Hannover 2003 – wissenschaftliches Programm
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Q: Quantenoptik
Q 54: Fallen und Kühlung 3
Q 54.5: Vortrag
Freitag, 28. März 2003, 15:00–15:15, E001
Quantum description of stochastic cooling of trapped atoms — •Denis Ivanov1, Sascha Wallentowitz1, and Ian Walmsley2 — 1Fachbereich Physik, Universität Rostock, Rostock — 2Clarendon Laboratory, University of Oxford, Oxford, UK
Using a quantum-field approach [1] the quantum limits of stochastic cooling of trapped atoms [2] are established. One restriction is caused by the back-action noise due to the use of a measurement in the operation of stochastic cooling. This noise leads to heating of kinetic and potential energy of each atom. It can be minimized to the Heisenberg limit by the choice of the measurement resolution. The other restriction is due to fluctuations of the atom number of the ensemble, and leads to a heating effect of the whole atomic cloud. These fluctuations have to be taken into account, since the atom number is not measured and thus in principle is unknown. Moreover, atom-number fluctuations become substantially large at the condensation temperature of bosonic atoms, which can turn the sought cooling into a heating effect. Nevertheless, we show that stochastic cooling can in principle be used to reach condensation by subtle alignment of the external control fields. The speed of cooling is studied in the context of a worst-case scenario, which shows the feasibility of the method.
[1] S. Wallentowitz, Phys. Rev. A 66, 032114 (2002).
[2] M.G. Raizen et al., Phys. Rev. A 58, 4757 (1998).