Related papers: Single-Ion Atomic Clock with $3\times10^{-18}$ Sys…

We report a measurement of the absolute frequency of the 1S0-3P0 transition in the 171Yb optical lattice clock at KRISS (KRISS-Yb1) for 14 months, which was referenced to the SI second by primary and secondary standards worldwide via TAI…

We study the $^1$S$_0 - ^3$D$_2$ and $^1$S$_0 - ^3$D$_3$ transitions in Cu II and the $^1$S$_0 - ^3$P$^{\rm o}_2$ transition in Yb III as possible candidates for the optical clock transitions. A recently developed version of the…

We report a direct measurement of the $7s\ ^2S_{1/2}\rightarrow$ $7p\ ^2P_{3/2}$ electric dipole transition frequency in $^{226}$Ra$^{+}$. With a single laser-cooled radium ion we determine the transition frequency to be 785722.11(3) GHz by…

The systematic shifts of the transition frequencies in the molecular hydrogen ions are of relevance to ultra-high-resolution radio-frequency, microwave and optical spectroscopy of these systems, performed in ion traps. We develop the…

The highest performance atomic clocks are based on interrogation of ultra-narrow optical transitions. There is now significant interest in developing these systems as a source of GNSS-independent time in deployed, dynamic environments. We…

We propose a high-performance atomic clock based on the 1.81 PHz transition between the ground and first-excited state of doubly ionized lead. Utilizing an even isotope of lead, both clock states have $I=J=F=0$, where $I$, $J$, and $F$ are…

Here we present a liquid nitrogen-cooled Ca^+ optical clock with an overall systematic uncertainty of 3*10^-18. In contrast with the room-temperature Ca^+ optical clock that we have reported previously, the temperature of the blackbody…

Divalent atoms and ions with a singlet $S$ ground state and triplet $P$ excited state form the basis of many high-precision optical atomic clocks. Along with the metastable $^{3}\mathrm{P}_{0}$ clock state, these atomic systems also have a…

Optical atomic clocks promise timekeeping at the highest precision and accuracy, owing to their high operating frequencies. Rigorous evaluations of these clocks require direct comparisons between them. We have realized a high-performance…

We measured the absolute frequency of the optical clock transition 1S0 (F = 1/2) - 3P0 (F = 1/2) of 171Yb atoms confined in a one-dimensional optical lattice and it was determined to be 518 295 836 590 863.5(8.1) Hz. The frequency was…

We report improved frequency ratio measurement with $^{87}$Sr and $^{171}$Yb optical lattice clocks at the National Metrology Institute of Japan (NMIJ). The $^{87}$Sr optical lattice clock is enhanced with several major modifications and is…

With the advent of optical clocks featuring fractional frequency uncertainties on the order of $10^{-17}$ and below, new applications such as chronometric levelling with few-cm height resolution emerge. We are developing a transportable…

By varying the density of an ultracold $^{88}$Sr sample from $10^9$ cm$^{-3}$ to $> 10^{12}$ cm$^{-3}$, we make the first definitive measurement of the density-related frequency shift and linewidth broadening of the $^1S_0$ - $^3P_1$…

We present a method that uses radio-frequency pulses to cancel the quadrupole shift in optical clock transitions. Quadrupole shifts are an inherent inhomogeneous broadening mechanism in trapped ion crystals, limiting current optical ion…

We report on a frequency ratio measurement of a ${}^{199}$Hg-based optical lattice clock referencing a ${}^{87}$Sr-based clock. Evaluations of lattice light shift, including atomic-motion-dependent shift, enable us to achieve a total…

We present a transportable optical clock (TOC) with $^{87}$Sr. Its complete characterization against a stationary lattice clock resulted in a systematic uncertainty of ${7.4 \times 10^{-17}}$ which is currently limited by the statistics of…

We observe two-body loss of ${}^3P_0$ ${}^{87}$Sr atoms trapped in a one-dimensional optical lattice. We measure loss rate coefficients for atomic samples between 1 and 6 $\mu$K that are prepared either in a single nuclear-spin-sublevel or…

For the isotope $^{229}$Th we investigate the possibility of two-photon laser spectroscopy of the nuclear clock transition (148.38 nm) using intense monochromatic laser field at twice the wavelength (296.76 nm). Our estimates show that due…

This dissertation reports on the development of a low-power, high-stability miniature atomic frequency standard based on 171Yb+ ions. The ions are buffer-gas cooled and held in a linear quadrupole trap that is integrated into a sealed,…

We report an s-wave collisional frequency shift of an atomic clock based on fermions. In contrast to bosons, the fermion clock shift is insensitive to the population difference of the clock states, set by the first pulse area in Ramsey…