Non-Hermitian Ferromagnetism in an Ultracold Fermi Gas

Abstract

We develop a non-Hermitian effective theory for a repulsively interacting Fermi gas in the excited branch. The on-shell $T$-matrix is employed as a complex-valued interaction term, which describes a repulsive interaction between atoms in the excited branch and a two-body inelastic decay to the attractive branch. To see the feature of this model, we have addressed, in the weak coupling regime, the excitation properties of a repulsive Fermi polaron as well as the time-dependent number density. The analytic expressions obtained for these quantities qualitatively show a good agreement with recent experiments. By calculating the dynamical transverse spin susceptibility in the random phase approximation, we show that a ferromagnetic system with nonzero polarization undergoes a dynamical instability and tends towards a heterogeneous phase.

6 pages, 2 figures

References in corpus (16)

• Many-Body Physics with Ultracold Gases
• Theory of ultracold Fermi gases
• Attractive and repulsive Fermi polarons in two dimensions
• Itinerant Ferromagnetism in a Fermi Gas of Ultracold Atoms
• Repulsive Fermi polarons in a resonant mixture of ultracold ${}^6$Li atoms
• Strongly paired fermions: Cold atoms and neutron matter
• Excitation spectra and rf-response near the polaron-to-molecule transition from the functional renormalization group
• Decay of polarons and molecules in a strongly polarized Fermi gas
• Superfluid Fermi atomic gas as a quantum simulator for the study of neutron-star equation of state
• Spin drag in an ultracold Fermi gas on the verge of a ferromagnetic instability
• Lindblad Equation for the Inelastic Loss of Ultracold Atoms
• Interaction induced dynamical $\mathcal{P}\mathcal{T}$ symmetry breaking in dissipative Fermi-Hubbard models
• Cold Atom Quantum Simulator for Dilute Neutron Matter
• Non-equilibrium strong-coupling theory for a driven-dissipative ultracold Fermi gas in the BCS-BEC crossover region
• Exploring emergent heterogeneous phases in strongly repulsive Fermi gases
• Finite range and upper branch effects on itinerant ferromagnetism in repulsive Fermi gases: Bethe-Goldstone ladder resummation approach

Cited by in corpus (4)

• Phase diagram of non-Hermitian BCS superfluids in a dissipative asymmetric Hubbard model
• Spin transport between polarized Fermi gases near the ferromagnetic phase transition
• Spin-Depairing-Induced Exceptional Fermionic Superfluidity
• Itinerant ferromagnetism of a dipolar Fermi gas with Raman-induced spin-orbit coupling