87Sr lattice clock with inaccuracy below 10 -15.

ArticleinPhysical Review Letters 98(8):083002 · March 2007with13 Reads
Source: PubMed
Abstract
Aided by ultrahigh resolution spectroscopy, the overall systematic uncertainty of the 1S0-3P0 clock resonance for lattice-confined 87Sr has been characterized to 9 x 10(-16). This uncertainty is at a level similar to the Cs-fountain primary standard, while the potential stability for the lattice clocks exceeds that of Cs. The absolute frequency of the clock transition has been measured to be 429 228 004 229 874.0(1.1) Hz, where the 2.5 x 10(-15) fractional uncertainty represents the most accurate measurement of a neutral-atom-based optical transition frequency to date.
    • "In Boulder we have paid particular attention to the effect of atomic interactions on the clock transition frequency. Initial experiments on Sr with measurement precision of 10 −15 revealed no atomic density-dependent frequency shift [26] . However , when the measurement precision improved further, we uncovered density-dependent frequency shifts with nuclear spin-polarized fermions for the JILA Sr clock [4] and the NIST Yb clock [5]. "
    [Show abstract] [Hide abstract] ABSTRACT: Optical lattice clocks have made significant leaps forward in recent years, demonstrating the ability to measure time/frequency at unprecedented levels. Here we highlight this progress, with a particular focus on research efforts at NIST and JILA. We discuss advances in frequency instability and the characterization of key systematic effects, with a brief outlook to the future.
    Full-text · Article · May 2015
    • "Frequency measurements wrt primary caesium atomic clocks. JILA07: [36]; SYRTE08: [37], JILA08: [38], UT09: [39], PTB11: [34], NICT-a 12: [40], NICT-b 12: [41], SYRTE 13: [30], PTB13: [31], NMIJ14: [32]. The full vertical line indicates the value for use as a secondary representation of the second with the estimated uncertainty (dashed lines) recommended by the CIPM [42]. "
    [Show abstract] [Hide abstract] ABSTRACT: The rapid increase in accuracy and stability of optical atomic clocks compared to the caesium atomic clock as primary standard of time and frequency asks for a future re-definition of the second in the International System of Units (SI). The status of the optical clocks based on either single ions in radio-frequency traps or on neutral atoms stored in an optical lattice is described with special emphasis of the current work at the Physikalisch-Technische Bundesanstalt (PTB). Besides the development and operation of different optical clocks with estimated fractional uncertainties in the 10^-18 range, the supporting work on ultra-stable lasers as core elements and the means to compare remote optical clocks via transportable standards, optical fibers, or transportable clocks is reported. Finally, the conditions, methods and next steps are discussed that are the prerequisites for a future re-definition of the second.
    Full-text · Article · Jan 2015
    • "Laser cooling of neutral atoms has played a fundamental role and caused a profound impact in many fields such as atomic clock, Bose-Einstein condensation, quantum degenerate gases, and ultracold molecules and so on1234. Up to now, the basic Doppler cooling (for example magneto-optical trap---MOT) mechanism of momentum transfer from a laser beam in near resonance with a almost closed two-level, freely moving atom, leads to a several hundred microKelvin for alkali-metal atoms that is proportional the linewidth of the atomic transition [5]. "
    [Show abstract] [Hide abstract] ABSTRACT: We present an investigation of two-color magneto-optical trap (MOT) based on cesium 6S 1/2 -6P 3/2 -8S 1/2 ladder-type atomic system, which employs the optical forces due to photon scattering from the excited states 6P 3/2 (F'=5)-8S 1/2 (F"=4) (794.6nm) transition, and replaces one pair of the three pairs of cooling laser beams operating on a single-photon red detuning to the 6S 1/2 (F=4)-6P 3/2 (F'=5) (852.3nm) transition in a conventional 3D MOT, and this two-color MOT can efficiently cool and trap atoms in a vapor cell on both the negative and positive sides of the two-photon resonance. We found an interesting phenomenon that when the 794.6nm cooling laser is tuned resonant with the 6P 3/2 (F'=5)-8S 1/2 (F"=4) transition and the intensity of 852.3nm cooling laser is too strong, the number of trapped atoms in the two-color MOT will be suppressed due to the heating from photons scattering. These works should be helpful to increasing optical thickness of trapped atoms and the practical applications of two-color MOT.
    Full-text · Article · Jul 2014 · Comptes Rendus Physique
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