were 10 °C and 5 °C in axial and lateral, respectively.Defence Science Journal, 2010, 60(3), pp.276-281, DOI:http://dx.doi.org/10.14429/dsj.60.35

Superradiant Solid in Cavity QED Coupled to a Lattice of Rydberg Gas

We study an optical cavity coupled to a lattice of Rydberg atoms, which can be represented by a generalized Dicke model. We show that the competition between the atomic interaction and atom-light coupling induces a rich phase diagram. A novel "superradiant solid" (SRS) phase is found, where both the superradiance and crystalline orders coexist. Different from the normal second order superradiance (SR) transition, here both the Solid-1/2 and SRS to SR phase transitions are first order. These results are confirmed by the large scale quantum Monte Carlo simulations.Comment: 5 pages,4 figure