title: Angular Momentum of Twisted Radiation from an Electron in Spiral Motion.
abstract: We theoretically demonstrate for the first time that a single free electron in circular or spiral motion emits twisted photons carrying well-defined orbital angular momentum along the axis of the electron circulation, in adding to spin angular momentum. We show that, when the electron velocity is relativistic, the radiation field contains harmonic components and the photons of lth harmonic carry lℏ total angular momentum for each. This work indicates that twisted photons are naturally emitted by free electrons and are more ubiquitous in laboratories and in nature than ever thought.
authors.affiliation: Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki 444-8585, Japan.|Sokendai (the Graduated University for Advanced Studies), Okazaki 444-8585, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Katoh
authors.affiliation: Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki 444-8585, Japan.|Sokendai (the Graduated University for Advanced Studies), Okazaki 444-8585, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Fujimoto
authors.affiliation: Muroran Institute of Technology, Muroran 050-0071, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Kawaguchi
authors.affiliation: High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Tsuchiya
authors.affiliation: High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Ohmi
authors.affiliation: Saga Light Source, Tosu 841-0005 Japan.
authors.forename: T
authors.initials: T
authors.lastname: Kaneyasu
authors.affiliation: National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8568, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Taira
authors.affiliation: Nagoya University, Nagoya 464-0814, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Hosaka
authors.affiliation: Nagoya University, Nagoya 464-0814, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Mochihashi
authors.affiliation: Nagoya University, Nagoya 464-0814, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Takashima