Sawtooth-wave adiabatic-passage slowing of dysprosium

Abstract

We report on sawtooth wave adiabatic passage (SWAP) slowing of bosonic and fermionic dysprosium isotopes by using a 136 kHz wide transition at 626 nm. A beam of precooled atoms is further decelerated in one dimension by the SWAP force and the amount of atoms at near zero velocity is measured. We demonstrate that the SWAP slowing can be twice as fast as in a conventional optical molasses operated on the same transition. In addition, we investigate the parameter range for which the SWAP force is efficiently usable in our set-up, and relate the results to the adiabaticity condition. Furthermore, we add losses to the hyperfine ground-state population of fermionic dysprosium during deceleration and observe more robust slowing with SWAP compared to slowing with the radiation pressure force.

Simulations of sawtooth-wave adiabatic passage with losses

“…As was found in Refs. [5][6][7][8][9], SWAP cooling does not achieve a temperature as low as that from Doppler cooling; for the range plotted in Fig. 1, the asymptotic temperature was more than ∼ 10X the Doppler temperature for ev- eryω r .…”

“…Finally, as was seen in Refs. [5][6][7][8][9], the simulations showed that the kinetic energy is extracted from the atom much faster using SWAP than using Doppler cooling.…”

“…Reference [6] described in more detail the simple theoretical model for this process and presented the results from several simulations. Reference [7] performed SWAP cooling of Dy using a transition at 626 nm with a 136 kHz linewidth. This transition is ∼ 20× broader than that in the demonstration on Sr. Reference [8] described experimental results for SWAP cooling of Sr in a magnetooptical trap.…”

Laser cooling with adiabatic transfer on a Raman transition

“…Recently, a new mechanism called Sawtooth Wave Adiabatic Passage (SWAP) cooling was observed using a narrow-linewidth optical transition in 88 Sr atoms [25], and a related deflection force was previously reported in He atoms [26]. The SWAP technique has now been used for slowing Dy [27] and for creating faster, denser Sr magneto-optical traps (MOTs) [28,29]. The forces that give rise to SWAP cooling rely on adiabatic transitions back and forth between a ground state añ | and a long-lived optically excited state bñ | with lifetime τ=1/Γ.…”

Laser cooling using adiabatic rapid passage

“…Recently, a sawtooth-wave adiabatic passage (SWAP) scheme was demonstrated to cool atoms by rapidly sweeping the laser frequency of counter-propagating beams with Doppler shifts providing time-ordering to ensure photon recoils oppose the particle's motion [7][8][9]. This technique, when adopted to more complex multi-level systems, is shown to be resultative for cooling molecules [10]. The enhancement of the cooling force was achieved by applying a proper magnetic field decomposing the multi-level system into several two-level systems to provide an ordered stimulated absorption and emission allowing for a multiple photon momentum transfer.…”