Systematic optimization of laser cooling of dysprosium

Abstract

We report on an apparatus for cooling and trapping of neutral dysprosium. We characterize and optimize the performance of our Zeeman slower and 2D molasses cooling of the atomic beam by means of Doppler spectroscopy on a 136 kHz broad transition at 626 nm. Furthermore, we demonstrate the characterization and optimization procedure for the loading phase of a magneto-optical trap (MOT) by increasing the effective laser linewidth by sideband modulation. After optimization of the MOT compression phase, we cool and trap up to 10 9 atoms within 3 seconds in the MOT at temperatures of 9 µK and phase space densities of 1.7·10 −5 , which constitutes an ideal starting point for loading the atoms into an optical dipole trap and for subsequent forced evaporative cooling.

Enhancing the capture velocity of a Dy magneto-optical trap with two-stage slowing

“…Due to the recent explosion in popularity of dysprosium, several groups have developed similar cooling and trapping protocols in parallel [2][3][4][5][6]13]. Here we briefly describe our approach and give references to more detailed explanations of similar systems.…”

“…Dysprosium, which possesses the largest magnetic moment (μ ≈ 10μ B ) of any atomic species, has grown in popularity in the ultracold quantum gas community over the last decade [1][2][3][4][5][6][7][8][9][10][11]. The large magnetic moment, as well as several other useful properties, arises from its [Xe] 4 f 10 6s 2 electronic configuration.…”

“…Slowing an atomic beam to within a low capture velocity can lead to a situation where the slowed beam transversely spreads out so much that many slowed atoms miss the MOT. Cooling the transverse degrees of freedom of the atomic beam and increasing the capture velocity of the MOT by frequency dithering the MOT light are two measures which are typically employed to mitigate this limitation [2][3][4][5][6]13], but their effectiveness can be limited.…”

Spectroscopy of the 1001-nm transition in atomic dysprosium

“…A magneto-optical trap (MOT) operated on the Γ 626 = 2π × 136 kHz transition from the ground-state at 626 nm is loaded from a Zeeman slower, which is using the Γ 421 = 2π × 32 MHz broad 421 nm transition. Details of the experimental setup can be found in [15]. Typically, 3 · 10 6 162 Dy or 164 Dy atoms or 3 · 10 5 160 Dy atoms arXiv:1907.05754v2 [physics.atom-ph] 10 Sep 2019 are trapped and cooled to temperatures on the order of 30 µK.…”

Sawtooth-wave adiabatic-passage slowing of dysprosium

“…2(a). A continuous beam of decelerated Dy atoms leaves a Zeeman slower (ZS) described in [25]. The atoms have a typical velocity distribution featuring a peak at about 20 m/s and a tail extending to even negative velocities as shown in Fig.…”