Related Experiment Video
Updated: Jun 25, 2026

Spectral and Angle-Resolved Magneto-Optical Characterization of Photonic Nanostructures
Published on: November 21, 2019
Momentum Exchange between Light and a Single Atom: Abraham or Minkowski?
1Centre for Cold Matter, Imperial College, Prince Consort Road, London SW7 2AZ, United Kingdom.
Abstract:
We consider forces on an atom due to a plane-wave light pulse. The standard view of the optical dipole force indicates that red-detuned light should attract the atom towards high intensity. While the atom is inside the pulse, this would increase the average momentum per photon from p_{0} to p_{0}n, where n is the average refractive index due to the presence of the atom. We show, however, that this is the wrong conclusion and that the dispersive forces repel the atom from the light in this particular case, giving the photons a momentum p_{0}/n. This leads us to identify Abraham's optical momentum with the kinetic momentum transfer. The form due to Minkowski is similarly associated with the canonical momentum. We consider the possibility of demonstrating this in the laboratory, and we note an unexpected connection with the Aharonov-Casher effect.
Related Concept Videos
The Bohr Model
The de Broglie Wavelength
Momentum And Radiation Pressure
The Quantum-Mechanical Model of an Atom
The Wave Nature of Light
Thomson's e/m Experiment
A particle with charge q, speed v, and mass m enters an area from the top, where the magnetic and electric fields are perpendicular both to the particle's motion and to one another. The magnetic...

