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Article: Atom loss maximum in ultra-cold Fermi gases

TitleAtom loss maximum in ultra-cold Fermi gases
Authors
Issue Date2011
PublisherInstitute of Physics Publishing Ltd. The Journal's web site is located at http://www.iop.org/EJ/journal/NJP
Citation
New Journal Of Physics, 2011, v. 13 How to Cite?
AbstractRecent experiments on atom loss in ultra-cold Fermi gases all show a maximum at a magnetic field below Feshbach resonance, where the s-wave scattering length is large (comparable to inter-particle distance) and positive. These experiments have been performed over a wide range of conditions, with temperatures and trap depths spanning three decades. Different groups have come up with different explanations, including the emergence of Stoner ferromagnetism. Here, we show that this maximum is a consequence of two major steps. The first is the establishment of a population of shallow dimers, which is the combined effect of dimer formation through three-body recombination, and the dissociation of shallow dimers back to atoms through collisions. The dissociation process will be temperature dependent and is affected by Pauli blocking at low temperatures. The second is the relaxation of shallow dimers into tightly bound dimers through atom-dimer and dimer-dimer collisions. In these collisions, a significant amount of energy is released. The reaction products leave the trap, leading to trap loss. We have constructed a simple set of rate equations describing these processes. Remarkably, even with only a few parameters, these equations reproduce the loss rate observed in all recent experiments, despite their widely different experimental conditions. Our studies show that the location of the maximum loss rate depends crucially on experimental parameters such as trap depth and temperature. These extrinsic characters show that this maximum is not a reliable probe of the nature of the underlying quantum states. The physics of our equations also explains some general trends found in current experiments. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.
Persistent Identifierhttp://hdl.handle.net/10722/167077
ISSN
2015 Impact Factor: 3.57
2015 SCImago Journal Rankings: 1.902
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorZhang, Sen_HK
dc.contributor.authorHo, TLen_HK
dc.date.accessioned2012-09-28T04:02:56Z-
dc.date.available2012-09-28T04:02:56Z-
dc.date.issued2011en_HK
dc.identifier.citationNew Journal Of Physics, 2011, v. 13en_HK
dc.identifier.issn1367-2630en_HK
dc.identifier.urihttp://hdl.handle.net/10722/167077-
dc.description.abstractRecent experiments on atom loss in ultra-cold Fermi gases all show a maximum at a magnetic field below Feshbach resonance, where the s-wave scattering length is large (comparable to inter-particle distance) and positive. These experiments have been performed over a wide range of conditions, with temperatures and trap depths spanning three decades. Different groups have come up with different explanations, including the emergence of Stoner ferromagnetism. Here, we show that this maximum is a consequence of two major steps. The first is the establishment of a population of shallow dimers, which is the combined effect of dimer formation through three-body recombination, and the dissociation of shallow dimers back to atoms through collisions. The dissociation process will be temperature dependent and is affected by Pauli blocking at low temperatures. The second is the relaxation of shallow dimers into tightly bound dimers through atom-dimer and dimer-dimer collisions. In these collisions, a significant amount of energy is released. The reaction products leave the trap, leading to trap loss. We have constructed a simple set of rate equations describing these processes. Remarkably, even with only a few parameters, these equations reproduce the loss rate observed in all recent experiments, despite their widely different experimental conditions. Our studies show that the location of the maximum loss rate depends crucially on experimental parameters such as trap depth and temperature. These extrinsic characters show that this maximum is not a reliable probe of the nature of the underlying quantum states. The physics of our equations also explains some general trends found in current experiments. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.en_HK
dc.languageengen_US
dc.publisherInstitute of Physics Publishing Ltd. The Journal's web site is located at http://www.iop.org/EJ/journal/NJPen_HK
dc.relation.ispartofNew Journal of Physicsen_HK
dc.titleAtom loss maximum in ultra-cold Fermi gasesen_HK
dc.typeArticleen_HK
dc.identifier.emailZhang, S: shizhong@hku.hken_HK
dc.identifier.authorityZhang, S=rp01661en_HK
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.doi10.1088/1367-2630/13/5/055003en_HK
dc.identifier.scopuseid_2-s2.0-79956336423en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-79956336423&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume13en_HK
dc.identifier.eissn1367-2630-
dc.identifier.isiWOS:000292001900003-
dc.publisher.placeUnited Kingdomen_HK
dc.identifier.scopusauthoridZhang, S=36678393800en_HK
dc.identifier.scopusauthoridHo, TL=7402460596en_HK

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