Kármán vortex street in a two-component Bose–Einstein condensate

Abstract

Vortex shedding from a moving obstacle potential in a two-component Bose-Einstein condensate is investigated numerically. For a miscible two-component condensate composed of 23 Na and 87 Rb atoms, in the wake of obstacle, the Kármán vortex street is discovered in one component, while the Kármán-like vortex street named 'half-quantum vortex street' is formed in another component. The other patterns of vortex shedding, such as the vortex dipoles, V-shaped vortex pairs and corresponding 'half-quantum vortex shedding', can also be found. The drag force acting on obstacle potential is calculated and discussed. The parameter region for various vortex patterns and critical velocity for vortex emission are presented. In addition, a 85 Rb-87 Rb mixture is also considered, where the Kármán vortex street and other typical patterns exist in both components. Finally, we provide an experimental protocol for the above realization and observation.

Spin and mass currents near a moving magnetic obstacle in a two-component Bose-Einstein condensate

“…When the obstacle's velocity exceeds a critical velocity, the magnetic obstacle will emit magnons, which can be detected as a sudden enhancement in spin fluctuations in the sample. When u is increased further, another critical phenomonon involving the generation of topological objects, such as half-quantum vortices and magnetic solitons, may occur [18,19]. We also notice that another velocity point larger than u c exists, above which the obtacle center becomes fully polarized.…”

“…Spin superfluidity was demonstrated with the absence of damping in spin dipole oscillations in trapped samples [11,12], and novel topological objects such as half-quantum vortices [10,13] and magnetic solitons [14,15] were observed. These developments lead us to anticipate a moving obstacle experiment with the binary superfluid system, discussed in previous numerical studies [16][17][18][19]. In particular, the optical obstacle can be engineered to be magnetic, i.e., exhibiting different * yishin@snu.ac.kr potentials for the two spin components so that the system's properties in both the spin and the mass sectors may be addressed in a controlled manner.…”

Soliton sheets of Bose–Einstein condensates in optical lattices

“…Macroscopic excitations play an essential role in many areas of physics, particularly in Bose-Einstein condensates (BECs), which exhibit phenomena such as solitons [1][2][3][4][5][6][7][8][9], quantized vortices [10][11][12][13][14][15][16][17], vortex sheets [18][19][20][21][22][23][24], domain walls [25,26], textures [27][28][29]. These excitations are crucial for understanding the phase, superfluidity and magnetic properties of condensates.…”

Vortex Solutions in a Binary Immiscible Bose-Einstein Condensate

“…Since their initial realisation [2], vortices have been studied in two-component condensates both experimentally [5,47] and theoretically [48][49][50][51][52][53][54][55][56][57][58][59]. More recently, theoretical work has concentrated on the relaxation of a turbulent two-component BEC [60,61], dynamics of vortices in a two-component BEC [62][63][64][65], and the importance of the cross-over between the miscible and immiscible regimes [66,67].…”