Development of an Apparatus for a Strontium Optical Lattice Optical Frequency Standard
Author(s)
Hill, Ian Robert
Type
Thesis
Abstract
Accurate time keeping is critical to the function and advancement of many
human endeavours. Atomic clocks based on a microwave transition in atomic
Cs have served as primary frequency standards to realise the SI second since
their formal adoption in 1967. State-of-the-art, laser cooled, Cs fountains now
routinely operate with fractional frequency uncertainties below the 10⁻¹⁵ level
in laboratories throughout the world. Over the last decade, efforts to build
frequency standards based on optical transitions have come to fruition and
potential inaccuracies below the 10⁻¹⁷ level have been demonstrated. Such
standards point to the future of time keeping and much development is being
pursued to realise the potential of these 'next generation' optical clocks. One
such approach, on which this work focusses, relies on a 'magic' wavelength
optical lattice trap to provide (almost) Doppler- and recoil-free confinement
of atoms during clock interrogation. At this 'magic' wavelength, light induced
perturbation of the clock states is equal and so cancels precisely. This thesis
describes the design and implementation of an optical lattice frequency
standard apparatus based on 88Sr held in a 1D optical lattice. A review of the
development of atomic frequency metrology is given from a historical viewpoint
and the technology and limitations of current methods discussed. To tackle
the blackbody radiation shift, which currently presents the greatest limitation
to the Sr lattice clock, imposing at the 10⁻¹⁶ level, a scheme to measure the
blackbody radiation shift coefficient at the 10⁻¹⁷ level is developed. Techniques
to laser cool and trap atomic strontium are described and the implementation
detailed. All laser systems required for clock operation are described including
the design and implementation of extended-cavity diode lasers for precision
spectroscopy. Details relevant to the eventual operation of the apparatus are
discussed.
human endeavours. Atomic clocks based on a microwave transition in atomic
Cs have served as primary frequency standards to realise the SI second since
their formal adoption in 1967. State-of-the-art, laser cooled, Cs fountains now
routinely operate with fractional frequency uncertainties below the 10⁻¹⁵ level
in laboratories throughout the world. Over the last decade, efforts to build
frequency standards based on optical transitions have come to fruition and
potential inaccuracies below the 10⁻¹⁷ level have been demonstrated. Such
standards point to the future of time keeping and much development is being
pursued to realise the potential of these 'next generation' optical clocks. One
such approach, on which this work focusses, relies on a 'magic' wavelength
optical lattice trap to provide (almost) Doppler- and recoil-free confinement
of atoms during clock interrogation. At this 'magic' wavelength, light induced
perturbation of the clock states is equal and so cancels precisely. This thesis
describes the design and implementation of an optical lattice frequency
standard apparatus based on 88Sr held in a 1D optical lattice. A review of the
development of atomic frequency metrology is given from a historical viewpoint
and the technology and limitations of current methods discussed. To tackle
the blackbody radiation shift, which currently presents the greatest limitation
to the Sr lattice clock, imposing at the 10⁻¹⁶ level, a scheme to measure the
blackbody radiation shift coefficient at the 10⁻¹⁷ level is developed. Techniques
to laser cool and trap atomic strontium are described and the implementation
detailed. All laser systems required for clock operation are described including
the design and implementation of extended-cavity diode lasers for precision
spectroscopy. Details relevant to the eventual operation of the apparatus are
discussed.
Date Issued
2012-06
Date Awarded
2012-07
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
Curtis, Elizabeth
Sauer, Ben
Publisher Department
Physics
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)