# Mainz 2017 – wissenschaftliches Programm

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# Q: Fachverband Quantenoptik und Photonik

## Q 38: Quantum Gases: Bosons V

### Q 38.4: Vortrag

### Mittwoch, 8. März 2017, 15:15–15:30, P 204

**Droplet Formation in Quantum Ferrofluids in Ring Trap Geometry** — •Antun Balaž^{1} and Axel Pelster^{2} — ^{1}Scientific Computing Laboratory, Center for the Study of Complex Systems, Institute of Physics Belgrade, University of Belgrade, Serbia — ^{2}Physics Department and Research center OPTIMAS, Technical University of Kaiserslautern, Germany

In the recent experiment [1], the Rosensweig instability was observed in a quantum ferrofluid of a strongly dipolar BEC, leading to a formation of atomic droplets. In Ref. [2] it was demonstrated that the stability of such droplets is due to quantum fluctuation correction of the ground-state energy [3,4]. Here we extend this previous theoretical description and develop a full Bogoliubov-Popov theory, which also takes into account the condensate depletion due to quantum fluctuations. We apply this approach to study the droplet formation in a ^{164}Dy BEC in ring trap geometry where, after a sudden reduction of the scattering length, the dipolar quantum gas creates a droplet ring. We use extensive numerical simulations in order to study various properties of the emerging droplets, such as their number, size, and distribution. We also study how a phase imprinting affects the droplet formation process.

[1] H. Kadau, et al., Nature **530**, 194 (2016).

[2] L. Chomaz, et al., Phys. Rev. X **6**, 041039 (2016).

[3] T. D. Lee, K. Huang, and C.N. Yang, Phys. Rev. **106**, 1135 (1957).

[4] A.R.P. Lima and A. Pelster, Phys. Rev. A **84**, 041604(R) (2011); Phys. Rev. A **86**, 063609 (2012).