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arXiv · 1708.00937

Flocking from a quantum analogy: Spin-orbit coupling in an active fluid

Benjamin Loewe·Anton Souslov·Paul M. Goldbart
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Abstract

Systems composed of strongly interacting self-propelled particles can form a spontaneously flowing polar active fluid. The study of the connection between the microscopic dynamics of a single such particle and the macroscopic dynamics of the fluid can yield insights into experimentally realizable active flows, but this connection is well understood in only a few select cases. We introduce a model of self-propelled particles based on an analogy with the motion of electrons that have strong spin-orbit coupling. We find that, within our model, self-propelled particles are subject to an analog of the Heisenberg uncertainty principle that relates translational and rotational noise. Furthermore, by coarse-graining this microscopic model, we establish expressions for the coefficients of the Toner-Tu equations---the hydrodynamic equations that describe an active fluid composed of these "active spins." The connection between self-propelled particles and quantum spins may help realize exotic phases of matter using active fluids via analogies with systems composed of strongly correlated electrons.

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Benjamin Loewe, Anton Souslov, Paul M. Goldbart. 2017-08-02. Flocking from a quantum analogy: Spin-orbit coupling in an active fluid. https://doi.org/10.1088/1367-2630%2Faa9cdc

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