High-momentum tails as magnetic structure probes for strongly-correlated SU(κ) fermionic mixtures in one-dimensional traps - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Physical Review A : Atomic, molecular, and optical physics [1990-2015] Année : 2016

High-momentum tails as magnetic structure probes for strongly-correlated SU(κ) fermionic mixtures in one-dimensional traps

Résumé

A universal k −4 decay of the large-momentum tails of the momentum distribution, fixed by Tan's contact coefficients, constitutes a direct signature of strong correlations in a short-range interacting quantum gas. Here we consider a repulsive multicomponent Fermi gas under harmonic confinement, as in the experiment of Pagano et al. [Nat. Phys. 10, 198 (2014)], realizing a gas with tunable SU (κ) symmetry. We exploit an exact solution at infinite repulsion to show a direct correspondence between the value of the Tan's contact for each of the κ components of the gas and the Young tableaux for the SN permutation symmetry group identifying the magnetic structure of the ground-state. This opens a route for the experimental determination of magnetic configurations in cold atomic gases, employing only standard (spin-resolved) time-of-flight techniques. Combining the exact result with matrix-product-states simulations, we obtain the Tan's contact at all values of repulsive interactions. We show that a local density approximation (LDA) on the Bethe-Ansatz equation of state for the homogeneous mixture is in excellent agreement with the results for the harmonically confined gas. At strong interactions, the LDA predicts a scaling behavior of the Tan's contact. This provides a useful analytical expression for the dependence on the number of fermions, number of components and on interaction strength. Moreover, using a virial approach, we study the Tan's contact behaviour at large temperatures and in the limit of infinite interactions and we show that it increases with the temperature and the number of components. At zero temperature, we predict that the weight of the momentum distribution tails increases with interaction strength and the number of components if the population per component is kept constant. This latter property was experimentally observed in Ref. [Nat. Phys. 10, 198 (2014)].
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hal-01518883 , version 1 (05-05-2017)

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Jean Decamp, Johannes Jünemann, Mathias Albert, Matteo Rizzi, Anna Minguzzi, et al.. High-momentum tails as magnetic structure probes for strongly-correlated SU(κ) fermionic mixtures in one-dimensional traps. Physical Review A : Atomic, molecular, and optical physics [1990-2015], 2016, 94, ⟨10.1103/PhysRevA.94.053614⟩. ⟨hal-01518883⟩
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