Related papers: Accurate spectroscopy of Sr atoms
The $^1\mathrm{S}_0$-$^3\mathrm{P}_0$ clock transition frequency $\nu_\text{Sr}$ in neutral $^{87}$Sr has been measured relative to the Cs standard by three independent laboratories in Boulder, Paris, and Tokyo over the last three years.…
We report the first direct excitation of the strongly forbidden 5s2 1S0-5s5p 3P0 transition in 87Sr. Its frequency is 429 228 004 235 (20) kHz. A resonant laser creates a small leak in a magneto-optical trap (MOT): atoms build up to the…
We present absolute frequency measurements of 2S_{1/2}-nS_{1/2} two-photon transitions with n = 8, 9, and 10 in a cryogenic beam of atomic hydrogen. Each transition has been measured with a fractional uncertainty of approximately…
Isotope shift spectroscopy with narrow optical transitions provides a benchmark for atomic structure calculations and has also been proposed as a way to constrain theories predicting physics beyond the Standard Model. Here, we have measured…
Direct frequency-comb spectroscopy is used to probe the absolute frequencies of $6S_{1/2}$-$8S_{1/2}$ two-photon transitions of atomic cesium in hot vapor environment. By utilizing the coherent control method of temporally splitting the…
We report direct measurements of the frequency ratio of the 642 THz ${}^2S_{1/2} (F=0)$--${}^2F_{7/2} (F=3)$ electric octupole transition in ${}^{171}\mathrm{Yb}^+$ and the 429 THz ${}^1S_0$--${}^3P_0$ transition in ${}^{87}\mathrm{Sr}$. A…
We have measured the 1S - 2S transition frequency in atomic hydrogen via two photon spectroscopy on a 5.8 K atomic beam. We obtain $f_{1S-2S} = 2 466 061 413 187 035 (10)$ Hz for the hyperfine centroid. This is a fractional frequency…
The pursuit of ever more precise measures of time and frequency is likely to lead to the eventual redefinition of the second in terms of an optical atomic transition. To ensure continuity with the current definition, based on a microwave…
We report a stability below $7\times 10{}^{-17}$ of two independent optical lattice clocks operating with bosonic ${}^{88}$Sr isotope. The value (429228066418008.3(1.9)${}_{syst}$(0.9)${}_{stat}$~Hz) of the absolute frequency of the…
Transition frequencies of atoms and ions are among the most accurately accessible quantities in nature, playing important roles in pushing the frontiers of science by testing fundamental laws of physics, in addition to a wide range of…
In this paper we report the evaluation of an optical lattice clock based on neutral mercury down to a relative uncertainty of $1.7\times 10^{-16}$. Comparing this characterized frequency standard to a Cs atomic fountain we determine the…
This article presents spectroscopy results of the $5s5p{\;^3}P_0 \rightarrow 5s5d{\;^3}D_1$ transition in all isotopes of laser cooled Sr atoms and the utility of this transition for repumping application. By employing the $5s5p{\;^{3}…
We report on a series of 42 measurements of the transition frequency of the 429~THz (5s$^2$)~$^1$S$_0$--(5s5p)~$^3$P$_0$ line in $^{87}$Sr taken over three years from 2017 to 2019. They have been performed at the Physikalisch-Technische…
Precision spectroscopy of atomic hydrogen is an important way to test bound-state quantum electrodynamics (QED), one of the building blocks of the Standard Model. In its simplest form, such a test consists of the comparison of a measured…
We report high-precision frequency ratio measurements between optical atomic clocks based on $^{27}$Al$^+$, $^{171}$Yb, and $^{87}$Sr. With total fractional uncertainties at or below $3.2 \times 10^{-18}$, these measurements meet an…
We report absolute frequency measurements of the molecular iodine P(46) 5-4 $a_{1}$, $a_{10}$, and $a_{15}$ hyperfine transitions at 647 nm with a fiber-based frequency comb. The light source is based on a Littrow-type external-cavity diode…
We report on an absolute frequency measurement of the ${\rm Lu}^{+}\,(^{3}\rm D_1)$ standard frequency which is defined as the hyperfine-average of $^{1}\rm S_0$ to $^{3}\rm D_1$ optical clock transitions in $^{176}{\rm Lu}^{+}$. The…
The frequency comb created by a femtosecond mode-locked laser and a microstructured fiber is used to phase coherently measure the frequencies of both the Hg^+ and Ca optical standards with respect to the SI second as realized at NIST. We…
We perform Ramsey-Bord\'e spectroscopy on laser-cooled magnesium atoms in free fall to measure the 1S0 \rightarrow 3P1 intercombination transition frequency. The measured value of 655 659 923 839 730 (48) Hz is consistent with our former…
We have measured the isotope shift of the narrow quadrupole-allowed 5 2S1/2 - 4 2D5/2 transition in 86Sr+ relative to the most abundant isotope 88Sr+. This was accomplished using high-resolution laser spectroscopy of individual trapped…