Angular Momentum Transfer induced by an Optical Vortex Beam in a Superconductor

Light with orbital angular momentum, known as an optical vortex beam (OVB), was introduced in 1992 by Allen et al. [1], representing a significant advancement in optical technology. The unique structure and tunability of OVB have since led to extensive research into various applications, including quantum computation, optical manipulation, and optical communication [2]. Despite these advancements, the interaction between OVB and matter remains not fully understood, primarily due to the mismatch between the energy scale and the spatial structure of optical vortices that generate the orbital angular momentum of light. In superconductors, the coherence length is closer in scale to the characteristic wavelength of collective modes in matter [3], allowing OVB to more effectively imprint its spatial structure onto the quantum states of matter. We investigate the dynamics of the order parameter of a superconductor illuminated by OVB by numerically solving the time-dependent Ginzburg-Landau equation and calculating the angular momentum of the superconductor. Our study demonstrates the transfer of the orbital angular momentum of light to the superconductor, resulting from the spatial structure of the light.

[1] L. Allen et al., Phys. Rev. A 45, 8185 (1992).

[2] Y. Shen et al., Light Sci Appl 8, 90 (2019).

[3] T. Mizushima and M. Sato, Phys. Rev. Res. 5, L042004 (2023)