Transient Fluctuation-Induced Force

red ball Active matter? Some examples:

 

Self-propelled colloidal particles                                                            Shaken Grains            

red ball Are there long-ranged fluctuation-induced forces in active matter?

yellow ball "Fluctuation-Induced Casimir Forces in Granular Fluids,"

C. Cattuto, R. Brito, U.M.B. Marconi, F. Nori, and R. Soto, Phys. Rev. Lett. 96, 178001 (2006)

yellow ball "Nonadditivity of Fluctuation-Induced Forces in Fluidized Granular Media,"

M.R. Shaebani1, J. Sarabadani, and D.E. Wolf, Phys. Rev. Lett. 108, 198001 (2012)

yellow ball "Casimir effect in active matter systems,"

D. Ray, C. Reichhardt, and C.J. Olson Reichhardt, Phys. Rev. E 90, 013019 (2014)

yellow ballThe answer is negative: No long-ranged correlations and no long-ranged interactions in steady state.

red ball Agitating active matter from rest:

yellow ball C.M. Rohwer, M. Kardar and Matthias Krüger, Phys. Rev. Lett. 188, 015702 (2017)                

red ballFluctuations of the conserved density field satisfy (model B):

Resulting steady state is trivial

red ballWhat happens when the level of activity/noise is suddently changed (quench)?

yellow ball "Out of equilibrium behavior of Casimir-type fluctuation-induced forces for free classical fields,"

D. Dean and A. Gopinathan, Phys. Rev. E 81, 041126 (2010)

red ballTransient fluctuation-induced force between plates:

red ballTransient fluctuation-induced force between two inclusions:

Conserved density leads to transient long-ranged force. (How "universal" is this result?)