Precision Photodissociation: a New Tool for Ultracold Chemistry and Physics, and a Source of Novel Quantum Gases
Abstract
Precision Photodissociation:A New Tool for Ultracold Chemistry and Physics, and a Source of Novel Quantum GasesWe propose to harness a new observable associated with ultracold molecular gases in opticallattices, which consists of the angular distribution of atomic fragments that are produced duringphotodissociation (light-induced fragmentation) of diatomic molecules. In the course of thisproject, we will fully develop quantum-state-selected photodissociation and apply it to molecularmetrology and to creation of novel quantum gases. We have shown that for molecules trapped inan optical lattice, an extremely high degree of quantum state control can be achieved, leading toproduction of highly nonclassical continuum states of the fragments, with complicated angulardistributions. These distributions are consistent with quantum mechanics, but generally fail thequasiclassical description which has been used for essentially all photodissociation experimentsto date. A central objective for our project is to develop and advance the technique of imagingphotofragment angular distributions and thus obtain a new handle on controlling basic molecularreactions. Specifically, we will demonstrate control of photodissociation with weak magneticfields, - such field control of molecular bond breaking processes at the quantum level is animportant theme in the field of ultracold chemistry, but so far has been difficult to implement.We will also use applied fields to control matter-wave interference between photodissociationproducts, and to characterize the previously unobserved transition of ultracold chemistry fromthe quantum to the quasiclassical regime. An important consequence of dissociating moleculesin an optical lattice is the extreme control of the external degrees of freedom, i.e. of the fragmentenergies. We are able to break molecular bonds with excess heating at only the nanokelvin level,which inspires us to proceed in two directions. Firstly, with lattice-trapped molecules we cancarry out the most precise spectroscopic study to-date of the van der Waals interatomicinteraction, leading to a much deeper understanding of this diatomic molecular bond. This is ahigh-precision metrological measurement, since the experimental configuration is that of a~molecular lattice clock~ which could be competitive with but complementary to an atomiclattice clock. Secondly, dissociation with extremely low excess energy suggests the possibilityof breaking apart laser-cooled diatomic molecules into their exotic atomic constituents andobtaining previously inaccessible dilute ultracold atomic gases. We have constructed an initialsetup to attempt this with barium hydride diatomic molecules, and will develop the technologyfurther during this project. The proposed work is based on a successful ONR funded project inour laboratory, and is directly in line with many stated ONR interests in quantum control ofmolecules, metrology with trapped molecules, and development of new techniques andobservables for ultracold physics and chemistry. The ONR goals of improving timekeeping andsensing will be advanced by the state-of-the-art control of molecular quantum states.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 03, 2017
- Source ID
- N000141712246
Entities
People
- Tanya Zelevinsky
Organizations
- Office of Naval Research
- Trustees of Columbia University in the City of New York
- United States Navy