Trace Expressions and Associated Limits for Non-Equilibrium Casimir Torque
arXiv:2207.13646 · doi:10.1103/PhysRevA.106.042222
Abstract
We exploit fluctuational electrodynamics to present trace expressions for the torque experienced by arbitrary objects in a passive, non-absorbing, rotationally invariant background environment. Specializing to a single object, this formalism, together with recently developed techniques for calculating bounds via Lagrange duality, is then used to derive limits on the maximum Casimir torque that a single object with an isotropic electric susceptibility can experience when out of equilibrium with its surrounding environment. The maximum torque achievable at any wavelength is shown to scale in proportion to body volumes in both subwavelength (quasistatics) and macroscopic (ray optics) settings, and come within an order of magnitude of achievable torques on topology optimized bodies. Finally, we discuss how to extend the formalism to multiple bodies, deriving expressions for the torque experienced by two subwavelength particles in proximity to one another.
References in corpus (7)
- Casimir-Lifshitz force out of thermal equilibrium
- Casimir-Lifshitz force out of thermal equilibrium and asymptotic non-additivity
- Total Angular Momentum Waves for Scalar, Vector, and Tensor Fields
- Casimir-Lifshitz force out of thermal equilibrium between dielectric gratings
- On the Computation of Power in Volume Integral Equation Formulations
- Heuristic Methods and Performance Bounds for Photonic Design
- Casimir forces between cylinders at different temperatures