BEC FLOW · Instability of superfluid flow in dilute Bose-Einstein condensates
FP6 — Marie Curie Actions (Human Resources and Mobility)
- Duration
- 2004-09-01 → 2006-08-31
- EU contribution
- €159,353
- Participants
- 1
- Scheme
- IIF
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Results in brief
Final Activity Report Summary - BEC FLOW (Instability of superfluid flow in dilute Bose-Einstein condensates)
We have demonstrated the existence of a drag force due to quantum fluctuations in a superfluid. This has many important consequences. In particular, it brings us a step closer towards developing a feasible theory to explain observed instability in superfluids, an issue that scientists have been wrestling with since the 1940s. Showing that quantum fluctuations have such a drag effect also has direct bearing on the conception and design of applications, such as the atom laser, where precision in predicting superfluid behaviour is vital. We also explored the mixtures of superfluids, which current experiments are beginning to explore.
Data: CORDIS, © European Union
Project objective
We propose to investigate the instability of superfluid flow in a dilute Bose-Einstein condensate with repulsive interactions. Landau proposed that the primary mechanism for superfluid flow instability is the excitation of quasiparticles.While this is t he traditionally accepted explanation, the critical velocity, i.e. the velocity at which the superfluid flow becomes unstable, that Landau predicted based on quasiparticle excitation is generally known to be significantly higher than the experimentally ascertained critical velocity. Preliminary calculations show that using the breakdown of thermodynamic equilibrium as the primary mechanism for instability leads to a theorized critical velocity that is much lower than the Landau critical velocity.We thus plan to tackle the problem of superfluid flow instability by developing a kinetic theory consistent with the new critical velocity arising from the breakdown of the thermodynamic equilibrium, using this kinetic theory to develop a new two-fluid model, numerically simulating this model, and working closely with experimenters to verify our results.
Original text from CORDIS.
Participants
- CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE · PARISCoordinatorFrance
Links
Data: CORDIS, © European Union