The Theory and Practice of Fluctuation-Induced Interactions

Coordinators: Thorsten Emig, Mehran Kardar, V. Adrian Parsegian, Roya Zandi

Particle physicists need to deal with the complexity of the quantum vacuum, and typically compute interactions with tools such as Feynman diagrams or scattering theory. Atomic physicists must deal with van der Waals and London interactions due to dipolar fluctuations using perturbation theory on atomic orbitals. At larger scales the constrained quantum fluctuations of the electromagnetic field in cavities lead to Casimir and Casimir-Polder interactions. In the macroscopic realm, thermal fluctuations are important for `soft' matter. Fluctuations in superfluid films and binary mixtures are studied by methods from critical phenomena. Colloid chemists deal with entropic interactions due to simple excluded volume for neutral particles, and from the free energies of counter-ions for charged particles. The softness of biological matter makes it susceptible to such entropic interactions, as well as to consequences of non--equilibrium fluctuations. The latter are, for example, essential to the function of Brownian motors in cells. Despite their apparent diversity, the above phenomena share many conceptual and computational links.

The goal of this program is to illuminate, explore, and develop these connections in order to obtain a more coherent and comprehensive picture of fluctuation--induced interactions.

Central categories to be covered by the program include

  1. Fluctuating soft matter
  2. Shapes and geometry
  3. Quantum liquids and condensates
  4. Measurements and devices in the micro- and nano-scale