Static interfacial properties of Bose-Einstein-condensate mixtures

Abstract

The 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 and £2 and by the interspecies repulsive interaction K. An exact solution to the Gross-Pitaevskii (GP) equations is obtained for the special case I 2/ I 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 f ,, | 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.

On the finite-size effects in two segregated Bose-Einstein condensates restricted by a hard wall

“…Moreover, the Dirichlet BC is also consistent with the condition in the infinite space ψ 1 ( ì a, −∞) = 0 [16,18]. As to the second condensate, we have two options: either…”

“…It is convenient to write all quantities in the dimensionless forms by introducing new quantities = z/ξ 1 , h = h /ξ 1 , = L/ξ 1 and φ j = ψ j / √ n j , where the densities n j ( j = 1, 2) were determined in [16]. In the dimensionless forms, the GP Hamiltonian (2.1) is rewritten as follows:…”

“…To this end, we make use of the double-parabola approximation (DPA) method which was proposed in [14,15] and was developed in [16][17][18]. The boundary problem we deal with is schematically given in figure 1 where the hard wall (optical wall) is placed at z = −h , the interface at z = L and the curve j ( j = 1, 2) represent the condensate profile φ j (z) which will be introduced in the next section.…”

Casimir Force of Two-Component Bose–Einstein Condensates Confined by a Parallel Plate Geometry

“…To our understanding, the study of the Casimir force in two-component Bose-Einstein condensates (BECs) is so far still absent although many aspects have been researched, for example, statics properties [13][14][15], dynamical excitations [16,17], etc. The goal of this paper is to remedy this gap.…”

Ripplon Modes of Two Segregated Bose-Einstein Condensates in Confined Geometry

“…The phase separation in binary mixtures of Bose-Einstein condensates was theoretically predicted [1,2] and observed later in experiments [3][4][5][6][7][8]. Since then many works have been devoted to explore the statics, the dynamics and the ripplon modes of two segregated BECs [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. However, most of them concerned with the systems in infinite space, while all experimental realizations have been carried out in restricted regions of space with spatial structure being more and more complicated.…”