Title: Trapped-ion optical clocks: Telling time and testing physics at the quantum limit
Abstract: Optical transitions in trapped, laser-cooled ions can provide an extremely well-controlled frequency reference for atomic clocks. The most stable and accurate atomic clocks now make measurements with total uncertainty approaching 1×10-18. The Ion Storage Group at NIST develops optical clocks based on the 1S0-3P0 resonance in 27Al+. To perform precision spectroscopy on this atomic system we use the basic building block of a quantum computer, the two-qubit gate, which transfers information from 27Al+ to a second ion species held in the same trap. I will introduce these systems and present recent frequency comparisons between them and other optical clocks at NIST. These comparisons provide valuable data for international time/frequency standards and can test our fundamental theories including relativity and the Standard Model. I will also describe quantum metrology techniques that have allowed us to approach the quantum limit for stability in a 27Al+ single-ion clock.