title: Magnetic-dipole transitions in highly charged ions as a basis of ultraprecise optical clocks.
abstract: We evaluate the feasibility of using magnetic-dipole (M1) transitions in highly charged ions as a basis of an optical atomic clockwork of exceptional accuracy. We consider a range of possibilities, including M1 transitions between clock levels of the same fine-structure and hyperfine-structure manifolds. In highly charged ions these transitions lie in the optical part of the spectra and can be probed with lasers. The most direct advantage of our proposal comes from the low degeneracy of clock levels and the simplicity of atomic structure in combination with negligible quadrupolar shift. We demonstrate that such clocks can have projected fractional accuracies below the 10^{-20}-10^{-21} level for all common systematic effects, such as blackbody radiation, Zeeman, ac-Stark, and quadrupolar shifts.
authors.affiliation: Institute of Laser Physics SB RAS, pr. Akademika Lavrent'eva 13/3, Novosibirsk 630090, Russia and Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia and Novosibirsk State Technical University, pr. Karla Marksa 20, Novosibirsk 630073, Russia and Russian Quantum Center, Skolkovo, Moscow Reg., 143025, Russia.
authors.forename: V I
authors.initials: VI
authors.lastname: Yudin
authors.affiliation: Institute of Laser Physics SB RAS, pr. Akademika Lavrent'eva 13/3, Novosibirsk 630090, Russia and Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia and Russian Quantum Center, Skolkovo, Moscow Reg., 143025, Russia.
authors.forename: A V
authors.initials: AV
authors.lastname: Taichenachev
authors.affiliation: Department of Physics, University of Nevada, Reno, Nevada 89557, USA.
authors.forename: A
authors.initials: A
authors.lastname: Derevianko