arXiv subjects

Nguyen Van Thu

Publications and source records attributed to Nguyen Van Thu.

21 records · Page 2Linked to original sources

arXiv2016

Casimir force of two-component Bose-Einstein condensates confined by a parallel plate geometry

Using field theory we calculate the Casimir energy and Casimir force of two-component Bose-Einstein condensates restricted between two parallel plates, in which Dirichlet and periodic boundary conditions applied. Our results show that, in one-loop approximation, the Casimir force equals to summation of the one of each component and it is vanishing in some cases: (i) inter-distance between two plates becomes large enough; (ii) intraspecies interaction is zero; (iii) interspecies interaction is full strong segregation.

cond-mat.quant-gas↗

arXiv2015

Interfacial tension and wall energy of a Bose-Einstein condensate binary mixture: triple-parabola approximation

Accurate and useful analytic approximations are developed for order parameter profiles and interfacial tensions of phase-separated binary mixtures of Bose-Einstein condensates. The pure condensates 1 and 2, each of which contains a particular species of atoms, feature healing lengths $ξ_1$ and $ξ_2$. The inter-atomic interactions are repulsive. In particular, the effective inter-species repulsive interaction strength is $K$. A triple-parabola approximation (TPA) is proposed, to represent closely the energy density featured in Gross-Pitaevskii (GP) theory. This TPA allows us to define a model, which is a handy alternative to the full GP theory, while still possessing a simple analytic solution. The TPA offers a significant improvement over the recently introduced double-parabola approximation (DPA). In particular, a more accurate amplitude for the wall energy (of a single condensate) is derived and, importantly, a more correct expression for the interfacial tension (of two condensates) is obtained, which describes better its dependence on $K$ in the strong segregation regime, while also the interface profiles undergo a qualitative improvement.

cond-mat.stat-mech↗

arXiv2015

Static interfacial properties of Bose-Einstein condensate mixtures

Interfacial profiles and interfacial tensions of phase-separated binary mixtures of Bose-Einstein condensates are studied theoretically. The two condensates are characterized by their respective healing lengths $ξ_1$ and $ξ_2$ and by the inter-species repulsive interaction $K$. An exact solution to the Gross-Pitaevskii (GP) equations is obtained for the special case $ξ_2/ξ_1 = 1/2$ and $K = 3/2$. Furthermore, applying a double-parabola approximation (DPA) to the energy density featured in GP theory allows us to define a DPA model, which is much simpler to handle than GP theory but nevertheless still captures the main physics. In particular, a compact analytic expression for the interfacial tension is derived that is useful for all $ξ_1, ξ_2$ and $K$. An application to wetting phenomena is presented for condensates adsorbed at an optical wall. The wetting phase boundary obtained within the DPA model nearly coincides with the exact one in GP theory.

cond-mat.stat-mech↗