EDM Ion Trap


Current Members

Dan Gresh, Will Cairncross, Tanya Roussy, Yuval Shagam, Fatemeh Abbasi Razgaleh, Yan Zhou, Jun Ye, and Eric Cornell


Will Cairncross, Yuval Shagam, Fatemeh Abbasi Razgaleh, Kia Boon Ng, Tanya Roussy, and Dan Gresh.


An electron EDM search using trapped molecular ions


The JILA electron EDM experiment (eEDM) uses the unique approach of performing a high-precision measurement on HfF+ molecular ions trapped in an rf trap. A low-lying, metastable 3Δ1 state in HfF+ with a 2.1(1) s radiative lifetime offers enhanced eEDM sensitivity, rejection of systematic errors, and measurement coherence times of greater than 1 s. Additionally, the ability to explicitly measure phase at early and late spin precession times provides suppression of systematic errors common to beamline experiments.

Our recently-concluded first-generation experiment has placed a limit on the eEDM of |d_e| < 1.3 x 10-28 e cm. The second-generation experiment will use an optimized ion trap with a greater electric field uniformity, a larger electric field amplitude, and a larger trapping volume, to extend the measurement coherence time and the count rate. ThF+, with a larger internal effective electric field and a 3Δ1 ground state, is a candidate to replace HfF+ for a third-generation eEDM experiment.

Selected Paper Abstracts

A precision measurement of the electron’s electric dipole moment using trapped molecular ions

We describe the first precision measurement of the electron’s electric dipole moment (eEDM, de) using trapped molecular ions, demonstrating the application of spin interrogation times over 700 ms to achieve high sensitivity and stringent rejection of systematic errors. Through electron spin resonance spectroscopy on 180Hf19F+ in its metastable 3∆1 electronic state, we obtain de = (0.9 ± 7.7stat ± 1.7syst ) × 10−29 e cm, resulting in an upper bound of |de| < 1.3 × 10−28 e cm (90% confidence). Our result provides independent confirmation of the current upper bound of |de| < 9.3 × 10−29 e cm [J. Baron et al., Science 343, 269 (2014)], and offers the potential to improve on this limit in the near future.

Submitted. arXiv

Precision Spectroscopy of Polarized Molecules in an Ion Trap

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 ms. 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.

Science 342, 1220-1222 (2013). arXiv

Broadband velocity modulation spectroscopy of HfF+: Towards a measurement of the electron electric dipole moment

Precision spectroscopy of trapped HfF^+ will be used in a search for the permanent electric dipole moment of the electron (eEDM). While this dipole moment has yet to be observed, various extensions to the standard model of particle physics (such as supersymmetry) predict values that are close to the current limit. We present extensive survey spectroscopy of 19 bands covering nearly 5000 cm^(-1) using both frequency-comb and single-frequency laser velocity-modulation spectroscopy. We obtain high-precision rovibrational constants for eight electronic states including those that will be necessary for state preparation and readout in an actual eEDM experiment.

Chem. Phys. Lett. 546, (2012) 1-11. arXiv

High-resolution spectroscopy on trapped molecular ions in rotating electric fields: A new approach for measuring the electron electric dipole moment

High-resolution molecular spectroscopy is a sensitive probe for violations of fundamental symmetries. Symmetry violation searches often require, or are enhanced by, the application of an electric field to the system under investigation. This typically precludes the study of molecular ions due to their inherent acceleration under these conditions. Circumventing this problem would be of great benefit to the high-resolution molecular spectroscopy community since ions allow for simple trapping and long interrogation times, two desirable qualities for precision measurements. Our proposed solution is to apply an electric field that rotates at radio frequencies. We discuss considerations for experimental design as well as challenges in performing precision spectroscopic measurements in rapidly time-varying electric fields. Ongoing molecular spectroscopy work that could benefit from our approach is summarized. In particular, we detail how spectroscopy on a trapped diatomic molecular ion with a ground or metastable 3Δ1 level could prove to be a sensitive probe for a permanent electron electric dipole moment (eEDM).

J. Mol. Spectrosc. 270 (2011) 1-25. arXiv