Imprinting spiral Higgs waves onto superconductors with vortex beams

Abstract: A vortex beam, akin to a quantized vortex in superfluids, possesses inherent orbital angular momentum (OAM), resulting in the propagation of a spiral-shaped wavefront. Here we demonstrate that a pulsed vortex beam with OAM in the terahertz frequency band can induce a spiral Higgs wave, which is a spiral-shaped oscillation mode of the superconducting order parameter. By utilizing the gauge-invariant theory for the superconducting order, we demonstrate that the phase mode is driven to screen the longitudinal magnetic field of the vortex beam, which facilitates the imprinting of the spiral-shaped wavefront and the transfer of OAM to the condensate. Furthermore, we find that increasing the OAM of light amplifies the intensity of the third harmonic generation. These findings highlight the potential of terahertz vortex beams as a spectroscopic probe of collective modes.