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Article Dans Une Revue Physical Review A : Atomic, molecular, and optical physics [1990-2015] Année : 2012

Impurity in a Fermi sea on a narrow Feshbach resonance: A variational study of the polaronic and dimeronic branches

Yvan Castin

Résumé

We study the problem of a single impurity of mass M immersed in a Fermi sea of particles of mass m. The impurity and the fermions interact through a s-wave narrow Feshbach resonance, so that the Feshbach length R* naturally appears in the system. We use simple variational ansatz, limited to at most one pair of particle-hole excitations of the Fermi sea and we determine for the polaronic and dimeronic branches the phase diagram between absolute ground state, local minimum, thermo-dynamically unstable regions (with negative effective mass), and regions of complex energies (with negative imaginary part). We also determine the closed channel population which is experimentally accessible. Finally we identify a non-trivial weakly attractive limit where analytical results can be obtained, in particular for the crossing point between the polaronic and dimeronic energy branches.
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Dates et versions

hal-01312796 , version 1 (10-05-2016)

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Christian Trefzger, Yvan Castin. Impurity in a Fermi sea on a narrow Feshbach resonance: A variational study of the polaronic and dimeronic branches. Physical Review A : Atomic, molecular, and optical physics [1990-2015], 2012, 85 (5), pp.053612. ⟨10.1103/PhysRevA.85.053612⟩. ⟨hal-01312796⟩
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