arXiv subjects

Harsimranjit Kaur

Publications and source records attributed to Harsimranjit Kaur.

4 recordsLinked to original sources

arXiv2026

Potential-defect-driven collective modes of one-dimensional two-component quantum droplets

We examine a one-dimensional binary mixture of ultradilute quantum droplets in the presence of a central potential defect. The properties of the potential strength and the number of atoms exhibit distinct polarization transitions and low-lying ollective excitation spectra. The balance of (attractive) Lee-Huang-Yang quantum fluctuations and repulsive mean-field interactions results in a self-bound quantum droplet in a potential well. However, the potential barrier causes the polarization transition with the number of atoms, which is reflected in the excitation spectrum as a discontinuity and softening of the quasiparticle modes. We reveal that the critical number of atoms for the transition decreases as the attractive intercomponent interaction increases. Finally, the quench time dynamics of the interaction in potential barrier and well show the localization and diffusive fragmented droplets of two-component systems.

cond-mat.quant-gas↗

arXiv2026

Structural transition and fragmentation of vortex lattices in rotating tilted dipolar Bose-Einstein condensate

We investigate the vortex lattices of harmonically confined quasi-two-dimensional tilted rotational dipolar Bose-Einstein condensates. By employing an extended Gross-Pitaevskii equation for a rotating condensate, we reveal the structural transformation of vortices from square to triangular lattices as the tilt of dipolar bosons relative to the polarization axis approaches a critical angle. When the tilt of the magnetic dipoles surpasses the magic angle, the condensate elongates diagonally and becomes devoid of vortices. Moreover, we include the Lee-Huang-Yang correction, which enables the formation of vortices in the elongated condensate. Additionally, when dipoles are oriented perpendicular to the polarization axis, the Lee-Huang-Yang correction results in the fragmentation of condensates under strong rotation. The quench dynamics of the rotational frequency demonstrate the development of vortex lattices; however, with a strong rotational quench, the condensate remains free of vortices. Our numerical analysis highlights the beyond mean-field effects of the rotational properties of anisotropic dipolar bosons, which can be observed in current dipolar quantum gas experiments.

cond-mat.quant-gas↗

arXiv2025

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

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.

cond-mat.quant-gas↗

arXiv2024

Collective modes of two-species Bose-Einstein condensates in a Josephson junction barrier

The ultracold atoms are an ideal platform to implement atomtronics and Josephson junctions analogous to superconducting circuits. The collective modes of a Bose gas split by a potential barrier have been known. However, the role of barriers on the collective excitation spectra of ultracold atomic mixtures has not been examined. Here, we examine the low-lying collective modes of (an)harmonically trapped quasi-one-dimensional Bose-Einstein condensates in a Josephson barrier by employing the variational approach and Bogoliubov theory. We first show that the anharmonicity of the external potential leads to an increase in the critical barrier strength of mode softening in a single-species condensate. The Josephson barrier drives the softening of in-phase and out-of-phase dipole modes of two-species Bose-Einstein condensates, and consequently leads to two additional zero-energy Goldstone modes in the miscible phase, in agreement with the variational approach. Furthermore, the sandwich immiscible state results in an additional Goldstone mode due to the barrier, in contrast to the spatially symmetry-broken side-by-side profile. Our results unveil the distinct collective response of the Josephson barrier in binary mixtures owing to interspecies atomic correlations.

cond-mat.quant-gas↗