Southwest Quantum Information and Technology

Efficient sympathetic cooling in mixed barium and ytterbium ion chains

Presenting Author: Liudmila Zhukas, University of Washington
Contributing Author(s): Tomasz P. Sakrejda, Boris B. Blinov

138Ba+ (barium) and 171Yb+ (ytterbium) ions are excellent qubit candidates due to unique properties of these species. In one proposal of using mixed species linear chains, ytterbium is used as the main computational qubit species whereas barium undergoes cooling; mechanical coupling of barium and ytterbium thus provides sympathetic cooling of the latter. However, even the relatively small 25% mass difference between barium and ytterbium can reduce the vibrational modes coupling that affects cooling of the ytterbium ions. Here we Doppler cool barium ions in mixed barium-ytterbium chains confined in a linear RF trap and measure the motional average occupation quantum numbers of all radial normal modes. The full set of orderings in a chain of two barium and two ytterbium ions have been probed, and we show that the motional average occupation quantum numbers of all chain configurations strongly depends on the trap aspect ratio. We demonstrate efficient sympathetic cooling of all radial normal modes for the trap aspect ratio of 2.9.

(Session 5 : Sunday from 5:00pm - 7:00pm)