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Do waves carrying orbital angular momentum possess azimuthal linear momentum?
Fiona C Speirits1, Stephen M Barnett1
1Department of Physics, University of Strathclyde, Glasgow G4 0NG, United Kingdom.
Physical Review Letters
|August 29, 2014
Summary
Vortex beams carry orbital angular momentum. This study resolves the paradox of their apparent azimuthal linear momentum by demonstrating it
Area of Science:
- Optics
- Quantum Mechanics
- Photonics
Background:
- Beams are typically superpositions of plane waves with linear momentum along their propagation direction.
- Plane waves lack a net azimuthal momentum component.
- Holographic interactions can generate vortex beams with orbital angular momentum.
Purpose of the Study:
- To resolve the apparent paradox of azimuthal linear momentum in vortex beams.
- To clarify the nature of momentum in beams generated by holographic processes.
Main Methods:
- Theoretical analysis of plane wave superposition.
- Investigation of momentum transfer during holographic beam generation.
- Decomposition of linear momentum density.
Main Results:
- Vortex beams possess orbital angular momentum.
- The perceived azimuthal linear momentum is not a true linear momentum.
- Azimuthal momentum density is a valid component of the linear momentum density.
Conclusions:
- The paradox of azimuthal momentum in vortex beams is resolved.
- Momentum in optical beams is more complex than simple plane wave propagation.
- Understanding momentum density is crucial for holographic beam manipulation.
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