Schmidt, Julian

Date:   Wednesday, Sept. 12, 2018
Time:   14:00
Place:   ETH Zurich, Hönggerberg, HPF G 6
Host:   Jonathan Home, Matt Grau

Optical trapping of ion Coulomb crystals

Julian Schmidt
Albert-Ludwigs-Universität Freiburg, Germany

Ion Coulomb crystals are the key to many applications with trapped ions, as the crystal phonons mediate interaction between ions and allow coupling of electronic and motional states on the quantum level [1]. However, rf-micromotion in ion traps poses fundamental limits for applications with higher-dimensional Coulomb crystals [2] and in ultracold chemistry experiments. Optical dipole traps for trapped ions [3] do not exhibit this micromotion, but only trapping of single ions had been demonstrated thus far.

We now demonstrate trapping of ion crystals [4] consisting of up to six Barium ions in an optical dipole trap aligned with the crystal axis and without confinement by radio-frequency (RF) fields. The dependence on the trap parameters, in particular the interplay of beam waist, laser power and axial confinement by DC electric fields, is investigated. As a proof-of-principle experiment, we detect the center-of-mass and stretch modes for an optically trapped two-ion crystal. Finally, I will present prospects for optical trapping of higher-dimensional Coulomb crystals.

[1] D.J. Wineland, Rev. Mod. Phys. 85, 1103 (2013)
[2] R. Thompson, Contemp. Phys. 1,56, 63-79 (2015)
[3] A. Lambrecht et al., Nat. Phot. 11, 704-707 (2017)
[4] J. Schmidt et al., Phys. Rev. X 8, 021028 (2018)