Selection of state-insensitive or “magic” trapping conditions with ultracold atoms or molecules, where pairs of internal states experience identical trapping potentials, brings substantial benefits to precision measurements and quantum computing schemes. Working at such conditions could ensure that the detrimental effects of inevitable inhomogeneities across an ultracold sample are significantly reduced. However, this aspect of confinement remains unexplored for ultracold polar molecules. Here, we present means to control the ac Stark shift of rotational states of ultracold diatomic polar molecules, when subjected to both trapping laser light and an external electric field. We show that both the strength and relative orientation of the two fields influence the trapping potential. In particular, we predict “magic electric field strengths” and a “magic angle,” where the Stark shift is independent of the dc external field for certain rotational states of the molecule.

• Received 10 August 2010

DOI:https://doi.org/10.1103/PhysRevA.82.063421