Quasiparticle spectra of mixtures of dipolar and non-dipolar condensates at zero and finite temperatures

TL;DR

This paper investigates the collective quasiparticle modes of a mixed dipolar and non-dipolar Bose-Einstein condensate at various temperatures, revealing how dipolar interactions influence phase separation, mode spectra, and miscibility.

Contribution

It introduces a detailed analysis of quasiparticle spectra in dipolar mixtures using Hartree-Fock-Bogoliubov theory, highlighting the effects of dipolar interactions on phase behavior and mode evolution.

Findings

Repulsive dipolar interactions reduce zero-energy modes, indicating increased mixing.

Ground state configurations depend on dipolar strength, with transitions affecting quasiparticle modes.

Finite temperature induces dipole mode hardening and loss of phase coherence.

Abstract

We examine the low-lying collective quasiparticle modes of a quasi-one-dimensional mixture of Bose-Einstein condensates having dipolar and non-dipolar atomic species. The dipolar atomic species have permanent magnetic dipolar moments. We employ Hartree-Fock-Bogoliubov theory to investigate the distinct collective spectra at zero and finite temperatures corresponding to phase separation phenomena stemming from the dipole-dipole interaction of dipolar atomic species. When the dipolar interaction is tuned to be repulsive, the number of zero-energy modes decreases, reflecting the system's tendency towards mixing. For a large number of atoms, we show that the attractive (repulsive) dipolar interaction strengths lead to ground states with non-dipolar (dipolar) atomic species at the periphery, and this leads to a discontinuity in quasiparticle mode evolution. We finally reveal that miscibility driven by thermal fluctuations at finite temperatures exhibits dipole mode hardening, confirmed by the loss of long-range phase coherence through the correlation function. The mode mixing in the dispersion relations ascertains a dipolar strength-dependent miscibility transition and the low-lying quasiparticle mode evolution.