Effect of an oscillating Gaussian obstacle in a dipolar Bose-Einstein condensate

Abstract

We study the dynamics of vortex dipoles in erbium ( 168 Er) and dysprosium ( 164 Dy) dipolar Bose-Einstein condensates (BECs) by applying an oscillating blue-detuned laser (Gaussian obstacle). For observing vortex dipoles, we solve a nonlocal Gross-Pitaevskii (GP) equation in quasi two-dimensions in real-time. We calculate the critical velocity for the nucleation of vortex dipoles in dipolar BECs with respect to dipolar interaction strengths. We also show the dynamics of the group of vortex dipoles and rarefaction pulses in dipolar BECs. In the dipolar BECs with Gaussian obstacle, we observe rarefaction pulses due to interaction of dynamically migrating vortex dipoles. PACS. 67.25.dk Vortices and turbulence -67.85.De Dynamic properties of condensates; excitations, and superfluid flow -03.75.-b Matter waves -47.37.+q Hydrodynamic aspects of superfluidity; quantum fluids arXiv:1809.07634v1 [cond-mat.quant-gas]

Characterization of the energy level-structure of a trapped dipolar Bose gas via mean-field parametric resonances

“…A and δA are in units of hω, β in a −2 ho , and Ω is in units of ω. As already noted in the introduction, the analog of the present excitation method is the periodic modulation of a scattering length such as a(t) = a bg + δa sin(ωt) [19][20][21], where δa is the modulation amplitude, and a bg an unperturbed background. The analog of a bg is the A and of δa the δA.…”

“…The phenomenon of parametric resonances (PRs) is ubiquitious in nature and is a widely examined fundamental physical property. Today, PRs are one of the outstanding features observed in Bose-Einstein condensates (BECs) [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] where resonances are usually the result of modulating one of the system parameters such as the scattering length [11,[19][20][21][22]. They are also generated by external means such as a time-dependent trapping geometry [11], laser stirring [2], and laser-intensity modulation [1].…”

“…Another goal is to reveal the interplay between trapping geometry and DDI (cf. [20,[33][34][35]) in defining the frequencies at which PRs occur. Effects of trapping geometry have already been studied earlier such as the influence of the trap aspect ratio on the oscillation frequencies [36] and stability of a DBEC [37,38], except that it hasn't been related to the structure of the trap energy levels.…”

Interplay between binary and three-body interactions and enhancement of stability in trapless dipolar Bose-Einstein condensates

“…The advent of Bose-Einstein condensates (BECs) in 52 Cr [1,2], 164 Dy [3,4] and 168 Er [5] accompanied by long-range dipole-dipole (DD) interactions superimposed on the contact interatomic collisions has impacted the investigation of ultracold quantum gases [6]. The anisotropic character and long-range nature of DD interactions endows the dipolar BECs (DBECs) with several distinct features such as the subordination of stability on the trap geometry [1,2], rotonmaxon character of the excitation spectrum [7,8], new dispersion relations for elementary excitations [9,10], novel quantum phases [11,12], explicit [13,14] and hidden vortices [15], specific vortex-antivortex pairs [16], anisotropic multidimensional solitons [17,18], quantum droplets stabilized by beyond-mean-field effects [19,20,21], etc. The above phenomena arise due to the interplay between the contact s-wave interactions and the dipolar attraction or repulsion [22].…”

Stabilization of trapless dipolar Bose-Einstein condensates by temporal modulation of the contact interaction

“…After the experimental realization of Bose-Einstein condensates (BECs) of 52 Cr [1,2], 164 Dy [3,4] and 168 Er [5] with long-range dipole-dipole (DD) interaction superposed on the short-range atomic interaction marks a major development in ultra cold quantum gases. Because of the long-range nature and anisotropic character of the DD interaction, the dipolar BEC possesses many distinct features and new exciting phenomena such as the dependence of stability on the trap geometry [1,2], new dispersion relations of elementary excitations [6][7][8], unusual equilibrium shapes, roton-maxon character of the excitation spectrum [8][9][10][11][12][13], novel quantum phases including supersolid and checkerboard phases [14][15][16], vortices [17,18], hidden vortices [19], dynamics of vortexantivortex pairs [20] etc. These features arise due to the interplay between the s-wave contact interaction and the dipolar interaction.…”