Electron Electric Dipole Moment

A permanent electric dipole moment (EDM) of the electron would violate parity and time reversal symmetries, and is of considerable interest in elementary particle physics. The standard model prediction for the electron EDM, d_e < 10 ^-40 e . cm, is far too small to be detected by current methods. However many favored extensions of the standard model predict de within 3 orders of magnitude of the latest experimental limit d_e < 1.6 10^-27 e . cm. With 100-fold or greater improvements in sensitivity, some of thes models may be excluded, or evidence of new physics beyond the standard model may be discovered.

The experiment takes advantage of several unique properties of the metastable a(1)[ ³ Σ ₊ excited state of the PbO molecule, including closely spaced levels of opposite parity, long coherence times, and suitability for use in a vapor cell (enabling high counting rates), and anticipates a shot-noise limit in the near term of ~ 10^-29 e . cm, with an ultimate sensitivity of ~ 10^-31 e . cm.

So far we have demonstrated Zeeman quantum beats with signal sizes and collisional cross sections as expected, and shot-noise limited extraction (over the short term) of the beat frequencies. Precision measurements indicate the e- and f-members of the Λ-doublet have g-factors identical to 1 part in 10³, and are suitable to act as internal co-magnetometers. We have also applied electric fields in the vapor cell for a precision measurement of the Λ-doublet splitting via Stark beats.

Parity Non-Conservation in Nuclei

Measurements of parity-violating weak interactions associated with nuclear spin. Thes include the anapole moments of nuclei (which arise from weak interactions within the nucleus that are now poorly understood) and a fundamental coupling of the Z₀ boson. A measurement of the latter at our anticipated level of precision will be sensitive to certain types of new physics (e.g., quark substructure) at the 10 TeV scale.

Photo-association and Quantum Computing

Our ultimate goal is to develop a quantum computer with ultracold polar molecules as the qubits. These molecules will be arranged in an optical lattice array in a varying electric field and will be individually addressed by resonant microwave pulses.

Polar molecules are an excellent choice for qubits due to their strong interactions; the strength of qubit interactions is essential to the speed of a quantum computer.

To this end, we are currently in the process of developing an efficient way to produce ultracold RbCs molecules. Heteronulear molecules (such as RbCs) are known to be extremely polar. We have a two species Magneto Optical Trap (MOT) from which we photoassociate unbound atoms into molecular bound states.

Microwave trap for buffer-cooled molecules

Currently in the apparatus design and early construction stage, this project will eventually combine the techniques of buffer gas cooling and microwave trapping. We believe that this combination will lead to achievement of extremely cold and dense samples of polar molecules, with numerous benefits compared to other methods.

In our method, polar molecules are created via laser ablation inside a cryocell. The molecules then thermalize in a cold Helium buffer gas before being transported inside a static quadrupolar guide to a microwave trapping chamber. Once inside the microwave trap, the molecules are evaporatively cooled and observed.

We believe this will make it possible to trap large samples of a wide variety of polar species and then cool them down to arbitrarily low temperatures (e.g. to the temperature of Bose-Einstein condensation or Fermi degeneracy). This source would have a wide variety of applications, including improved versions of all the experiments listed above. It may also open up whole new directions in ultracold, many-body physics, since in comparison to atoms the interactions between polar molecules are extremely strong, long-range, anisotropic, and tunable with respect to both the strength and the degree of anisotropy.