In:
National Science Review, Oxford University Press (OUP), Vol. 9, No. 10 ( 2022-11-09)
Abstract:
Atomic Fermi gases provide an ideal platform for studying pairing and superfluid physics, using a Feshbach resonance between closed-channel molecular states and open-channel scattering states. Of particular interest is the strongly interacting regime. We show that the closed-channel fraction ${Z_{{\rm{cc}}}}$ provides an effective probe for important many-body interacting effects, especially through its density dependence, which is absent from two-body theoretical predictions. Here we measure ${Z_{{\rm{cc}}}}$ as a function of interaction strength and the Fermi temperature ${T_{\rm{F}}}$ in a trapped 6Li superfluid throughout the entire Bardeen-Cooper-Schrieffer–Bose-Einstein-condensate crossover, in quantitative agreement with theory when important thermal contributions outside the superfluid core are taken into account. Away from the deep-BEC regime, the fraction ${Z_{\rm cc}}$ is sensitive to ${{{T}}_F}$. In particular, our data show ${Z_{{\rm{cc}}}} \propto T_{\rm{F}}^\alpha $ with $\alpha = {\rm{1/2}}$ at unitarity, in quantitative agreement with calculations of a two-channel pairing fluctuation theory, and $\alpha $ increases rapidly into the BCS regime, reflecting many-body interaction effects as predicted.
Type of Medium:
Online Resource
ISSN:
2095-5138
,
2053-714X
Language:
English
Publisher:
Oxford University Press (OUP)
Publication Date:
2022
detail.hit.zdb_id:
2745465-4
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