We study the time-dependent Gross–Pitaevskii equation describing Bose–Einstein condensation of trapped dipolar quantum gases. Existence and uniqueness as well as the possible blow-up of solutions are studied. Moreover, we discuss the problem of dimension reduction for this nonlinear and nonlocal Schrödinger equation.
Ground states and dynamical properties of a dipolar Bose–Einstein condensate are analyzed based on the Gross–Pitaevskii–Poisson system (GPPS) and its dimension reduction models under an anisotropic confining potential. We begin with the three-dimensional (3D) GPPS and review its quasi-two-dimensional (2D) approximate equations when the trap is strongly confined in the z-direction and quasi-one-dimensional (1D) approximate equations when the trap is strongly confined in the x- and y-directions. In fact, in the quasi-2D equations, a fractional Poisson equation with the operator (−Δ)1/2 is involved which brings significant difficulties into the analysis. Existence and uniqueness as well as nonexistence of the ground state under different parameter regimes are established for the quasi-2D and quasi-1D equations. Well-posedness of the Cauchy problem for both types of equations and finite time blow-up in two dimensions are analyzed. Finally, we rigorously prove the convergence with linear convergence rate for the solutions of the 3D GPPS and its quasi-2D and quasi-1D approximate equations in the weak interaction regime.
This article concerns the singularly of perturbed Gross-Pitaevskii equations in trapped dipolar quantum gases, $$\displaylines{ - \varepsilon^2 \Delta u + V(x)u +{\lambda _1}{| u |^2}u + {\lambda _2}(K * {| u |^2})u= 0 \quad \text{in } \mathbb{R}^3, \cr u > 0,\quad u \in {H^1}({\mathbb{R}^3}), }$$ where ε is a small positive parameter, λ1,λ2∈R, ∗ denotes the convolution, K(x)=∣x∣31−3cos2θ and θ=θ(x) is the angle between the dipole axis determined by (0,0,1) and the vector x. Moreover, the potential V satisfies liminf∣x∣→∞V(x)>infR3V(x)=0. Under certain assumptions on (λ1,λ2)∈R2, we construct a family of positive solutions uε∈H1(R3) whose L∞ norm approaches 0 as ε→0. Our main results extend the results in Byeon and Wang [6] which dealt with singularly perturbed Schrodinger equations with a local nonlinearity, to the nonlocal Gross-Pitaevskii type equation. For more information and the latex file, see https://ejde.math.txstate.edu/Volumes/2026/48/abstr.html
The purpose of this paper is to study the dynamics of solutions to an extended Gross–Pitaevskii equation that models the formation of droplets in a dipolar Bose–Einstein condensate (BEC). The formation of these droplets has been recently discovered by driving the BEC into the strongly dipolar regime. Surprisingly, instead of collapsing, the system formed stable droplets. So far, no rigorous mathematical explanation has been proved. To the best of our knowledge, only experimental results have been obtained. The goal of this paper is to validate this breakthrough discovery. Many predictions/ conjectures properties of these droplets have been stated by some research groups in physics and engineering. In particular, it has been claimed that the stability of these droplets is a consequence of the presence of the damping term in the extended Gross–Pitaevskii equation under study. This term describes the three-body loss process. To accurately model the dynamics of formation of these droplets, it is necessary to consider a time-dependent harmonic trapping potential as well as other terms with different types of nonlinearity among them that describe the Lee–Huang–Yang (LHY). This presents some challenges that will be solved in this paper.