Feasibility of Experimental Realization of Entangled Bose-Einstein Condensation

We examine the practical feasibility of the experimental realization of the so-called entangled Bose-Einstein condensation (BEC), occurring in an entangled state of two atoms of different species. We demonstrate that if the energy gap remains vanishing, the entangled BEC persists as the ground state of the concerned model in a wide parameter regime. We establish the experimental accessibility of the isotropic point of the effective parameters, in which the entangled BEC is the exact ground state, as well as the consistency with the generalized Gross-Pitaevskii equations. The transition temperature is estimated. Possible experimental implementations are discussed in detail.Comment: 6 pages, published versio

BCS-Bose Crossover in Color Superconductivity

It is shown that the onset of the color superconducting phase occurs in the BCS-BE crossover region.Comment: 5 pages, LaTeX, references adde

A proposal of an orbital-dependent correlation energy functional for energy-band calculations

An explicitly orbital-dependent correlation energy functional is proposed, which is to be used in combination with the orbital-dependent exchange energy functional in energy-band calculations. It bears a close resemblance to the second-order direct and exchange perturbation terms calculated with Kohn-Sham orbitals and Kohn-Sham energies except that one of the two Coulomb interactions entering each term is replaced by an effective interaction which contains information about long-, intermediate-, and short-range correlations beyond second-order perturbation theory. Such an effective interaction can rigorously be defined for the correlation energy of the uniform electron liquid and is evaluated with high accuracy in order to apply to the orbital-dependent correlation energy functional. The coupling-constant-averaged spin-parallel and spin-antiparallel pair correlation functions are also evaluated with high accuracy for the electron liquid. The present orbital-dependent correlation energy functional with the effective interaction borrowed from the electron liquid is valid for tightly-binding electrons as well as for nearly-free electrons in marked contrast with the conventional local density approximation.Comment: 32 pages, 11 figures, and 1 tabl

On massive photons inside a superconductor as follows from London and Ginzburg-Landau theory

A phenomenological derivation in the frame of London's and Ginzburg-Landau theories is given that photons behave inside a superconductor as if they have mass