title: Photodissociation of ultracold diatomic strontium molecules with quantum state control.
abstract: Chemical reactions at ultracold temperatures are expected to be dominated by quantum mechanical effects. Although progress towards ultracold chemistry has been made through atomic photoassociation, Feshbach resonances and bimolecular collisions, these approaches have been limited by imperfect quantum state selectivity. In particular, attaining complete control of the ground or excited continuum quantum states has remained a challenge. Here we achieve this control using photodissociation, an approach that encodes a wealth of information in the angular distribution of outgoing fragments. By photodissociating ultracold (88)Sr2 molecules with full control of the low-energy continuum, we access the quantum regime of ultracold chemistry, observing resonant and nonresonant barrier tunnelling, matter-wave interference of reaction products and forbidden reaction pathways. Our results illustrate the failure of the traditional quasiclassical model of photodissociation and instead are accurately described by a quantum mechanical model. The experimental ability to produce well-defined quantum continuum states at low energies will enable high-precision studies of long-range molecular potentials for which accurate quantum chemistry models are unavailable, and may serve as a source of entangled states and coherent matter waves for a wide range of experiments in quantum optics.
authors.affiliation: Department of Physics, Columbia University, 538 West 120th Street, New York, New York 10027-5255, USA.
authors.forename: M
authors.initials: M
authors.lastname: McDonald
authors.affiliation: Department of Physics, Columbia University, 538 West 120th Street, New York, New York 10027-5255, USA.
authors.forename: B H
authors.initials: BH
authors.lastname: McGuyer
authors.affiliation: Department of Physics, Columbia University, 538 West 120th Street, New York, New York 10027-5255, USA.
authors.forename: F
authors.initials: F
authors.lastname: Apfelbeck
authors.affiliation: Department of Physics, Columbia University, 538 West 120th Street, New York, New York 10027-5255, USA.
authors.forename: C-H
authors.initials: CH
authors.lastname: Lee
authors.affiliation: Quantum Chemistry Laboratory, Department of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland.
authors.forename: I
authors.initials: I
authors.lastname: Majewska
authors.affiliation: Quantum Chemistry Laboratory, Department of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland.
authors.forename: R
authors.initials: R
authors.lastname: Moszynski
authors.affiliation: Department of Physics, Columbia University, 538 West 120th Street, New York, New York 10027-5255, USA.
authors.forename: T
authors.initials: T
authors.lastname: Zelevinsky