Hartree-Fock treatment of Fermi polarons using the Lee-Low-Pine transformation

Abstract

We consider the Fermi polaron problem at zero temperature, where a single impurity interacts with non-interacting host fermions. We approach the problem starting with a Frohlich-like Hamiltonian where the impurity is described with canonical position and momentum operators. We apply the Lee-Low-Pine (LLP) transformation to change the fermionic Frohlich Hamiltonian into the fermionic LLP Hamiltonian which describes a many-body system containing host fermions only. We adapt the self-consistent Hartree-Fock (HF) approach, first proposed by Edwards, to the fermionic LLP Hamiltonian in which a pair of host fermions with momenta $\mathbf{k}$ and ${\mathbf{k}}^{\prime }$ interact with a potential proportional to $\mathbf{k}\cdot {\mathbf{k}}^{\prime }$. We apply the HF theory, which has the advantage of not restricting the number of particle-hole pairs, to repulsive Fermi polarons in one dimension. When the impurity and host fermion masses are equal our variational ansatz, where HF orbitals are expanded in terms of free-particle states, produces results in excellent agreement with McGuire's exact analytical results based on the Bethe ansatz. This work raises the prospect of using the HF ansatz and its time-dependent generalization as building blocks for developing all-coupling theories for both equilibrium and nonequilibrium Fermi polarons in higher dimensions

11 pages, 6 figures

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Cited by in corpus (6)

• Emergence of a sharp quantum collective mode in a one-dimensional Fermi polaron
• The ground state of polaron in an ultracold dipolar Fermi gas
• Bose polaron in spherically symmetric trap potentials: Ground states with zero and lower angular momenta
• Disorder in order: Localization without randomness in a cold atom system
• Mass-gap description of heavy impurities in Fermi gases
• Several fermions strongly interacting with a heavy mobile impurity in a one-dimensional harmonic trap