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Colloquium Fabian Maucher: Pattern-formation of chemical and quantum waves

February 19, 2021 @ 3:00 pm - 4:30 pm


The emergence of spatial patterns in nature [1] continues to intrigue scientists from a broad range of natural sciences.
In this talk two of such pattern-forming dynamical systems will be presented.

The first part of this talk will focus on organising centers of three-dimensional excitable waves [4] and three-dimensional pattern formation. There are a range of chemical, physical and biological excitable media that support spiral wave vortices. Examples include the Belousov-Zhabotinsky (BZ) redox reaction, the chemotaxis of slime mould and action potentials in cardiac tissue. Usually interacting vortex strings are prone to reconnection and untying.
However, in excitable media such vortex strings can display remarkable topology preservation [5]. After presenting examples for their dynamics and their possible extraordinary robustness of topology [Fig.1 (f)] I will show recent theoretical and experimental results [6] that exploit targeted optical protocols to realise vortex or scroll rings threaded by two counter-rotating filaments in the BZ reaction and discuss their dynamics [Fig. (g-i)]. The second part will present recent results on pattern-formation in laser-cooled ultracold dipolar quantum gases. In this system the possibility of obtaining quantum states with self-organized long-ranged ordering can be facilitated b quantum fluctuations which can suppress collapse and thereby pave the way for supersolids in this system [2]. Here, supersolidity refers to a state of matter which displays long-range ordering whilst maintaining a large superfluid frac-
tion. I will present recent results which focus on the critical behaviour of the superfluid-supersolid phase-transition [3] and the crucial role quantum fluctuations can play for the latter. We find that quantum fluctuations can alter the order of the phase transition from first- to second order. Furthermore, apart from the usual triangular lattice of
density droplets, quantum fluctuations can give rise to a novel quantum state whose density distribution displays a honeycomb structure [see Fig.1(a-e)].
In a final part I will summarize current research endeavours.

[1] A. M. Turing, Philos. Trans. Royal Soc. B 23 237 (1952).
[2] H. Kadau, M. Schmitt, M. Wenzel, C. Wink, T. Maier, I. Ferrier-Barbut, T. Pfau, Nature 530 194 (2016).
[3] Y.-C. Zhang, F.M. and T. Pohl, Phys. Rev. Lett. 123, 015301 (2019).
[4] A. T. Winfree and S. H. Strogatz, Nature 311, 611 (1984)
[5] F.M. and P. Sutcliffe Phys. Rev. Lett. 116, 178101 (2016)
[6] A. Cincotti, F.M., D. Evans, B. M. Chapin, K. Horner, E. Bromley, A. Lobb, J. W. Steed, and P. Sutcliffe. Phys. Rev.
Lett. 123, 258102 (2019).

link: https://eu.bbcollab.com/guest/255f34c83a284c93bb9dee4f0115526b


February 19, 2021
3:00 pm - 4:30 pm