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内容記述 |
Photon vortices are light carrying large orbital angular momentum (OAM) at the quantum level [1]. They can be described by Laguerre-Gaussian or Bessel wave functions, which are waves that are eigenstates of the orbital angular momentum along their propagation direction. Unlike plane-wave photons, photon vortices interact differently with materials because their OAM affects the way they transfer angular momentum.In gamma-ray bursts (GRBs), keV photons can become highly polarised due to strong magnetic fields. This raises the question of whether similar polarisation or angular momentum structures might occur in more extreme environments. We have studied the process by which photon vortices form when electrons undergo spiral motion in magnetic fields as strong as 1012-1013 G, using Landau quantisation. Our calculations show that such vortices are likely to be generated in environments with extremely strong fields, such as magnetars or magnetised accretion disks around black holes [2]. These results support the possibility that photon vortices are not rare, but rather abundant in high-field astrophysical systems.Photon vortices can transfer large total angular momenta to compound nuclei during interactions, which may play an important role in nucleosynthesis processes in the Universe. Liu et al [3] found that the amplitudes of low-multipole giant resonances are suppressed when a photon vortex interacts with a nucleus at relatively small impact parameters.In this paper we calculate the ratios of photon absorption transition probabilities for Bessel-type photon vortices compared to plane-wave photons [4]. Our results show that excitations of nuclear states with large total angular momentum are enhanced by optimising the divergence angle of the incident vortex in momentum space. This implies that photon vortices could selectively excite high angular momentum states. However, the average absorption cross section remains the same.[1] L. Allen, et al. Phys. Rev. A 45, 8185 (1992).[2] T. Maruyama, et al. Phys. Lett. B826. 136779 (2022).[3] Z.-W, Lu, et al., Phys. Rev. Lett. 131, 202502 (2023).[4] T. Maruyama, et al. Astro. J. 975, 51 (2024). |
