An Optical Clock Based on a Single Trapped ¹⁹⁹ Hg ⁺ Ion

Abstract

Microwave atomic clocks have been the de facto standards for precision time and frequency metrology over the past 50 years, finding widespread use in basic scientific studies, communications, and navigation. However, with its higher operating frequency, an atomic clock based on an optical transition can be much more stable. We demonstrate an all-optical atomic clock referenced to the 1.064-petahertz transition of a single trapped 199 Hg ϩ ion. A clockwork based on a mode-locked femtosecond laser provides output pulses at a 1-gigahertz rate that are phase-coherently locked to the optical frequency. By comparison to a laser-cooled calcium optical standard, an upper limit for the fractional frequency instability of 7 ϫ 10 Ϫ15 is measured in 1 second of averaging-a value substantially better than that of the world's best microwave atomic clocks.

Attosecond‐precision ultrafast photonics

“…By stabilizing the spacing (repetition rate, f rep ) and the offset (carrier-envelope offset frequency, f ceo ) of the frequency comb, one can measure an optical frequency with unprecedented accuracy [2,3]. Optical frequency combs produced by mode-locked lasers have enabled major advances in highprecision laser spectroscopy [4,5] and provided the clockwork for optical atomic clocks [6][7][8]. The importance of these developments has been recognized by the 2005 Nobel Prize in Physics, shared by Theodor Hänsch and John Hall for their contributions to the frequency comb technology.…”

Full Stabilization of a Microresonator-Based Optical Frequency Comb

“…Furthermore, generation of a microwave beat note at the comb's mode spacing frequency is demonstrated, enabling direct stabilization to a microwave frequency standard. DOI Introduction.-Optical frequency combs [1,2] have become a powerful tool for high precision spectroscopy over the past decade and are moreover used for various applications such as broadband gas sensing [3], molecular fingerprinting [4], optical clocks [5], and attosecond physics [6]. Frequency comb generation naturally occurs in modelocked lasers whose emission spectrum constitutes an ''optical frequency ruler'' and consists of phase coherent modes with frequencies f m f CEO mf rep (where m is the number of the comb mode).…”

Black-body radiation shifts and theoretical contributions to atomic clock research

“…The resulting wave functions are used to calculate matrix elements and other properties. The CI + MBPT approach permits one to incorporate core excitations in the CI method by including certain perturbation theory terms into an effective Hamiltonian (17). The one-body …”

“…In 2006, the International Committee for Weights and Measures (CIPM) recommended that the following transitions frequencies be used as secondary representations of the second [5]: ground-state hyperfine microwave transition in 87 Rb [6], [7], 5s 2 S 1/2 − 4d 2 D 5/2 optical transition of the 88 Sr + ion [8], [9], 5d 10 6s 2 S 1/2 (F = 0) − 5d 9 6s 2 2 D 5/2 (F = 2) optical transition in 199 Hg + ion [10], [11], 6s 2 S 1/2 (F = 0) − 5d 2 D 5/2 (F = 2) optical transition in 171 Yb + ion [12], [13] and 5s 2 1 S 0 − 5s5p 3 P 0 transition in 87 Sr neutral atom [14], 1 Email: msafrono@udel.edu [15], [16]. With better stability and accuracy, as well as extremely low systematic perturbations, such optical frequency standards can reach a systematic fractional uncertainty of order 10 −18 [9], [17]. The ability to develop more precise optical frequency standards will open ways of improving global positioning systems, tracking deep-space probes, performing accurate measurements of fundamental constants, and testing underlying postulates of physics.…”