Beliaev damping in quasi-2D dipolar condensates

Abstract

We study the effects of quasiparticle interactions in a quasi-two dimensional (quasi-2D), zero-temperature Bose-Einstein condensate of dipolar atoms, which can exhibit a roton-maxon feature in its quasiparticle spectrum. Our focus is the Beliaev damping process, in which a quasiparticle collides with the condensate and resonantly decays into a pair of quasiparticles. Remarkably, the rate for this process exhibits a highly non-trivial dependence on the quasiparticle momentum and the dipolar interaction strength. For weak interactions, the low energy phonons experience no damping, and the higher energy quasiparticles undergo anomalously weak damping. In contrast, the Beliaev damping rates become anomalously large for stronger dipolar interactions, as rotons become energetically accessible as final states. Further, we find a qualitative anisotropy in the damping rates when the dipoles are tilted off the axis of symmetry. Our study reveals the unconventional nature of Beliaev damping in dipolar condensates, and has important implications for ongoing studies of equilibrium and non-equilibrium dynamics in these systems.

4+ pages, 3 figures. Comments welcome

References in corpus (16)

• A High Phase-Space-Density Gas of Polar Molecules
• Bose-Einstein condensation of chromium
• Bose-Einstein Condensation of Erbium
• Observing the Rosensweig instability of a quantum ferrofluid
• Ultracold dense samples of dipolar RbCs molecules in the rovibrational and hyperfine ground state
• Strong dipolar effects in a quantum ferrofluid
• Quantum degenerate dipolar Fermi gas
• Roton-type mode softening in a quantum gas with cavity-mediated long-range interactions
• Radial and angular rotons in trapped dipolar gases
• Stability of quasi-two-dimensional Bose-Einstein condensates with dominant dipole-dipole interactions
• Softening of Roton and Phonon Modes in a Bose-Einstein Condensate with Spin-Orbit Coupling
• Roton-Maxon Excitation Spectrum of Bose Condensates in a Shaken Optical Lattice
• Roton spectroscopy in a harmonically trapped dipolar Bose-Einstein condensate
• Quasi-particle Lifetime in a Mixture of Bose and Fermi Superfluids
• Two-dimensional Bose gas of tilted dipoles: roton instability and condensate depletion
• Damping of long wavelength collective modes in spinor Bose-Fermi mixtures

Cited by in corpus (5)

• Dynamical excitation of maxon and roton modes in a Rydberg-Dressed Bose-Einstein Condensate
• Breathing Mode of a Bose-Einstein Condensate Immersed in a Fermi Sea
• Beliaev Damping in Spin-$\frac{1}{2}$ Interacting Bosons with Spin-Orbit Coupling
• Stoner-Wohlfarth switching of the condensate magnetization in a dipolar spinor gas and the metrology of excitation damping
• Rotons and their damping in elongated dipolar Bose-Einstein condensates