The Higgs mode in a superfluid of Dirac fermions

Abstract

We study the Higgs amplitude mode in the s-wave superfluid state on the honeycomb lattice inspired by recent cold atom experiments. We consider the attractive Hubbard model and focus on the vicinity of a quantum phase transition between semi-metal and superfluid phases. On either side of the transition, we find collective mode excitations that are stable against decay into quasiparticle-pairs. In the semi-metal phase, the collective modes have "Cooperon" and exciton character. These modes smoothly evolve across the quantum phase transition, and become the Anderson-Bogoliubov mode and the Higgs mode of the superfluid phase. The collective modes are accommodated within a window in the quasiparticle-pair continuum, which arises as a consequence of the linear Dirac dispersion on the honeycomb lattice, and allows for sharp collective excitations. Bragg scattering can be used to measure these excitations in cold atom experiments, providing a rare example wherein collective modes can be tracked across a quantum phase transition.

8 pages, 2 figures. Includes supplementary materials

References in corpus (14)

• Many-Body Physics with Ultracold Gases
• The `Higgs' Amplitude Mode at the Two-Dimensional Superfluid-Mott Insulator Transition
• Absence of a Spin Liquid Phase in the Hubbard Model on the Honeycomb Lattice
• Spontaneous Magnon Decays
• Quantum Magnets under Pressure: Controlling Elementary Excitations in TlCuCl3
• BCS-BEC crossover on the two-dimensional honeycomb lattice
• Detecting the Amplitude Mode of Strongly Interacting Lattice Bosons by Bragg Scattering
• The Higgs mode in a two-dimensional superfluid
• Fate of the Higgs mode near quantum criticality
• Spin-stretching modes in anisotropic magnets: spin-wave excitations in the multiferroic Ba2CoGe2O7
• The Amplitude Mode in the Quantum Phase Model
• Tight binding models for ultracold atoms in honeycomb optical lattices
• The Nambu sum rule and the relation between the masses of composite Higgs bosons
• Superfluidity of Dirac Fermions in a Tunable Honeycomb Lattice: Cooper Pairing, Collective Modes, and Critical Currents

Cited by in corpus (15)

• Direct observation of Higgs mode oscillations in the pump-probe photoemission spectra of electron-phonon mediated superconductors
• Non-relativistic dynamics of the amplitude (Higgs) mode in superconductors
• Nonlinear light-Higgs coupling in superconductors beyond BCS: Effects of the retarded phonon-mediated interaction
• The Nambu sum rule and the relation between the masses of composite Higgs bosons
• Collective excitations of a trapped Fermi gas at finite temperature
• Cooperon condensation and intra-valley pairing states in honeycomb Dirac systems
• Collective excitations of a BCS superfluid in the presence of two sublattices
• Hidden charge-conjugation, parity, and time-reversal symmetries and massive Goldstone (Higgs) modes in superconductors
• Higgs amplitude mode in massless Dirac fermion systems
• Long-lived Higgs modes in strongly correlated condensates
• Excitonic collective modes in Weyl semi-metals
• Collective excitation and stability of flow-induced gapless Fermi superfluids
• Superfluid properties of an ultracold Fermi gas with an orbital Feshbach resonance in the BCS-BEC crossover region
• Gapless chiral excitons in thin films of topological insulators
• Linear response of a superfluid Fermi gas inside its pair-breaking continuum