Ultracold Dipolar Molecules


Artistic rendition of ultracold molecules

(credit: Jose-Luis Olivares/MIT)

Dipolar interaction between molecules

Dipolar molecules under a microscope

Prepared at nano-Kelvin (nK) temperatures in a pristine, ultrahigh vacuum environment, ultracold atomic gases have become a wonderful testbed to explore novel quantum phenomena. The immense tunability these systems offer, together with the precision tools that atomic physics provides, has led to hallmark advances in quantum physics, ranging from the observation of Bose-Einstein condensates and strongly interacting Fermi superfluids to the quantum simulation of challenging condensed matter Hamiltonians.


However, experiments with neutral atoms have an important limitation in that the underlying interaction between a pair of atoms is a simple contact interaction – essentially, a quantum mechanical version of collisions between a pair of billiard balls. In contrast, molecules that have stable electric dipole moments in their electronic ground state experience strong dipole-dipole interaction that is long-range and spatially anisotropic. In the quantum regime, these molecules are predicted to give access to a host of exciting opportunities such as realizing exotic topological superfluids and quantum crystals and performing the quantum simulation of extended Hubbard models and spin Hamiltonians that require long-range interactions.

Our current research focus is to create a quantum gas of strongly dipolar molecules in a versatile experimental setup that combines state-of-the-art optical trapping and imaging techniques. By incorporating a high-resolution imaging objective, we aim to explore the many-body states of this system with single-site imaging resolution of molecules in the presence of an optical lattice. Furthermore, a regular array of these molecules will be a starting point to construct a highly scalable processor for quantum computing, where the rich manifold of molecular internal states will allow the robust storage of quantum information and the strong dipolar interaction will allow processing of information.

Other Research Interests: Strongly Interacting Fermi Gases

Strongly interacting atomic Fermi gases realize an effective spin-1/2 system whose interspin interaction strength can be arbitrarily and precisely tuned. Using what is known as a "Feshbach resonance," the scattering length between the spin-up and -down atoms can be tuned from positive (repulsive) to negative (attractive) values, and can even be made to diverge (unitarity). At sufficiently low temperatures, in each of these interaction regimes, the atoms pair up and condense to form a superfluid, whose microscopic description smoothly crosses over from that of a BEC of bosonic molecules to that of a BCS superfluid of Cooper pairs in momentum space. At unitarity, where the scattering length has diverged, a novel form of interaction-driven high-temperature superfluidity is realized, whose scale-invariant nature provides connections to other exotic states of matter such as those found in neutron stars and quark-gluon plasmas.