Precision measurements with an ultracold molecular clock

Andrew T. Grier, Mickey McDonald, B. H. McGuyer +4 more

Chih-Hsi Lee, Stanimir Kondov, Christian Liedl +2 more

Tanya Zelevinsky

Abstract : We have established the strontium molecular clock as the leading ultracold-molecule precision measurement platform. We can fully control the molecules internal and external quantum states, as in state-of-the-art atomic lattice clocks. Using the quantized molecular spectra in an optical lattice, we devised a new lattice thermometry method that is advantageous for many lattice experiments, including clocks and manybody physics studies. The full quantum control allowed us to observe deeply subradiant molecular states, and coherently control them. We measured lifetimes enhanced by up to 300 times. Ultranarrow transitions to these states permitted a rigorous study of asymptotic physics at the atom-molecule threshold. We proved that subradiant states can decay to the ground state via higher-order electromagnetic transitions, with a rate that grows as the square of the bond length, and are quenched by predissociation at a rate proportional to the vibrational level spacing. We introduced a precise technique for measuring molecular binding energies via photofragmentation; controlled forbidden optical transition strengths with weak magnetic fields by five orders of magnitude; and explained anomalously large magnetic susceptibilities of the asymptotic molecules. The unprecedented precision, coupled with advanced ab initio theory, paves the way to exciting new directions for the molecular clock.

Jun Ye, Sebastian Blatt, Martin M. Boyd +8 more

Xibo Zhang, Jun Ye

Abstract Precision measurement and frequency metrology have pushed many scientific and technological frontiers in the field of atomic, molecular and optical physics. In this article, we provide a brief review on the recent development of optical atomic clocks, with an emphasis placed on the important inter-dependence between measurement precision and systematic effects. After presenting a general discussion on the motivation and techniques behind the development of optical lattice clocks, where the use of many atoms greatly enhances the measurement precision, we present the JILA strontium optical lattice clock as the leading system of frequency metrology with the lowest total uncertainty, and we describe other related research activities. We discuss key ingredients that have enabled the optical lattice clocks with ultracold atoms to reach the 18th digit in both precision and accuracy. Furthermore, we discuss extending the power of precision clock spectroscopy to study quantum many-body physics and to provide control for atomic quantum materials. In addition, we explore future research directions that have the potential to achieve even greater precision.

Mateusz Borkowski

Abstract With relative accuracies reaching 10−18, optical atomic clocks are currently the most sensitive physical instruments known to man. Weakly bound ultracold molecules enable the study of fundamental physics through their sensitivity to e.g. the proton-to-electron mass ratio or hypothetical Yukawa-type fifth forces predicted by several extensions of the Standard Model. These applications, however, require precision measurements of molecular transitions that are beyond current experimental capabilities. Here we propose to construct an ‘optical molecular clock’ that would solve this problem by bringing the experimental techniques used in optical atomic clocks to the realm of cold molecules. We show that such a clock could utilize ultracold ytterbium molecules and we predict the positions and properties of Yb2 clock lines. A successful experimental realization of this proposal could pave the way towards sub-Hz level molecular spectroscopy.