35 research outputs found
Optical frequency synthesis and measurement using fibre-based femtosecond lasers
We report the synthesis and measurement of an ultra-precise and extremely
stable optical frequency in the telecommunications window around 1543 nm. Using
a fibre-based femtosecond frequency comb we have phase-stabilised a fibre laser
at 194 THz to an optical frequency standard at 344 THz, thus transferring the
properties of the optical frequency standard to another spectral region.
Relative to the optical frequency standard, the synthesised frequency at 194
THz is determined to within 1 mHz and its fractional frequency instability is
measured to be less than 2*10^{-15} at 1 s, reaching 5*10^{-18} after 8000 s.
We also measured the synthesised frequency against a caesium fountain clock:
here the frequency comparison itself contributes less than 4 mHz (2*10^{-17})
to the uncertainty. Our results confirm the suitability of fibre based
frequency comb technology for precision measurements and frequency synthesis,
and enable long-distance comparison of optical clocks by using optical fibres
to transmit the frequency information
Absolute frequency measurement of the magnesium intercombination transition
We report on a frequency measurement of the clock
transition of Mg on a thermal atomic beam. The intercombination
transition has been referenced to a portable primary Cs frequency standard with
the help of a femtosecond fiber laser frequency comb. The achieved uncertainty
is which corresponds to an increase in accuracy of six
orders of magnitude compared to previous results. The measured frequency value
permits the calculation of several other optical transitions from to
the -level system for Mg, Mg and Mg. We describe in
detail the components of our optical frequency standard like the stabilized
spectroscopy laser, the atomic beam apparatus used for Ramsey-Bord\'e
interferometry and the frequency comb generator and discuss the uncertainty
contributions to our measurement including the first and second order Doppler
effect. An upper limit of in one second for the short term
instability of our optical frequency standard was determined by comparison with
a GPS disciplined quartz oscillator.Comment: 8 pages, 8 figure
Ultra-precise measurement of optical frequency ratios
We developed a novel technique for frequency measurement and synthesis, based
on the operation of a femtosecond comb generator as transfer oscillator. The
technique can be used to measure frequency ratios of any optical signals
throughout the visible and near-infrared part of the spectrum. Relative
uncertainties of for averaging times of 100 s are possible. Using a
Nd:YAG laser in combination with a nonlinear crystal we measured the frequency
ratio of the second harmonic at 532 nm to the fundamental at
1064 nm, .Comment: 4 pages, 4 figure
Cold atoms in space: community workshop summary and proposed road-map
We summarise the discussions at a virtual Community Workshop on Cold Atoms in Space concerning the status of cold atom technologies, the prospective scientific and societal opportunities offered by their deployment in space, and the developments needed before cold atoms could be operated in space. The cold atom technologies discussed include atomic clocks, quantum gravimeters and accelerometers, and atom interferometers. Prospective applications include metrology, geodesy and measurement of terrestrial mass change due to, e.g., climate change, and fundamental science experiments such as tests of the equivalence principle, searches for dark matter, measurements of gravitational waves and tests of quantum mechanics. We review the current status of cold atom technologies and outline the requirements for their space qualification, including the development paths and the corresponding technical milestones, and identifying possible pathfinder missions to pave the way for missions to exploit the full potential of cold atoms in space. Finally, we present a first draft of a possible road-map for achieving these goals, that we propose for discussion by the interested cold atom, Earth Observation, fundamental physics and other prospective scientific user communities, together with the European Space Agency (ESA) and national space and research funding agencies
Cold atoms in space: community workshop summary and proposed road-map
We summarise the discussions at a virtual Community Workshop on Cold Atoms in Space concerning the status of cold atom technologies, the prospective scientific and societal opportunities offered by their deployment in space, and the developments needed before cold atoms could be operated in space. The cold atom technologies discussed include atomic clocks, quantum gravimeters and accelerometers, and atom interferometers. Prospective applications include metrology, geodesy and measurement of terrestrial mass change due to, e.g., climate change, and fundamental science experiments such as tests of the equivalence principle, searches for dark matter, measurements of gravitational waves and tests of quantum mechanics. We review the current status of cold atom technologies and outline the requirements for their space qualification, including the development paths and the corresponding technical milestones, and identifying possible pathfinder missions to pave the way for missions to exploit the full potential of cold atoms in space. Finally, we present a first draft of a possible road-map for achieving these goals, that we propose for discussion by the interested cold atom, Earth Observation, fundamental physics and other prospective scientific user communities, together with the European Space Agency (ESA) and national space and research funding agencies.publishedVersio
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Cold atoms in space: community workshop summary and proposed road-map
We summarise the discussions at a virtual Community Workshop on Cold Atoms in Space concerning the status of cold atom technologies, the prospective scientific and societal opportunities offered by their deployment in space, and the developments needed before cold atoms could be operated in space. The cold atom technologies discussed include atomic clocks, quantum gravimeters and accelerometers, and atom interferometers. Prospective applications include metrology, geodesy and measurement of terrestrial mass change due to, e.g., climate change, and fundamental science experiments such as tests of the equivalence principle, searches for dark matter, measurements of gravitational waves and tests of quantum mechanics. We review the current status of cold atom technologies and outline the requirements for their space qualification, including the development paths and the corresponding technical milestones, and identifying possible pathfinder missions to pave the way for missions to exploit the full potential of cold atoms in space. Finally, we present a first draft of a possible road-map for achieving these goals, that we propose for discussion by the interested cold atom, Earth Observation, fundamental physics and other prospective scientific user communities, together with the European Space Agency (ESA) and national space and research funding agencies
Ultragenaue Taktgeber : Optische Uhren in der Anwendung
Im HITec arbeiten Geodäten und Physiker der Leibniz Universität Hannover (LUH) zusammen mit Wissenschaftlern der Physikalisch-Technischen Bundesanstalt (PTB) unter anderem daran, optische Uhren und deren Vergleiche für Anwendungen in der sogenannten relativistischen Geodäsie zu erschließen. Anhand dieser neuen Technologien können unter anderem postglaziale Anhebung von Landmassen oder der Anstieg des Meerwasserspiegels vermessen werden
Optical injection locking-based amplification in phase-coherent transfer of optical frequencies
We demonstrate the use of an optical injection phase locked loop (OIPLL) as a regenerative amplifier for optical frequency transfer applications. The optical injection locking provides high gain within a narrow bandwidth (<100MHz ) and is capable of preserving the fractional frequency stability of the incoming carrier to better than 10-18 at 1000 s. The OIPLL was tested in the field as a mid-span amplifier for the transfer of an ultrastable optical carrier, stabilized to an optical frequency standard, over a 292km long installed dark fiber link. The transferred frequency at the remote end reached a fractional frequency instability of less than 1×10-19 at averaging time of 3200 s
Picoseconds-Accurate Fiber-Optic Time Transfer With Relative Stabilization of Lasers Wavelengths
Optical injection locking based amplification in phase coherent transfer of optical frequencies
We demonstrate use of an optical injection phase locked loop (OIPLL) as a regenerative amplifier for optical frequency transfer applications. The optical injection locking (OIL) provides high gain within a narrow bandwidth (< 100 MHz), and is capable of preserving the fractional frequency stability of the incoming carrier to better than 10^(-18) at 1000 s. The OIPLL was tested in the field as a mid-span amplifier for the transfer of an ultra-stable optical carrier, stabilized to an optical frequency standard, over a 292 km-long installed dark fiber link. The transferred frequency at the remote end reached a fractional frequency instability of less than 1 × 10^(-19) at averaging time of 3200 s.</span