title: Non-Boltzmann stationary distributions and nonequilibrium relations in active baths.
abstract: Most natural and engineered processes, such as biomolecular reactions, protein folding, and population dynamics, occur far from equilibrium and therefore cannot be treated within the framework of classical equilibrium thermodynamics. Here we experimentally study how some fundamental thermodynamic quantities and relations are affected by the presence of the nonequilibrium fluctuations associated with an active bath. We show in particular that, as the confinement of the particle increases, the stationary probability distribution of a Brownian particle confined within a harmonic potential becomes non-Boltzmann, featuring a transition from a Gaussian distribution to a heavy-tailed distribution. Because of this, nonequilibrium relations (e.g., the Jarzynski equality and Crooks fluctuation theorem) cannot be applied. We show that these relations can be restored by using the effective potential associated with the stationary probability distribution. We corroborate our experimental findings with theoretical arguments.
authors.affiliation: Department of Physics, University of Gothenburg, SE-41296 Gothenburg, Sweden.|Soft Matter Lab, Department of Physics, Bilkent University, Cankaya, 06800 Ankara, Turkey.
authors.forename: Aykut
authors.initials: A
authors.lastname: Argun
authors.affiliation: Soft Matter Lab, Department of Physics, Bilkent University, Cankaya, 06800 Ankara, Turkey.|Department of Physics, University of Zanjan, P.O. Box 45195-313, Zanjan, Iran.|Optics Research Center, Institute for Advanced Studies in Basic Sciences, P.O. Box 45137-66731, Zanjan, Iran.
authors.forename: Ali-Reza
authors.initials: AR
authors.lastname: Moradi
authors.affiliation: Soft Matter Lab, Department of Physics, Bilkent University, Cankaya, 06800 Ankara, Turkey.
authors.forename: Erçaǧ
authors.initials: E
authors.lastname: Pinçe
authors.affiliation: Department of Materials Science and Nanotechnology Engineering, TOBB University of Economics and Technology, 06560 Ankara, Turkey.
authors.forename: Gokhan Baris
authors.initials: GB
authors.lastname: Bagci
authors.affiliation: Department of Physics and Astronomy, University of Aarhus Ny Munkegade, Building 1520, DK-8000 Aarhus C, Denmark.
authors.forename: Alberto
authors.initials: A
authors.lastname: Imparato
authors.affiliation: Department of Physics, University of Gothenburg, SE-41296 Gothenburg, Sweden.|Soft Matter Lab, Department of Physics, Bilkent University, Cankaya, 06800 Ankara, Turkey.|UNAM-National Nanotechnology Research Center, Bilkent University, Ankara 06800, Turkey.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Volpe