Orders-of-magnitude improvement in precision spectroscopy of an inner-shell orbital clock transition in neutral ytterbium

TL;DR

This paper reports nearly two orders of magnitude improvement in the precision of an inner-shell orbital clock transition in neutral ytterbium, enabling advanced physics tests and quantum science applications.

Contribution

The authors achieved unprecedented precision in spectroscopy of the ytterbium clock transition using a 3D optical lattice, observing coherent dynamics and isotope shifts with sub-10 Hz accuracy.

Findings

Two-orders-of-magnitude improvement in transition precision

Observation of coherent Rabi oscillations and Feshbach resonance

Set bounds on hypothetical boson-mediated forces

Abstract

An inner-shell orbital clock transition $^1S_0 \leftrightarrow 4f^{13}5d6s^2 \: (J=2)$ in neutral ytterbium atoms has attracted much attention as a new optical frequency standard as well as a highly sensitive probe for several new physics phenomena, such as ultralight dark matter, violation of local Lorentz invariance, and a new Yukawa potential between electrons and neutrons. Here, we demonstrate almost two-orders-of-magnitude improvement in precision spectroscopy over the previous reports on this transition, achieved by trapping atoms in a three-dimensional magic-wavelength optical lattice. In particular, we successfully observe the coherent Rabi oscillation, the relaxation dynamics of the excited state and the interorbital Feshbach resonance. To highlight the high precision of our spectroscopy, we carry out precise isotope shift measurements between five stable bosonic isotopes well below 10 Hz uncertainties, successfully setting bounds for a hypothetical boson mediating a force between electrons and neutrons. These results open up the way for various new physics search experiments and a wide range of applications to quantum science with this clock transition.