Volume 113, Number 1, January 2016
|Number of page(s)||6|
|Section||Atomic, Molecular and Optical Physics|
|Published online||20 January 2016|
Bump-on-tail instability of twisted excitations in rotating cold atomic clouds
1 Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa 1049-001 Lisboa, Portugal
2 Institute für Theoretische Physik, Universität Innsbruck - 6020 Innsbruck, Austria
3 Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences 6020 Innsbruck, Austria
4 Physics of Information Group, Instituto de Telecomunicações - Lisbon, Portugal
Received: 24 November 2015
Accepted: 4 January 2016
We develop a kinetic theory for twisted density waves (phonons), carrying a finite amount of orbital angular momentum, in large magneto-optical traps, where the collective processes due to the exchange of scattered photons are considered. Explicit expressions for the dispersion relation and for the kinetic (Landau) damping are derived and contributions from the orbital angular momentum are discussed. We show that for rotating clouds, phonons carrying orbital angular momentum can cross the instability threshold and grow out of noise, while the usual plane-wave solutions are kinetically damped.
PACS: 37.10.De – Atom cooling methods / 37.10.Vz – Mechanical effects of light on atoms, molecules, and ions / 52.35.Dm – Sound waves
© EPLA, 2016
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