39 research outputs found
Non-destructive measurement of the transition probability in a Sr optical lattice clock
We present the experimental demonstration of non-destructive probing of the
1S0-3P0 clock transition probability in an optical lattice clock with 87Sr
atoms. It is based on the phase shift induced by the atoms on a weak
off-resonant laser beam. The method we propose is a differential measurement of
this phase shift on two modulation sidebands with opposite detuning with
respect to the 1S0-1P1 transition, allowing a detection limited by the photon
shot noise. We have measured an atomic population of 10^4 atoms with a signal
to noise ratio of 100 per cycle, while keeping more than 95% of the atoms in
the optical lattice with a depth of 0.1 mK. The method proves simple and robust
enough to be operated as part of the whole clock setup. This detection scheme
enables us to reuse atoms for subsequent clock state interrogations,
dramatically reducing the loading time and thereby improving the clock
frequency stability.Comment: 4 pages, 5 figure
An Optical Lattice Clock with Spin-polarized 87Sr Atoms
We present a new evaluation of an 87Sr optical lattice clock using spin
polarized atoms. The frequency of the 1S0-3P0 clock transition is found to be
429 228 004 229 873.6 Hz with a fractional accuracy of 2.6 10^{-15}, a value
that is comparable to the frequency difference between the various primary
standards throughout the world. This measurement is in excellent agreement with
a previous one of similar accuracy
Interference-filter-stabilized external-cavity diode lasers
We have developed external-cavity diode lasers, where the wavelength
selection is assured by a low loss interference filter instead of the common
diffraction grating. The filter allows a linear cavity design reducing the
sensitivity of the wavelength and the external cavity feedback against
misalignment. By separating the feedback and wavelength selection functions,
both can be optimized independently leading to an increased tunability of the
laser. The design is employed for the generation of laser light at 698, 780 and
852 nm. Its characteristics make it a well suited candidate for space-born
lasers.Comment: 12 pages, 5 figure
Low noise amplication of an optically carried microwave signal: application to atom interferometry
In this paper, we report a new scheme to amplify a microwave signal carried
on a laser light at =852nm. The amplification is done via a
semiconductor tapered amplifier and this scheme is used to drive stimulated
Raman transitions in an atom interferometer. Sideband generation in the
amplifier, due to self-phase and amplitude modulation, is investigated and
characterized. We also demonstrate that the amplifier does not induce any
significant phase-noise on the beating signal. Finally, the degradation of the
performances of the interferometer due to the amplification process is shown to
be negligible
A high stability semiconductor laser system for a Sr-based optical lattice clock
We describe a frequency stabilized diode laser at 698 nm used for high
resolution spectroscopy of the 1S0-3P0 strontium clock transition. For the
laser stabilization we use state-of-the-art symmetrically suspended optical
cavities optimized for very low thermal noise at room temperature. Two-stage
frequency stabilization to high finesse optical cavities results in measured
laser frequency noise about a factor of three above the cavity thermal noise
between 2 Hz and 11 Hz. With this system, we demonstrate high resolution remote
spectroscopy on the 88Sr clock transition by transferring the laser output over
a phase-noise-compensated 200 m-long fiber link between two separated
laboratories. Our dedicated fiber link ensures a transfer of the optical
carrier with frequency stability of 7 \cdot 10^{-18} after 100 s integration
time, which could enable the observation of the strontium clock transition with
an atomic Q of 10^{14}. Furthermore, with an eye towards the development of
transportable optical clocks, we investigate how the complete laser system
(laser+optics+cavity) can be influenced by environmental disturbances in terms
of both short- and long-term frequency stability.Comment: 9 pages, 9 figures, submitted to Appl. Phys.
New Limits on Coupling of Fundamental Constants to Gravity Using Sr Optical Lattice Clocks
The - clock transition frequency
in neutral Sr has been measured relative to the Cs
standard by three independent laboratories in Boulder, Paris, and Tokyo over
the last three years. The agreement on the level makes
the best agreed-upon optical atomic frequency. We combine
periodic variations in the Sr clock frequency with Hg and
H-maser data to test Local Position Invariance by obtaining the strongest
limits to date on gravitational-coupling coefficients for the fine-structure
constant , electron-proton mass ratio and light quark mass.
Furthermore, after Hg, Yb and H, we add Sr as
the fourth optical atomic clock species to enhance constraints on yearly drifts
of and .Comment: Published version. 4 pages, 4 figure
Limits to the sensitivity of a low noise compact atomic gravimeter
A detailed analysis of the most relevant sources of phase noise in an atomic
interferometer is carried out, both theoretically and experimentally. Even a
short interrogation time of 100 ms allows our cold atom gravimeter to reach an
excellent short term sensitivity to acceleration of g at 1s.
This result relies on the combination of a low phase noise laser system,
efficient detection scheme and good shielding from vibrations. In particular,
we describe a simple and robust technique of vibration compensation, which is
based on correcting the interferometer signal by using the AC acceleration
signal measured by a low noise seismometer.Comment: 30 pages, 14 figure
Geodesy and metrology with a transportable optical clock
partially_open24openGrotti, Jacopo; Koller, Silvio; Vogt, Stefan; Häfner, Sebastian; Sterr, Uwe; Lisdat, Christian; Denker, Heiner; Voigt, Christian; Timmen, Ludger; Rolland, Antoine; Baynes, Fred N.; Margolis, Helen S.; Zampaolo, Michel; Thoumany, Pierre; Pizzocaro, Marco; Rauf, Benjamin; Bregolin, Filippo; Tampellini, Anna; Barbieri, Piero; Zucco, Massimo; Costanzo, Giovanni A.; Clivati, Cecilia; Levi, Filippo; Calonico, DavideGrotti, Jacopo; Koller, Silvio; Vogt, Stefan; Häfner, Sebastian; Sterr, Uwe; Lisdat, Christian; Denker, Heiner; Voigt, Christian; Timmen, Ludger; Rolland, Antoine; Baynes, Fred N.; Margolis, Helen S.; Zampaolo, Michel; Thoumany, Pierre; Pizzocaro, Marco; Rauf, Benjamin; Bregolin, Filippo; Tampellini, Anna; Barbieri, Piero; Zucco, Massimo; Costanzo, Giovanni A.; Clivati, Cecilia; Levi, Filippo; Calonico, David