Thermal suppression of phase separation in condensate mixtures

We examine the role of thermal fluctuations in binary condensate mixtures of dilute atomic gases. In particular, we use Hartree-Fock-Bogoliubov with Popov approximation to probe the impact of non-condensate atoms to the phenomenon of phase-separation in two-component Bose-Einstein condensates. We demonstrate that, in comparison to $T=0$, there is a suppression in the phase-separation of the binary condensates at $T\neq0$. This arises from the interaction of the condensate atoms with the thermal cloud. We also show that, when $T\neq0$ it is possible to distinguish the phase-separated case from miscible from the trends in the correlation function. However, this is not the case at $T=0$.Comment: 5 pages, 4 figure

Evolution of Goldstone mode in binary condensate mixtures

We show that the third Goldstone mode in the two-species condensate mixtures, which emerges at phase-separation, gets hardened when the confining potentials have separated trap centers. The {\em sandwich} type condensate density profiles, in this case, acquire a {\em side-by-side} density profile configuration. We use Hartree-Fock-Bogoliubov theory with Popov approximation to examine the mode evolution and density profiles for these phase transitions at $T=0$.Comment: 5 pages, 2 figures. Some part of the theory is common to arXiv:1307.5716 and arXiv:1405:6459, so that the article is self-contained for the benefit of the reader

Ramifications of topology and thermal fluctuations in quasi-2D condensates

We explore the topological transformation of quasi-2D Bose-Einstein condensates of dilute atomic gases, and changes in the low-energy quasiparticles associated with the geometry of the confining potential. In particular, we show the density profile of the condensate and quantum fluctuation follow the transition from a multiply to a simply connected geometry of the confining potential. The thermal fluctuations, in contrast, remain multiply connected. The genesis of the key difference lies in the structure of the low-energy quasiparticles. For which we use the Hartree-Fock-Bogoliubov, and study the evolution of quasiparticles, the dipole or the Kohn mode in particular. We, then employ the Hartree-Fock-Bogoliubov theory with the Popov approximation to investigate the density and the momentum distribution of the thermal atoms.Comment: 7 pages, 8 figure

Position swapping and pinching in Bose-Fermi mixtures with two-color optical Feshbach resonances

We examine the density profiles of the quantum degenerate Bose-Fermi mixture of $^{174}$Yb-$^{173}$Yb, experimental observed recently, in the mean field regime. In this mixture there is a possibility of tuning the Bose-Bose and Bose-Fermi interactions simultaneously using two well separated optical Feshbach resonances, and it is a good candidate to explore phase separation in Bose-Fermi mixtures. Depending on the Bose-Bose scattering length a_\BB, as the Bose-Fermi interaction is tuned the density of the fermions is pinched or swapping with bosons occurs.Comment: 8 pages, 7 figure

Electric dipole polarizabilities of alkali metal ions from perturbed relativistic coupled-cluster theory

We use the perturbed relativistic coupled-cluster theory to compute the static electric dipole polarizabilities of the singly ionized alkali atoms, namely, Na$^+$, $^+$, Rb$^+$, Cs$^+$ and Fr$^+$. The computations use the Dirac-Coulomb-Breit Hamiltonian with the no-virual-pair approximation and we also estimate the correction to the static electric dipole polarizability arising from the Breit interaction.Comment: 8 pages, 3 figures and 9 tables. arXiv admin note: text overlap with arXiv:1210.547

Critical Temperature for Bose-Einstein condensation in quartic potentials

The quartic confining potential has emerged as a key ingredient to obtain fast rotating vortices in BEC as well as observation of quantum phase transitions in optical lattices. We calculate the critical temperature $T_c$ of bosons at which normal to BEC transition occurs for the quartic confining potential. Further more, we evaluate the effect of finite particle number on $T_c$ and find that $\Delta T_c/T_c$ is larger in quartic potential as compared to quadratic potential for number of particles $< 10^5$. Interestingly, the situation is reversed if the number of particles is $\gtrsim10^5$.Comment: 2 figures, 5 pages, accepted for publication in Euro. Phys. J.