Erlangen 2018 – scientific programme
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A: Fachverband Atomphysik
A 35: Ultracold Atoms I (joint session Q/A)
A 35.6: Talk
Thursday, March 8, 2018, 11:45–12:00, K 1.022
Dissipative cooling of quasi-condensate excitations — •Carsten Henkel1 and Isabelle Bouchoule2 — 1Universität Potsdam — 2Institut d'Optique, Palaiseau
The elementary excitations of a Bose condensate are described by the celebrated Bogoliubov dispersion. Their spectrum is discrete for a trapped system. We discuss the theory of these excitations in experiments where atoms leave the trap in a controlled way. One observes a stationary non-equilibrium situation where temperature measurements give different results, either from the density profile or from density fluctuations [1]. We develop a simple stochastic theory based on quantum projection noise and find that the limiting temperature is slightly below the chemical potential. The calculations need accurate Bogoliubov mode functions that interpolate smoothly between the dense (Thomas-Fermi) region and the low-density wings [2, 3], a region where mean-field theories fail [4, 5].
[1] A. Johnson, S. Szigeti, M. Schemmer, and I. Bouchoule, Phys. Rev. A 96 (2017) 013623
[2] A. L. Fetter and D. L. Feder, Phys. Rev. A 58 (1998) 3185
[3] A. Diallo and C. Henkel, J. Phys. B 48 (2015) 165302
[4] L. Pitaevskii and S. Stringari, Phys. Rev. Lett. 81 (1998) 4541
[5] C. Henkel, T.-O. Sauer, and N. P. Proukakis, J. Phys. B 50 (2017) 114002