Peter Blythe

This thesis was based in NPL.

Click here to download thesis: Optical Frequency Measurement and Ground State Cooling of Single Trapped Yb+ Ion

Title: Optical frequency measurement and ground state cooling of single trapped Yb⁺ ions

Abstract: 

The thesis describes experiments on single laser-cooled ions of Yb⁺ in a radio frequency ion trap.

The ion is laser-cooled on the 369 nm ²S_1/2→²P_1/2 electric dipole transition, and high resolution spectroscopy of the 467 nm ²S_1/2→²F_7/2 electric octupole `clock' transition has been performed.

The 467 nm transition can be used as an optical frequency standard. To this end, several absolute optical frequency measurements of the F = 0, m_F = 0 → F = 3, m_F = 0 component in ¹⁷¹Yb⁺ have been made with a femtosecond laser frequency comb generator. The comb was referenced to a hydrogen maser which forms part of the clock ensemble used to generate the UTC(NPL) timescale. During the work described in this thesis, the linewidth of the 467 nm probe laser has been narrowed from 4 kHz to 200 Hz, increasing the measurement resolution.

The frequency measurements have been supported by a full investigation of the systematic frequency shifts of the octupole transition, including the AC Stark, second-order Zeeman, quadrupole, DC Stark, second-order Doppler and blackbody shifts.

Cooling an ion of ¹⁷²Yb⁺ to the ground motional state of the ion trap by 'EIT cooling' on the 369 nm transition has been investigated, both by numerical simulation and experiment. A new technique for measuring the temperature of a trapped ion without the use of a narrow transition has been developed. A new experimental control system has been implemented to assist in the EIT cooling experiments.

Issue Date: August 2005

Supervisor: Thompson, Richard

                    Webster, Stephen

Item Type:  Physics PhD Thesis