Improved Absolute Frequency Measurement of the $^{171}$Yb Optical Lattice Clock towards a Candidate for the Redefinition of the Second

Abstract

We demonstrate an improved absolute frequency measurement of the 1S0–3P0 clock transition at 578 nm in 171Yb atoms in a one-dimensional optical lattice. The clock laser linewidth is reduced to ≈2 Hz by phase-locking the laser to an ultrastable neodymium-doped yttrium aluminum garnet (Nd:YAG) laser at 1064 nm through an optical frequency comb with an intracavity electrooptic modulator to achieve a high servo bandwidth. The absolute frequency is determined as 518 295 836 590 863.1(2.0) Hz relative to the SI second, and will be reported to the International Committee for Weights and Measures.

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 …”

Precision measurement with optical frequency combs and clocks

“…The absolute frequency of the 1 S0(F = 1/2) -3 P0(F = 1/2) clock transition in 171 Yb is determined to be 518 295 836 590 863.1(2.0) Hz with respect to the SI second [10]. Figure 2 shows the comparison of the absolute frequencies measured at three different institutes: the NIST [14], the KRISS [15] and the NMIJ [10].…”

“…We also report on the absolute frequency measurement of a 171 Yb lattice clock [9,10] and the development of clock lasers [11]. Recently, we have also started a Sr optical lattice clock project [12,13] for the measurement of the Yb/Sr frequency ratio with an uncertainty beyond the Cs limit.…”

“…Measurement results of the absolute frequency of the 171 Yb clock transition by three different institutes: the NIST[14], the KRISS[15], and the NMIJ[10].…”

Second harmonic generation at 399 nm resonant on the ^1S_0−^1P1 transition of ytterbium using a periodically poled LiNbO_3 waveguide

“…Cold-atom experiments with ytterbium (Yb) atoms are of great interest in various research fields, including optical lattice clocks [1][2][3][4], quantum simulation [5,6], and quantum information processing [7,8]. Among these fields, optical lattice clocks have recently attracted considerable attention thanks to demonstrations of uncertainties at the 10 −18 level [9][10][11] In experiments with cold Yb atoms, high power light sources operating at 399 nm resonant on the 1 S 0 − 1 P 1 transition are used to cool atoms to a millikelvin temperature.…”