34 research outputs found
Cold atom Clocks and Applications
This paper describes advances in microwave frequency standards using
laser-cooled atoms at BNM-SYRTE. First, recent improvements of the Cs
and Rb atomic fountains are described. Thanks to the routine use of a
cryogenic sapphire oscillator as an ultra-stable local frequency reference, a
fountain frequency instability of where
is the measurement time in seconds is measured. The second advance is a
powerful method to control the frequency shift due to cold collisions. These
two advances lead to a frequency stability of at 7\times 10^{-16}^{87}^{133}$Cs fountains.
Finally we give an update on the cold atom space clock PHARAO developed in
collaboration with CNES. This clock is one of the main instruments of the
ACES/ESA mission which is scheduled to fly on board the International Space
Station in 2008, enabling a new generation of relativity tests.Comment: 30 pages, 11 figure
Development of a strontium optical lattice clock for the SOC mission on the ISS
The ESA mission "Space Optical Clock" project aims at operating an optical
lattice clock on the ISS in approximately 2023. The scientific goals of the
mission are to perform tests of fundamental physics, to enable space-assisted
relativistic geodesy and to intercompare optical clocks on the ground using
microwave and optical links. The performance goal of the space clock is less
than uncertainty and
instability. Within an EU-FP7-funded project, a strontium optical lattice clock
demonstrator has been developed. Goal performances are instability below and fractional inaccuracy .
For the design of the clock, techniques and approaches suitable for later space
application are used, such as modular design, diode lasers, low power
consumption subunits, and compact dimensions. The Sr clock apparatus is fully
operational, and the clock transition in Sr was observed with linewidth
as small as 9 Hz.Comment: 12 pages, 8 figures, SPIE Photonics Europe 201
Development of a strontium optical lattice clock for the SOC mission on the ISS
Ultra-precise optical clocks in space will allow new studies in fundamental
physics and astronomy. Within an European Space Agency (ESA) program, the Space
Optical Clocks (SOC) project aims to install and to operate an optical lattice
clock on the International Space Station (ISS) towards the end of this decade.
It would be a natural follow-on to the ACES mission, improving its performance
by at least one order of magnitude. The payload is planned to include an
optical lattice clock, as well as a frequency comb, a microwave link, and an
optical link for comparisons of the ISS clock with ground clocks located in
several countries and continents. Within the EU-FP7-SPACE-2010-1 project no.
263500, during the years 2011-2015 a compact, modular and robust strontium
lattice optical clock demonstrator has been developed. Goal performance is a
fractional frequency instability below 1x10^{-15}, tau^{-1/2} and a fractional
inaccuracy below 5x10^{-17}. Here we describe the current status of the
apparatus' development, including the laser subsystems. Robust preparation of
cold {88}^Sr atoms in a second stage magneto-optical trap (MOT) is achieved.Comment: 27 Pages, 15 figures, Comptes Rendus Physique 201
The Space Optical Clocks Project: Development of high-performance transportable and breadboard optical clocks and advanced subsystems
The use of ultra-precise optical clocks in space ("master clocks") will allow
for a range of new applications in the fields of fundamental physics (tests of
Einstein's theory of General Relativity, time and frequency metrology by means
of the comparison of distant terrestrial clocks), geophysics (mapping of the
gravitational potential of Earth), and astronomy (providing local oscillators
for radio ranging and interferometry in space). Within the ELIPS-3 program of
ESA, the "Space Optical Clocks" (SOC) project aims to install and to operate an
optical lattice clock on the ISS towards the end of this decade, as a natural
follow-on to the ACES mission, improving its performance by at least one order
of magnitude. The payload is planned to include an optical lattice clock, as
well as a frequency comb, a microwave link, and an optical link for comparisons
of the ISS clock with ground clocks located in several countries and
continents. Undertaking a necessary step towards optical clocks in space, the
EU-FP7-SPACE-2010-1 project no. 263500 (SOC2) (2011-2015) aims at two
"engineering confidence", accurate transportable lattice optical clock
demonstrators having relative frequency instability below 1\times10^-15 at 1 s
integration time and relative inaccuracy below 5\times10^-17. This goal
performance is about 2 and 1 orders better in instability and inaccuracy,
respectively, than today's best transportable clocks. The devices will be based
on trapped neutral ytterbium and strontium atoms. One device will be a
breadboard. The two systems will be validated in laboratory environments and
their performance will be established by comparison with laboratory optical
clocks and primary frequency standards. In this paper we present the project
and the results achieved during the first year.Comment: Contribution to European Frequency and Time Forum 2012, Gothenburg,
Swede
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
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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
International timescales with optical clocks
International audienceA key prerequisite for a redefinition of the SI second based on optical atomic clocks is their integration intothe international timescales TAI and UTC. This requires a coordinated programme of clock comparisons to becarried out, to validate the uncertainty budgets of the optical clocks, to anchor their frequencies to the present definitionof the second, and to establish the leading contenders for a new definition. Such a comparison programmeis underway within the EMRP-funded project InternationalTimescales with Optical Clocks (ITOC). Illustrated inFig. 1, this involves four different types of measurementand optical clocks in five different laboratories.Locally, comparisons are being carried out betweenoptical clocks developed in individual laboratories, eitherby direct beat frequency comparison or by using femtosecondcombs to measure optical frequency ratios. To compareoptical clocks developed in different laboratories, twodifferent techniques are being explored, both of whichhave the potential to be applied on an intercontinentalscale. Two comparisons will be performed using transportableoptical clocks, and an improved two-way satellitetime and frequency transfer (TWSTFT) technique based onan increased chip rate is being investigated. In addition tothe direct optical clock comparisons, absolute frequencymeasurements of the optical clocks are also being performed. Several new measurements have already been completedand the current status of the clock comparison programme will be reported at the conference. New methodsdeveloped to analyze the self-consistency of the clock comparison data and to derive optimized values for the frequencyof each optical clock transition will also be described.To support the clock comparison programme, a complete evaluation is being made of all relativistic effects influencingtime and frequency comparisons at the 10-18 level of accuracy, including the gravitational redshifts ofthe clock transition frequencies. Significant progress has been made towards improved determination of the gravitypotential at the sites participating in the optical clock comparisons; gravity surveys have been carried out at alllocations and will feed into the computation of a revised European geoid model.Finally, an experiment is in preparation to demonstrate the future impact that optical atomic clocks could haveon the field of geodesy. This aims to measure with high temporal resolution the gravity potential difference betweentwo well-defined locations separated by a long baseline (~90 km) and a height difference of 1000 m