title: Matter wave lensing to picokelvin temperatures.
abstract: Using a matter wave lens and a long time of flight, we cool an ensemble of ^{87}Rb atoms in two dimensions to an effective temperature of less than 50_{-30}^{+50}  pK. A short pulse of red-detuned light generates an optical dipole force that collimates the ensemble. We also report a three-dimensional magnetic lens that substantially reduces the chemical potential of evaporatively cooled ensembles with a high atom number. By observing such low temperatures, we set limits on proposed modifications to quantum mechanics in the macroscopic regime. These cooling techniques yield bright, collimated sources for precision atom interferometry.
authors.affiliation: Department of Physics, Stanford University, Stanford, California 94305, USA.
authors.forename: Tim
authors.initials: T
authors.lastname: Kovachy
authors.affiliation: Department of Physics, Stanford University, Stanford, California 94305, USA.
authors.forename: Jason M
authors.initials: JM
authors.lastname: Hogan
authors.affiliation: Department of Physics, Stanford University, Stanford, California 94305, USA.
authors.forename: Alex
authors.initials: A
authors.lastname: Sugarbaker
authors.affiliation: Department of Physics, Stanford University, Stanford, California 94305, USA.
authors.forename: Susannah M
authors.initials: SM
authors.lastname: Dickerson
authors.affiliation: Department of Physics, Stanford University, Stanford, California 94305, USA.
authors.forename: Christine A
authors.initials: CA
authors.lastname: Donnelly
authors.affiliation: Department of Physics, Stanford University, Stanford, California 94305, USA.
authors.forename: Chris
authors.initials: C
authors.lastname: Overstreet
authors.affiliation: Department of Physics, Stanford University, Stanford, California 94305, USA.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Kasevich