Collective phenomena in quasi-two-dimensional fermionic polar molecules: band renormalization and excitons

Abstract

We theoretically analyze a quasi-two-dimensional system of fermionic polar molecules in a harmonic transverse confining potential. The renormalized energy bands are calculated by solving the Hartree-Fock equation numerically for various trap and dipolar interaction strengths. The inter-subband excitations of the system are studied in the conserving time-dependent Hartree-Fock (TDHF) approximation from the perspective of lattice modulation spectroscopy experiments. We find that the excitation spectrum consists of both inter-subband particle-hole excitation continuums and anti-bound excitons, arising from the anisotropic nature of dipolar interactions. The excitonic modes capture the majority of the spectral weight. We also evaluate the inter-subband transition rates in order to investigate the nature of the excitonic modes and find that they are anti-bound states formed from particle-hole excitations arising from several subbands. Our results indicate that the excitonic effects are present for interaction strengths and temperatures accessible in current experiments with polar molecules.

21 pages, 12 figures

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• Density instabilities in a two-dimensional dipolar Fermi gas
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• Ground-state and dynamical properties of two-dimensional dipolar Fermi liquids
• Collective excitations of quasi-two-dimensional trapped dipolar fermions: transition from collisionless to hydrodynamic regime
• Properties of the density-wave phase of a two-dimensional dipolar Fermi gas
• Universal behavior of repulsive two-dimensional fermions in the vicinity of the quantum freezing point
• Wigner Crystallization in Two Dimensions: Evolution from Long- to Short-Ranged Forces
• On cold gases with anisotropic interactions
• 2D Gapless Topological Superfluids Generated by Pairing Phases
• Thermalization of dipole oscillations in confined systems by rare collisions