Magnetic and electric dipole moments of the $H\ {}^3\Delta_1$ state in ThO

TL;DR

This paper measures the magnetic and electric dipole moments of the $H^3 riangle_1$ state in ThO, providing critical parameters for improving the sensitivity and systematic control in electron EDM experiments.

Contribution

The paper provides the first precise measurements of the magnetic and electric dipole moments of the ThO $H^3 riangle_1$ state, essential for electron EDM searches.

Findings

Magnetic dipole moment $oldsymbol{ extmu_H = 8.5(5) imes 10^{-3} oldsymbol{ extmu_B}}$ shows predicted cancellation effects.

Electric dipole moment is fully saturated at electric fields below 10 V/cm.

Results help suppress systematic errors in eEDM measurement experiments.

Abstract

The metastable $H \ {}^3\Delta_1$ state in the thorium monoxide (ThO) molecule is highly sensitive to the presence of a CP-violating permanent electric dipole moment of the electron (eEDM). The magnetic dipole moment $\mu_H$ and the molecule-fixed electric dipole moment $D_H$ of this state are measured in preparation for a search for the eEDM. The small magnetic moment $\mu_H = 8.5(5) \times 10^{-3} \ \mu_B$ displays the predicted cancellation of spin and orbital contributions in a ${}^3 \Delta_1$ paramagnetic molecular state, providing a significant advantage for the suppression of magnetic field noise and related systematic effects in the eEDM search. In addition, the induced electric dipole moment is shown to be fully saturated in very modest electric fields ($<$ 10 V/cm). This feature is favorable for the suppression of many other potential systematic errors in the ThO eEDM search experiment.