Non-equilibrium properties of an active nanoparticle in a harmonic potential.


Journal article


Falko Schmidt, Hana Šípová-Jungová, Mikael Käll, Alois Würger, Giovanni Volpe
Nature Communications, vol. 12(1), 2021 Feb 26, pp. 1902-1902

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APA
Schmidt, F., Šípová-Jungová, H., Käll, M., Würger, A., & Volpe, G. (2021). Non-equilibrium properties of an active nanoparticle in a harmonic potential. Nature Communications, 12(1), 1902–1902.

Chicago/Turabian
Schmidt, Falko, Hana Šípová-Jungová, Mikael Käll, Alois Würger, and Giovanni Volpe. “Non-Equilibrium Properties of an Active Nanoparticle in a Harmonic Potential.” Nature Communications 12, no. 1 (February 26, 2021): 1902–1902.

MLA
Schmidt, Falko, et al. “Non-Equilibrium Properties of an Active Nanoparticle in a Harmonic Potential.” Nature Communications, vol. 12, no. 1, Feb. 2021, pp. 1902–02.


Abstract:
Active particles break out of thermodynamic equilibrium thanks to their directed motion, which leads to complex and interesting behaviors in the presence of confining potentials. When dealing with active nanoparticles, however, the overwhelming presence of rotational diffusion hinders directed motion, leading to an increase of their effective temperature, but otherwise masking the effects of self-propulsion. Here, we demonstrate an experimental system where an active nanoparticle immersed in a critical solution and held in an optical harmonic potential features far-from-equilibrium behavior beyond an increase of its effective temperature. When increasing the laser power, we observe a cross-over from a Boltzmann distribution to a non-equilibrium state, where the particle performs fast orbital rotations about the beam axis. These findings are rationalized by solving the Fokker-Planck equation for the particle’s position and orientation in terms of a moment expansion. The proposed self-propulsion mechanism results from the particle’s non-sphericity and the lower critical point of the solution.
A nanosphere is being trapped near the surface of a cover glass by an optical tweezers. As part of the light is being absorbed by the particle a contraction gradient in its vicinity is induced that propels it away from the trapping center.

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