Frequency ratio measurement of ^171Yb and ^87Sr optical lattice clocks

Abstract

The frequency ratio of the 1 S 0 (F=1/2)-

Absolute frequency measurement of the ${{}^{1}}{{\text{S}}_{0}}$ – ${{}^{3}}{{\text{P}}_{0}}$ transition of171Yb

“…The systematic uncertainty varies for each measurement because of the different density values of both the fountain and optical frequency standard and because of the reduced BBR uncer tainty contribution on the ytterbium after removing the hot window after the first 10 measurements. We applied a statis tical analysis of the data based on the Gauss-Markov theorem [56,57] that considers the correlations between the different measurements coming from the systematic shifts [58] [8,[26][27][28] and abso lute frequencies deduced from optical ratio measurements with 87 Sr frequency standards [24,25,29]. To deduce these values we used the recommended frequency of 87 Sr …”

“…Optical lattice fre quency standards have now demonstrated systematic fractional uncertainties at the 10 −17 -10 −18 level [5] and also an unprec edented frequency stability [23] opening the path for frequency comparisons beyond the uncertainty of the realization of the SI units in hundreds of seconds [24]. In particular, different groups developed ytterbium optical lattice frequency stand ards worldwide [23][24][25][26] and the spin and angular momentum forbidden transition S 1 0 -P 3 0 of ytterbium 171 at 578 nm is recommended as a secondary representation of the SI second by the International Committee for Weights and Measures (CIPM). Absolute frequency measurement of this transition has been performed relative to the realization of the second with caesium standards at the National Institute of Standards and Technology (NIST) [8], at the National Metrology Institute of Japan (NMIJ) [27,28], and at the Korea Research Institute of Standards and Science (KRISS) [26].…”

Building a better atomic clock

“…A testament to the realizability of this system is the increasing number of OLC experiments popping up around the world, especially with the Strontium isotope which exhibits laser cooling and trapping wavelengths all accessible via diode lasers [22,26,27,28,29,30]. Perhaps unsurprisingly, the benefits imparted by using ever more stable laser local oscillators to interrogate the atoms make the state-of-the-art versions of these clocks very sensitive to thermal noise of both the cavity spacer and mirror coatings, and presently limits miniaturization of these systems.…”

“…Furthermore, future experiments that seemed promising required the use of optical access at approximately 30 degree intervals (30,60,90,120), putting stringent restrictions on what our main chamber would need to look like. This following chapter will shed light on the design decisions made for the SrIII apparatus, will document its construction, and will offer a glimpse at some of the many experiments possible with this new apparatus.…”

All-polarization-maintaining, single-port Er:fiber comb for high-stability comparison of optical lattice clocks

“…Low intrinsic phase noise with PM architecture is demonstrated by applying a nonlinear amplifying loop mirror (NALM). 17,18) In linking multiple optical frequencies, Er:fiber combs with a multibranch configuration, where each port consists of an Er-doped fiber amplifier (EDFA) and a highly nonlinear fiber (HNLF), have been employed, 3,19) as it allows sufficient output power per comb tooth optimized for the single frequency. In such a multibranch comb, the phase noise in different branches introduces the instability of ∼10 −16 at 1 s. 10,11) A record high instability of 4 × 10 −16 (τ=s) −1=2 has been demonstrated for synchronous clock comparison between strontium (Sr)-and ytterbium (Yb)-based optical lattice clocks, 3) in which the instability is mainly limited by the Dick effect 20) due to the frequency noise of the multibranch comb.…”