Microwave lensing frequency shift of the PHARAO laser-cooled microgravity atomic clock

Peterman, P.; Gibble, Kurt; Laurent, P.; Salomon, Christophe

doi:10.1088/0026-1394/53/2/899

Cited by 9 publications

(31 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Several projects on space CACs, such as ACES, PARCS, and RACE, have been proposed in the last few decades 19 . For example, the ACES mission, which consists of a caesium CAC called PHARAO, a hydrogen maser, as well as a package for frequency comparisons and distribution, aims to search for drifts in fundamental constants and measure the gravitational red shift with improved precision 20 – 26 . The PHARAO clock is expected to operate in space with a frequency stability of 1.0 × 10 −13 τ −1/2 ( τ is the average time in second) and an accuracy below 3 × 10 −16 (ref.…”

Section: Introductionmentioning

confidence: 99%

In-orbit operation of an atomic clock based on laser-cooled 87Rb atoms

et al. 2018

View full text Add to dashboard Cite

Atomic clocks based on laser-cooled atoms are widely used as primary frequency standards. Deploying such cold atom clocks (CACs) in space is foreseen to have many applications. Here we present tests of a CAC operating in space. In orbital microgravity, the atoms are cooled, trapped, launched, and finally detected after being interrogated by a microwave field using the Ramsey method. Perturbing influences from the orbital environment on the atoms such as varying magnetic fields and the passage of the spacecraft through Earth’s radiation belt are also controlled and mitigated. With appropriate parameters settings, closed-loop locking of the CAC is realized in orbit and an estimated short-term frequency stability close to 3.0 × 10−13τ−1/2 has been attained. The demonstration of the long-term operation of cold atom clock in orbit opens possibility on the applications of space-based cold atom sensors.

show abstract

Section: Introductionmentioning

confidence: 99%

In-orbit operation of an atomic clock based on laser-cooled 87Rb atoms

et al. 2018

View full text Add to dashboard Cite

show abstract

“…Because atoms in a fountain are localized to less than a microwave wavelength, the resonant microwave dipole forces do not yield resolved photon recoils, but instead act as weak focusing and defocusing lenses on the atom wave packets. The resulting shift depends on the clock geometry and is typically 6×10 17 to 9×10 17 for fountains [4][5][6][7][8]17], and larger for the microgravity clock PHARAO, 11.4×10 17 [22]. There is currently some controversy since the recent NIST treatment [16,18] predicts a much smaller shift, 1.6×10 17 , disagreeing with the prior results [4][5][6][7]17].…”

Section: Microwave Lensing Frequency Shiftsmentioning

confidence: 90%

Systematic Effects in Atomic Fountain Clocks

Gibble

2016

J. Phys.: Conf. Ser.

Self Cite

View full text Add to dashboard Cite

Abstract. We describe recent advances in the accuracies of atomic fountain clocks. New rigorous treatments of the previously large systematic uncertainties, distributed cavity phase, microwave lensing, and background gas collisions, enabled these advances. We also discuss background gas collisions of optical lattice and ion clocks and derive the smooth transition of the microwave lensing frequency shift to photon recoil shifts for large atomic wave packets.

show abstract

“…We derive the microwave lensing frequency shift, including additional detection apertures, in appendix A. Near optimal microwave amplitude, b 1 ≈ 1, we get a very good approximation [48,55,57,58] to the full expression (A.2) if we neglect the small variation of the state detection in CSF1 and CSF2:…”

Section: Microwave Lensingmentioning

confidence: 94%

“…To calculate the microwave lensing frequency shifts of CSF1 and CSF2, we use their specific fountain parameters and geometries, as for the DCP calculations. The apertures that clip the atom cloud play a central role in the microwave lensing shift and, for CSF2, two detection apertures contribute in addition to the usual two restrictive apertures in most fountain clocks [48,55,57,58].…”

Section: Microwave Lensingmentioning

confidence: 99%

See 1 more Smart Citation

Advances in the accuracy, stability, and reliability of the PTB primary fountain clocks

Weyers,

Gerginov,

Kazda

et al. 2018

Preprint

View full text Add to dashboard Cite

Improvements of the systematic uncertainty, frequency instability, and long-term reliability of the two caesium fountain primary frequency standards CSF1 and CSF2 at PTB (Physikalisch-Technische Bundesanstalt) are described. We have further investigated many of the systematic effects and made a number of modifications of the fountains. With an optically stabilized microwave oscillator, the quantum projection noise limited frequency instabilities are improved to 7.2 × 10 −14 (τ /1 s) −1/2 for CSF1 and 2.5×10 −14 (τ /1 s) −1/2 for CSF2 at high atom density. The systematic uncertainties of CSF1 and CSF2 are reduced to 2.74 × 10 −16 and 1.71 × 10 −16 , respectively. Both fountain clocks regularly calibrate the scale unit of International Atomic Time (TAI) and the local realization of Coordinated Universal Time, UTC(PTB), and serve as references to measure the frequencies of local and remote optical frequency standards.

show abstract

Microwave lensing frequency shift of the PHARAO laser-cooled microgravity atomic clock

Cited by 9 publications

References 21 publications

In-orbit operation of an atomic clock based on laser-cooled 87Rb atoms

In-orbit operation of an atomic clock based on laser-cooled 87Rb atoms

Systematic Effects in Atomic Fountain Clocks

Advances in the accuracy, stability, and reliability of the PTB primary fountain clocks

Contact Info

Product

Resources

About