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

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 metastableH(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-livedQ(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 theC(1Π1)state, which allows for efficient population transfer between the ground stateXmore » width='0.50em'/>(1Σ+)and theQstate viaXCQStimulated Raman Adiabatic Passage (STIRAP). We demonstrate 90 % STIRAP transfer efficiency. In the course of these measurements, we also determine the magnetic moment ofCstate, theXCtransition dipole moment, and branching ratios of decays from theCstate.

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Award ID(s):
1734011 1912513
Publication Date:
Journal Name:
New Journal of Physics
Page Range or eLocation-ID:
Article No. 023013
IOP Publishing
Sponsoring Org:
National Science Foundation
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