Arts & Sciences Events
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Arts & Sciences
[PAST EVENT] AMO Seminar
June 25, 2014
4pm
Abstract:
Optical clocks based on ultra-cold, lattice trapped alkaline-earth-like atoms, interrogated on the ultra-narrow 1S0?3P0 transition, promise timing performance at unprecedented levels. Recently, our ytterbium optical lattice clock demonstrated record frequency stability of 1.6?10-18 in fractional units. Evaluation of the clock uncertainty at the 10-18 level requires characterization of the atomic response to two main systematic frequency shifts: one due to ambient blackbody radiation (BBR) and one due to residual Stark effects from the lattice, both of which I cover in this talk. Uncertainty in the BBR shift stems from imprecise knowledge of the thermal environment surrounding the atoms. I detail the construction and operation of an in-vacuum, thermally-regulated radiation shield, which permits laser cooling and trapping while enabling an absolute temperature measurement below the 20mK level. Additionally, while operation of the optical lattice at the magic wavelength cancels the scalar Stark shift (since both clock states shift equally), higher-order vector and two-photon hyperpolarizability shifts remain. To evaluate these effects, we implement a lattice enhancement cavity around the atoms. The resulting ten-fold increase of the lattice intensity provides a significant lever arm for precise measurement of these effects.
Optical clocks based on ultra-cold, lattice trapped alkaline-earth-like atoms, interrogated on the ultra-narrow 1S0?3P0 transition, promise timing performance at unprecedented levels. Recently, our ytterbium optical lattice clock demonstrated record frequency stability of 1.6?10-18 in fractional units. Evaluation of the clock uncertainty at the 10-18 level requires characterization of the atomic response to two main systematic frequency shifts: one due to ambient blackbody radiation (BBR) and one due to residual Stark effects from the lattice, both of which I cover in this talk. Uncertainty in the BBR shift stems from imprecise knowledge of the thermal environment surrounding the atoms. I detail the construction and operation of an in-vacuum, thermally-regulated radiation shield, which permits laser cooling and trapping while enabling an absolute temperature measurement below the 20mK level. Additionally, while operation of the optical lattice at the magic wavelength cancels the scalar Stark shift (since both clock states shift equally), higher-order vector and two-photon hyperpolarizability shifts remain. To evaluate these effects, we implement a lattice enhancement cavity around the atoms. The resulting ten-fold increase of the lattice intensity provides a significant lever arm for precise measurement of these effects.