Spontaneous Splitting of a Quadruply Charged Vortex

Abstract

We studied the splitting instability of a quadruply charged vortex both experimentally and theoretically. The density defect, which is a signature of the vortex core, is experimentally observed to deform into a linear shape. The deformed defect is theoretically confirmed to be an array of four linearly aligned singly charged vortices. The array of vortices rotates and precesses simultaneously with different angular velocities. The initial state of the system is not rotationally symmetric, which enables spontaneous splitting without external perturbations.

Is a Doubly Quantized Vortex Dynamically Unstable in Uniform Superfluids?

“…The realization of MQV in the BECs of ultra-cold gases sheds light on this problem, and vortex splitting has been observed. [7][8][9] The MQV in trapped systems can be dynamically unstable, and split into vortices with smaller winding numbers according to the Bogoliubovde Gennes (BdG) analysis at zero temperature. [10][11][12][13][14][15][16][17] Dynamic instability may occur when the excitation modes have complex frequencies as a result of coupling or "mixing" between two modes with positive and negative excitation energies.…”

Stabilization and Pumping of Giant Vortices in Dilute Bose–Einstein Condensates

“…(5)]. In the case of a multiquantum vortex, dynamical instability typically signifies that the vortex is unstable against splitting into singly quantized vortices [24][25][26][27][28][29][30][31].…”

“…Although this result is generally true only in an infinite homogeneous system, it still holds in finite-sized BECs for a majority of trap geometries and particle numbers. Being able to create vortices with large winding numbers would provide access to novel vortex-splitting patterns beyond the typical linear chain that prevails in the decay of two-and four-quantum vortices [25,28]. Because of the distinct nature of the different splitting patterns predicted for highly quantized vortices [30], observing the decay of such states would enable a lucid comparison between theory and experiment.…”

“…However, a serious challenge is posed by the dynamical instability of the giant vortices that becomes more pronounced as the vorticity increases [20,23]. Dynamical instabilities can lead to dissociation of the vortex even in the absence of dissipation [24][25][26][27][28][29][30][31], and therefore their effect cannot be disposed of by reducing temperature.…”

Exact Solutions to the Three-Dimensional Gross–pitaevskii Equation With Modulated Radial Nonlinearity

“…The realization of higher-dimensional matter-wave solitons is still a challengeable task because they are usually unstable for the nonlinear Schrödinger (NLS) equation with constant or uniform couplings due to the weak and strong collapses of the BECs [7]. Modulation of atomic scattering length by the Feshbach resonance is expected to dynamically stabilize higher dimensional bright solitons [18].On the other hand, a multi-quantized vortex is usually unstable when the BECs are trapped in harmonic potential [19][20][21][22][23]. It will split into several singly-quantized vortices.…”