Abstract
Vortices are essential to angular momentum in quantum systems such as ultracold atomic gases. The existence of quantized vorticity in bosonic systems stimulated the development of the Gross-Pitaevskii mean-field approximation. However, the true dynamics of angular momentum in finite, interacting many-body systems like trapped Bose-Einstein condensates is enriched by the emergence of quantum correlations whose description demands more elaborate methods. Herein we theoretically investigate the full many-body dynamics of the acquisition of angular momentum by a gas of ultracold bosons in two dimensions using a standard rotation procedure. We demonstrate the existence of a novel mode of quantized vorticity, which we term the phantom vortex. Contrary to the conventional mean-field vortex, can be detected as a topological defect of spatial coherence, but not of the density. We describe previously unknown many-body mechanisms of vortex nucleation and show that angular momentum is hidden in phantom vortices modes which so far seem to have evaded experimental detection. This phenomenon is likely important in the formation of the Abrikosov lattice and the onset of turbulence in superfluids.
Highlights
To cite this version: Storm Weiner, Marios Tsatsos, Lorenz Cederbaum, Axel Lode
We describe previously unknown many-body mechanisms of vortex nucleation and show that angular momentum is hidden in phantom vortices modes which so far seem to have evaded experimental detection
Our results demonstrate that angular momentum in fragmented condensates manifests itself in a new type of coreless vortex, which we name the phantom vortex due to its elusive nature
Summary
In silico, by first computing the many-body ground state of interacting bosons in an isotropic harmonic trap. (d) Comparison of energy and angular momentum curves for M = 4 (solid lines) and M = 1 (GP, dotted lines) Both quantities agree between the two cases until around t = 80 when fragmentation becomes significant and the GP ansatz breaks down. A state is considered coherent when only one natural orbital has significant occupation In this case, the full information of the many-body wavefunction is contained in a single one-particle state and the Gross-Pitaevskii mean-field approximation is valid. From the view of the RDM, the MCTDHB approach generalizes the mean-field approximation by allowing a dynamical transition from coherence to fragmentation. This means that, contrary to the mean-field case, the natural occupations are allowed to have non-integer values and vary in time.
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