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CQOM Colloquium - Vincent Jarlaud and Julian Berengut

Info about event


Tuesday 23 October 2018,  at 15:00 - 17:00


Vincent Jarlaud, IFA

Title: 2D coulomb crystals

15:15-15:30 Questions and coffee/tea and cake

Invited talk

Julian Berengut, School of Physics, University of New South Wales, Sydney 2052, Australia

Title: Atomic calculations in multivalent ions with applications to novel clocks



Several recent experiments have necessitated new methods of calculation of electronic spectra of complicated atoms and ions. Systems of interest include many-valence-electron atoms [1], highly charged ions with open shells [2], and atoms where hole excitations play an important role [3]. Accurate calculations are required for the design and characterization of nuclear clocks and highly-charged-ion clocks.

In this talk I will present calculations of ions that may be of interest for new clocks. The variety of highly charged ions (HCIs) available provides new opportunities for experiment. Choosing HCIs near level crossings allows optical transitions with high sensitivity to variations of the fine-structure constant, and many opportunities to control systematics. Other ions can provide electronic bridges to the low-lying nuclear transitions in Th-229 and U-235.

Our calculations are performed using AMBiT, a modern, open-source implementation of the particle-hole CI+MBPT (configuration interaction and many-body perturbation theory) method [4]. Limiting off-diagonal elements of the Hamiltonian allows the CI to achieve saturation even in difficult multivalent atoms and ions. The particle-hole formalism allows important hole configurations (where the core is unfrozen) to be treated on an equal footing with other configurations.


          [1]      N. Leefer et al., Phys. Rev. Lett. 111 060801 (2013)

          [2]      F. Toretti et al., Phys. Rev. A 95 042503 (2017)

          [3]      N. Huntemann et al., Phys. Rev. Lett. 116, 063001 (2016)

          [4]      J. C. Berengut, Phys. Rev. A 94, 012502 (2016)