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arXiv:2605.26094

Response of a dipolar BEC to Laguerre-Gaussian beam driven STIRAP

Deepu Singh, H. Ghosh, Arpana Saboo, Soumyadeep Halder, Sonjoy Majumder

Published May 25, 2026• 0 citations

Abstract

Coherent light-matter coupling via STIRAP can offer a versatile route to nucleate quantized vortices in Bose-Einstein condensates through the orbital angular momentum transfer from a vortex beam, yet its efficacy in dipolar condensates remains an open question. Can the orbital angular momentum of a Laguerre-Gaussian beam be coherently transferred to a dipolar BEC via STIRAP? We investigate this for a quasi-two-dimensional trapped dipolar condensate using co-propagating Gaussian and Laguerre-Gaussian laser beams. The interplay between long-range dipole-dipole interactions and short-range contact interactions enables access to three interaction-driven phases: superfluid, droplet, and supersolid. We find that the amount of angular momentum transferred from the optical field to the dipolar condensate, along with the nucleation and persistence of vortices, depends strongly on the underlying phases of the dipolar BEC. In the superfluid, STIRAP achieves a near-complete population transfer and nucleates a long-lived quantized vortex, reflecting efficient transfer of angular momentum to the condensate. In the droplet phase, although the vortex remains pinned within the density profile, the angular momentum is partially retained and oscillatory, accompanied by droplet fragmentation and recombination. In the supersolid phase, when the external magnetic field is oriented perpendicular to the LG beam's propagation direction, the emergence of a modulated density distribution along with a slight reduction in inter-droplet coherence leads to vortex delocalization and eventually exits from the condensate along the field direction, yielding a vanishing average angular momentum. However, reorienting the magnetic polarization along the beam propagation direction restores efficient angular momentum transfer and stabilizes the vortex within the supersolid phase.

DOI: 10.48550/arxiv.2605.26094

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We examine a scheme for the optical creation of a superfluid vortex in a trapped Bose-Einstein condensate (BEC), using the stimulated Raman adiabatic passage (STIRAP) technique. By exposing an oblate, axis-symmetric condensate to two co-propagating laser pulses, one can transfer external angular momentum from the light field to the matter wave, if one of the beams is the fundamental Gaussian mode and the other is a Gauss-Laguerre mode of angular momentum

1\hbar

. We demonstrate the complete transfer efficiency by numerical integration of the multi-component Gross-Pitaevskii equation and explain the results with an intuitive and accurate approximation within the Thomas-Fermi limit. In addition, we discuss residual excitations (breathing modes) which occur in the two-dimensional regime and present the Bogoliubov excitation spectrum.

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We examine the use of Laguerre-Gaussian (LG) laser beams in the tripod scheme to create the coupling between spin and orbital angular momentum in a Bose–Einstein condensate (BEC) confined by a harmonic trap. We derive and solve the Gross-Pitaeskii equation numerically to obtain the density distribution of the BEC. Orbital angular momentum from the LG beam is transferred to the BEC, inducing the formation of a giant vortex at the BEC’s centre. The macroscopic flow of spinor BEC around the vortex leads to a persistent spin current in the BEC.

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We examine a scheme for the optical creation of a superfluid vortex in a trapped Bose-Einstein condensate, using the stimulated Raman adiabatic passage technique (STIRAP). By exposing an oblate, axis-symmetric condensate to two copropagating laser pulses, one can transfer external angular momentum from the light field to the matter wave, if one of the beams is the fundamental Gaussian mode and the other is a Gauss-Laguerre mode of angular momentum $1\ensuremath{\hbar}$. We demonstrate the complete transfer efficiency by numerical integration of the multicomponent Gross-Pitaevskii equation and explain the results with an intuitive and accurate approximation within the Thomas-Fermi limit. In addition, we discuss residual excitations (breathing modes) which occur in the two-dimensional regime and present the Bogoliubov excitation spectrum.