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Uncertainty evaluation of an 171Yb optical lattice clock at NMIJ
摘要： We report an uncertainty evaluation of an 171Yb optical lattice clock with a total fractional uncertainty of 3.6 × 10^{-16}, which is mainly limited by the lattice-induced light shift and the blackbody radiation shift. Our evaluation of the lattice-induced light shift, the density shift, and the second-order Zeeman shift is based on an interleaved measurement where we measure the frequency shift using the alternating stabilization of a clock laser to the 6s2 1S0–6s6p 3P0 clock transition with two different experimental parameters. In the present evaluation, the uncertainties of two sensitivity coefficients for the lattice-induced hyperpolarizability shift d incorporated in a widely used light shift model by RIKEN and the second-order Zeeman shift aZ are improved compared with the uncertainties of previous coefficients. The hyperpolarizability coefficient d is determined by investigating the trap potential depth and the light shifts at the lattice frequencies near the two-photon transitions 6s6p3P0–6s8p3P0, 6s8p3P2, and 6s5f3F2. The obtained values are d = ?1.1(4) μHz and aZ = ?6.6(3) Hz/mT2. These improved coefficients should reduce the total systematic uncertainties of Yb lattice clocks at other institutes.
关键词： precise measurement,optical lattice clock,optical frequency comb,Frequency standards,SI second
更新于2025-09-23 15:23:52
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[IEEE 2019 Joint Conference of the IEEE International Frequency Control Symposium anEuropean Frequency and Time Forum (EFTF/IFC) - Orlando, FL, USA (2019.4.14-2019.4.18)] 2019 Joint Conference of the IEEE International Frequency Control Symposium and European Frequency and Time Forum (EFTF/IFC) - Ultrastable Laser System Using Room-Temperature Optical Cavity with 4.8??10 <sup>a??17</sup> Thermal Noise Limit
摘要： A new clock laser system using an optical cavity with 4.8×10-17 thermal noise limit has been developed for rapid evaluation of ytterbium lattice clocks. This was realized by using a 30-cm-long ULE cavity, fused-silica mirror substrates, and crystalline mirror coatings. The frequency stability of the beating signal between the new clock laser and the old clock laser was limited by the latter. The linewidth and the frequency stability of the new clock laser will be measured by comparing the frequency between two similar systems.
关键词： linewidth,ytterbium,optical lattice clock,frequency stability,optical cavity,clock laser,crystalline coating
更新于2025-09-19 17:13:59
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Accurate laser frequency locking to optical frequency combs under low-signal-to-noise-ratio conditions
摘要： We demonstrate a method for accurately locking the frequency of a continuous-wave laser to an optical frequency comb under conditions where the signal-to-noise ratio is low, too low to accommodate other methods. Our method is typically orders of magnitude more accurate than conventional wavemeters and can considerably extend the usable wavelength range of a given optical frequency comb. We illustrate our method by applying it to the frequency control of a dipole lattice trap for an optical lattice clock, a representative case where our method provides significantly better accuracy than other methods.
关键词： optical lattice clock,optical frequency combs,laser frequency locking,low-signal-to-noise-ratio
更新于2025-09-19 17:13:59