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UID:0-782@lptms.universite-paris-saclay.fr
DTSTART;TZID=Europe/Paris:20210914T110000
DTEND;TZID=Europe/Paris:20210914T120000
DTSTAMP:20210908T124715Z
URL:http://www.lptms.universite-paris-saclay.fr/seminars/seminaire-du-lptm
s-isabelle-bouchoule-lcf/
SUMMARY:Séminaire du LPTMS : Isabelle Bouchoule (LCF) - Petit amphi\, bât
iment Pascal n° 530 - 14 Sep 21 11:00
DESCRIPTION:Effect of losses in correlated quantum gases\nIsabelle Bouchoul
e (Laboratoire Charles Fabry)\nHybrid seminar: onsite + zoom (ID:932 9180
1483\, PW:cuTj9X).\n\nI propose\, during this seminar\, to make a review o
f different results we obtained in the last years\, both theoretical and e
xperimental\, concerning the effect of losses in quantum gases.\n\nLosses
are always present in cold atoms experiments. However in presence of corre
lations between atoms\, evaluating their effect is a difficult theoretical
problem which is mainly unexplored. This is illustrated by our recent wor
k on the effect of losses on a gas with contact interactions: if one makes
the usual assumption that the environment involved in the loss process ha
s a vanishing correlation time\, which is the assumption that leads to the
famous Lindblad equation used so far to describe losses in the context of
cold atoms\, then we show that the energy increase rate in the gas diverg
es in dimensions larger than 1. The description of losses requires either
taking into account the finite correlation time of the reservoir\, or taki
ng into account the finite interaction range between atoms.\n\nIn dimensio
n 1\, such a divergence is absent and for short enough correlation time of
the reservoir\, losses are well described by the Lindblad equation\, even
in the presence of contact interactions. We have investigated the effect
of losses in the Lieb-Liniger model of 1D bosons with contact interaction.
We assume slow losses so that the gas has time to relax at any time. In c
ontrast to chaotic systems which relax towards a thermal state parameteriz
ed by 2 quantities\, the particle density and the energy density\, the loc
al properties of the Lieb-Liniger model after relaxation are parameterized
by a whole function\, the rapidity distribution. We have computed the evo
lution of the rapidity distribution in presence losses\, thus characterizi
ng entirely the effect of slow losses. We observe that losses bring the
system to a non-thermal state\, and we show that a manifestation of the no
n-thermal nature of the state is the breakdown of the popular Tan's relati
on. \n\nIn the particular case when the gas lies into the quasi-condensat
e regime\, we computed the effect of losses within the Bogoliubov descript
ion of the gas. Experimentally\, our measurements\, which concern long wav
e-length collective modes\, are in agreement with those theoretical predic
tions.
CATEGORIES:seminars
LOCATION:Petit amphi\, bâtiment Pascal n° 530\, rue André Rivière\, Ors
ay\, 91405\, France
X-APPLE-STRUCTURED-LOCATION;VALUE=URI;X-ADDRESS=rue André Rivière\, Orsay
\, 91405\, France;X-APPLE-RADIUS=100;X-TITLE=Petit amphi\, bâtiment Pasca
l n° 530:geo:0,0
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