Circular Dichroism of Twisted Photons in the Non-Chiral Atomic Matter

Abstract

We calculate the circular dichroism (CD) for absorption of the twisted photons, or optical vortices, by atoms, caused by atomic excitation into discrete energy levels. The effects of photon spin on the rates and cross sections of atomic photo-excitation are considered. It is demonstrated that although for electric dipole transitions the atomic excitation rates depend on the relative orientation of photon spin and orbital angular momentum (OAM), the resulting CD is zero. However, CD is nonzero for atomic transitions of higher multipolarity, peaking in the optical vortex center, resulting in preferred absorption of the photons with their spins aligned with OAM. The effects remain large in a paraxial limit, where analytic expressions are provided. The predicted spin asymmetries are equivalent to OAM dichroism for the fixed photon spin.

8 pages, 10 figures; typos fixed

References in corpus (4)

• Angular Momenta and Spin-Orbit Interaction of Nonparaxial Light in Free Space
• Angular momentum-induced circular dichroism in non-chiral nanostructures
• High-Multipole Excitations of Hydrogen-Like Atoms by Twisted Photons near Phase Singularity
• Far-field measurements of vortex beams interacting with nanoholes

Cited by in corpus (14)

• A Chirality-Based Quantum Leap
• Twisted-ligth--ion interaction: the role of longitudinal fields
• Experimental Verification of Position-Dependent Angular-Momentum Selection Rules for Absorption of Twisted Light by a Bound Electron
• Spin-orbit interactions and chiroptical effects engaging orbital angular momentum of twisted light in chiral and achiral media
• Excitation of E1-forbidden Atomic Transitions with Electric, Magnetic or Mixed Multipolarity in Light Fields Carrying Orbital and Spin Angular Momentum
• Enhancement of the quadrupole interaction of an atom with guided light of an ultrathin optical fiber
• Atomic Spectroscopy with Twisted Photons: Separation of M1--E2 Mixed Multipoles
• Delta baryon photoproduction with twisted photons
• Electrons in intense laser fields with local phase, polarization, and skyrmionic textures
• Resonant sequential two-photon ionization of atoms by twisted and plane-wave light
• Orbital angular momentum beam generation using a free-electron laser oscillator
• Spatio-temporal delay in photoionization by polarization structured laser fields
• Direction-dependent coupling between a nanofiber-guided light field and a two-level atom with an electric quadrupole transition
• Absorption of hybrid fibre modes by Cs atoms in quadrupole transitions