S. Aubin

A single hollow-beam optical trap for cold atoms

We present an optical trap for atoms which we have developed for precision spectroscopy measurements. Cold atoms are captured in a dark region of space inside a blue-detuned hollow laser beam formed by an axicon. We analyse the light potential in a ray optics picture and experimentally demonstrate trapping of laser-cooled metastable xenon atoms.

Quantum Pumping with Ultracold Atoms on Microchips: Fermions versus Bosons

We present a design for simulating quantum pumping of electrons in a mesoscopic circuit with ultracold atoms in a micromagnetic chip trap. We calculate theoretical results for quantum pumping of both bosons and fermions, identifying differences and common features, including geometric behavior and resonance transmission. We analyze the feasibility of experiments with bosonic ;{87}Rb and fermionic ;{40}K atoms with an emphasis on reliable atomic current measurements.

Dual‐Species Quantum Degeneracy of 40K and 87Rb on an Atom Chip

In this article we review our recent experiments with a 40K‐87Rb mixture. We demonstrate rapid sympathetic cooling of a 40K‐87Rb mixture to dual quantum degeneracy on an atom chip. We also provide details on efficient BEC production, species‐selective magnetic confinement, and progress toward integration of an optical lattice with an atom chip. The efficiency of our evaporation allows us to reach dual degeneracy after just 6 s of evaporation ‐ more rapidly than in conventional magnetic traps. When optimizing evaporative cooling for efficient evaporation of 87Rb alone we achieve BEC after just 4 s of evaporation and an 8 s total cycle time.

Lifetime and hyperfine splitting measurements on the 7s and 6p levels in rubidium

We present lifetime measurements of the 7S1/2 level and the 6p manifold of rubidium. We use a time-correlated single-photon counting technique on a sample of 85Rb atoms confined and cooled in a magneto-optic trap. The upper state of the 5P1/2 repumping transition serves as the resonant intermediate level for two-photon excitation of the 7s level. A probe laser provides the second step of the excitation, and we detect the decay of atomic fluorescence to the 5P3/2 level at 741 nm. The decay process feeds the 6p manifold that decays to the 5s ground state emitting UV photons. We measure lifetimes of 88.07±0.40 and 120.7±1.2 ns for the 7S1/2 level and 6p manifold, respectively; the hyperfine splitting of the 7S1/2 level is 282.6±1.6 MHz. The agreement with theoretical calculations confirms the understanding of the wave functions involved and provides confidence on the possibility of extracting weak interaction constants from a parity nonconservation measurement.

Commissioning of the Francium Trapping Facility at TRIUMF

We report on the successful commissioning of the Francium Trapping Facility at TRIUMF. Large laser-cooled samples of francium are produced from a francium ion beam delivered by the ISAC radioactive ion beam facility. The ion beam is neutralized on an yttrium foil, which is subsequently heated to transfer the atoms into the magneto-optical trapping region. We have successfully trapped 207Fr, 209Fr and 221Fr, with a maximum of 2.5 × 105 209Fr atoms. The neutral cold atoms will be used in studies of the weak interaction through measurements of atomic parity non-conservation.

Note: fast, small, and low vibration mechanical laser shutters.

We present three novel mechanical laser shutter designs based, respectively, on a stepper motor, a relay, and a piezoelectric actuator. Each shutter type is ideally suited to a specific shuttering application. The stepper motor is well suited for applications requiring low vibrations, the relay is compact and capable of rapid bursts, and the piezoelectric is 2 orders of magnitude faster than other available mechanical shutters.

Atom chip apparatus for experiments with ultracold rubidium and potassium gases

We present a dual chamber atom chip apparatus for generating ultracold (87)Rb and (39)K atomic gases. The apparatus produces quasi-pure Bose-Einstein condensates of 10(4) (87)Rb atoms in an atom chip trap that features a dimple and good optical access. We have also demonstrated production of ultracold (39)K and subsequent loading into the chip trap. We describe the details of the dual chamber vacuum system, the cooling lasers, the magnetic trap, the multicoil magnetic transport system, the atom chip, and two optical dipole traps. Due in part to the use of light-induced atom desorption, the laser cooling chamber features a sufficiently good vacuum to also support optical dipole trap-based experiments. The apparatus is well suited for studies of atom-surface forces, quantum pumping and transport experiments, atom interferometry, novel chip-based traps, and studies of one-dimensional many-body systems.

The Francium facility at TRIUMF

We present the current status of the Francium Trapping Facility at ISAC at TRIUMF. The facility will enable future experiments on the weak interaction with measurements of atomic parity non-conservation laser-cooled samples of artificially produced francium. These experiments require a precisely controlled environment, which the facility is designed to provide. The facility has been constructed and is being prepared for a series of commissioning runs.

Lifetime measurement of the 9s level of atomic francium

We use two-photon resonant excitation and time-correlated single-photon counting techniques on a sample of 210Fr atoms confined and cooled in a magneto-optical trap to measure the lifetime of the 9s excited level. Direct measurement of the decay through the 7P(3/2) level at 851 nm yields a lifetime of 107.53 +/- 0.80 ns.

Scattering by an oscillating barrier: Quantum, classical, and semiclassical comparison

We present a detailed study of scattering by an amplitude-modulated potential barrier using three distinct physical frameworks: quantum, classical, and semiclassical. Classical physics gives bounds on the energy and momentum of the scattered particle, while also providing the foundation for semiclassical theory. We use the semiclassical approach to selectively add quantum-mechanical effects such as interference and diffraction. We find good agreement between the quantum and semiclassical momentum distributions. Our methods and results can be used to understand quantum and classical aspects of transport mechanisms involving time-varying potentials, such as quantum pumping.