The metastable Q 3 Δ 2 state of ThO: a new resource for the ACME electron EDM search
Abstract

The best upper limit for the electron electric dipole moment was recently set by the ACME collaboration. This experiment measures an electron spin-precession in a cold beam of ThO molecules in their metastable$H(3Δ1)$state. Improvement in the statistical and systematic uncertainties is possible with more efficient use of molecules from the source and better magnetometry in the experiment, respectively. Here, we report measurements of several relevant properties of the long-lived$Q(3Δ2)$state of ThO, and show that this state is a very useful resource for both these purposes. TheQstate lifetime is long enough that its decay during the time of flight in the ACME beam experiment is negligible. The large electric dipole moment measured for theQstate, giving rise to a large linear Stark shift, is ideal for an electrostatic lens that increases the fraction of molecules detected downstream. The measured magnetic moment of theQstate is also large enough to be used as a sensitive co-magnetometer in ACME. Finally, we show that theQstate has a large transition dipole moment to the$C(1Π1)$state, which allows for efficient population transfer between the ground stateand theQstate via$X−C−Q$Stimulated Raman Adiabatic Passage (STIRAP). We demonstrate 90 % STIRAP transfer efficiency. In the course of these measurements, we also determine the magnetic moment ofCstate, the$X→C$transition dipole moment, and branching ratios of decays from theCstate.

Authors:
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Award ID(s):
Publication Date:
NSF-PAR ID:
10303201
Journal Name:
New Journal of Physics
Volume:
22
Issue:
2
Page Range or eLocation-ID:
Article No. 023013
ISSN:
1367-2630
Publisher:
IOP Publishing
National Science Foundation
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