Unconventional pairing in one-dimensional systems of a few mass-imbalanced ultracold fermions

Abstract

We study the ground-state properties of a two-component fermionic mixture effectively confined in a one-dimensional harmonic trap. We consider scenarios when numbers of particles in components are the same but particles have different masses. We examine whether it is possible to detect signatures of an unconventional pairing between opposite-spin fermions in the presence of attractive interactions. For this purpose, we perform the exact diagonalization of the many-body Hamiltonian and study the two-particle reduced density matrix. In agreement with expectations, we confirm that the many-body ground state is dominated by conventional pairs with a negligible total momentum for a small mass imbalance. Furthermore, we show that for sufficiently large mass ratios the domination of fundamentally different pairs is established and the Fulde-Ferrell-Larkin-Ovchinnikov phase is supported. Finally, we argue that the two mechanisms can coexist in the regime of moderate mass ratios. Due to the current experimental progress in obtaining ultra-cold fermionic systems in a few-body regime, our predictions may have some importance for the upcoming experiments.

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• Pairing patterns in one-dimensional spin- and mass-imbalanced Fermi gases
• Reduced density matrix approach to ultracold few-fermion systems in one dimension
• Enhanced visibility of the Fulde-Ferrell-Larkin-Ovchinnikov state in one dimensional Bose-Fermi mixtures near the immiscibility point
• Simulating artificial one-dimensional physics with ultra-cold fermionic atoms: three exemplary themes
• Spin-imbalanced ultracold Fermi gases in a two-dimensional array of tubes
• Unconventional pairing in few-fermion systems at finite temperature
• Few-body perspective on fermionic pairing in one spatial dimension
• Unit-density SU(3) Fermi-Hubbard Model with Spin Flavor Imbalance
• Unconventional pairing in few-fermion systems tuned by external confinement
• Composite Bosons Superposition Ansatz Approach to One-Dimensional Trapped Few-Fermion Systems