Collective oscillations of Bose-Einstein condensates in a synthetic magnetic field

We study the collective oscillations of spin-orbit-coupled Bose-Einstein condensates in the presence of position-dependent detuning. Specifically, we explore the quadrupole modes of the system using both numerical and analytical approaches based on the Gross-Pitaevskii equation and hydrodynamic theory. Due to spin-orbit coupling and the synthetic magnetic field, the xy scissors mode couples with a superposition of the three diagonal quadrupole modes (x2,y2, and z2), resulting in the characteristic beating effect. The remaining two scissors modes, xz and yz, are coupled, giving rise to a Lissajous-like pattern that is highly sensitive to the excitation method and orientation of the synthetic magnetic field. Furthermore, we find that anisotropic interactions as well as the direction of the synthetic magnetic field, can significantly influence the oscillation amplitude and frequency of the quadrupole modes. These findings highlight the potential of Bose-Einstein condensates under synthetic magnetic fields for quantum sensing applications, such as magnetic field gradient measurements, and provide a promising foundation for future experimental research and technological development.