Physical curl forces: dipole dynamics near optical vortices

@article{Berry2013PhysicalCF,
  title={Physical curl forces: dipole dynamics near optical vortices},
  author={Michael V. Berry and Pragya Shukla},
  journal={Journal of Physics A},
  year={2013},
  volume={46},
  pages={422001}
}
The force on a particle with complex electric polarizability is known to be not derivable from a potential, so its curl is non-zero. This ‘curl force’ is studied in detail for motion near an anisotropic optical vortex of arbitrary strength. Fundamental questions are raised by the fact that although the curl force requires the polarizability to have a non-zero imaginary part, reflecting absorption or scattering (‘dissipation’) in the internal dipole dynamics, the particle motion that it… 
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