Matt Grau

Precision Spectroscopy of Polarized Molecules in an Ion Trap

Toward a New Physics The search for physics beyond the Standard Model is carried out at accelerator facilities such as the Large Hadron Collider but also on a smaller scale in atomic and molecular physics experiments. One of the signatures of this “new physics” would be a nonvanishing electric dipole moment of the electron, but experiments designed to look for it need to distinguish between the signal and many potential artifacts. Loh et al. (p. 1220) introduce a method based on the spectroscopy of polarized molecular ions that avoids some of the sources of systematic error. A method to measure the electric dipole moment of the electron is demonstrated by using polarized trapped molecular ions. Polar molecules are desirable systems for quantum simulations and cold chemistry. Molecular ions are easily trapped, but a bias electric field applied to polarize them tends to accelerate them out of the trap. We present a general solution to this issue by rotating the bias field slowly enough for the molecular polarization axis to follow but rapidly enough for the ions to stay trapped. We demonstrate Ramsey spectroscopy between Stark-Zeeman sublevels in 180Hf19F+ with a coherence time of 100 milliseconds. Frequency shifts arising from well-controlled topological (Berry) phases are used to determine magnetic g factors. The rotating-bias-field technique may enable using trapped polar molecules for precision measurement and quantum information science, including the search for an electron electric dipole moment.

Laser-induced fluorescence studies of HfF+ produced by autoionization

Autoionization of Rydberg states of HfF, prepared using the optical-optical double resonance technique, holds promise to create HfF(+) in a particular Zeeman level of a rovibronic state for an electron electric dipole moment search. We characterize a vibronic band of Rydberg HfF at 54 cm(-1) above the lowest ionization threshold and directly probe the state of the ions formed from this vibronic band by performing laser-induced fluorescence on the ions. The Rydberg HfF molecules show a propensity to decay into only a few ion rotational states of a given parity and are found to preserve their orientation qualitatively upon autoionization. We show empirically that we can create 30% of the total ion yield in a particular ∣J(+), M(+) state and present a simplified model describing autoionization from a given Rydberg state that assumes no angular dynamics.

Progress of the JILA Electron EDM Experiment

Author Institution: JILA, National Institute of Standards and Technology and University of Colorado Department of Physics, University of Colorado, Boulder, Colorado 80309-0440, USA

PRECISION SPECTROSCOPY OF TRAPPED HfF+ WITH A COHERENCE TIME OF 1 SECOND

Trapped molecular ions provide new systems for precision spectroscopy and tests of fundamental physics. For example, measurements of the permanent electric dipole moment of the electron (eEDM) test time-reversal symmetrya. Currently, we are using Ramsey spectroscopy between spin states of the metastable ∆1 state in trapped HfF for a measurement of the eEDMb,c. We are regularly performing spectroscopy with a Ramsey time of 500 ms yielding what, to our knowledge, is the narrowest spectral line observed in a molecular system. Here, we will provide an overview of the experiment and the current eEDM results.