Enhanced observation time of magneto-optical traps using micro-machined non-evaporable getter pumps

Abstract

We show that micro-machined non-evaporable getter pumps (NEGs) can extend the time over which laser cooled atoms can be produced in a magneto-optical trap (MOT), in the absence of other vacuum pumping mechanisms. In a first study, we incorporate a silicon-glass microfabricated ultra-high vacuum (UHV) cell with silicon etched NEG cavities and alumino–silicate glass (ASG) windows and demonstrate the observation of a repeatedly-loading MOT over a 10 min period with a single laser-activated NEG. In a second study, the capacity of passive pumping with laser activated NEG materials is further investigated in a borosilicate glass-blown cuvette cell containing five NEG tablets. In this cell, the MOT remained visible for over 4 days without any external active pumping system. This MOT observation time exceeds the one obtained in the no-NEG scenario by almost five orders of magnitude. The cell scalability and potential vacuum longevity made possible with NEG materials may enable in the future the development of miniaturized cold-atom instruments.

A simple imaging solution for chip-scale laser cooling

“…However, the increased hole diameter aids an improved numerical aperture, also plotted in Fig. 2 (b) for a MOT position of 2 mm above the grating surface, such that a larger hole diameter is favourable for imaging with the small atom numbers that have been observed in passively pumped vacuum cells 26 . Taking this into account, a 3 mm hole diameter was selected for through-hole imaging.…”

“…While extracting atom number with the through-hole system, fluorescence measurements from the MOT loading curves were simultaneously measured using a separate detection telescope with a spatially selective focal plane (described in Ref. 26 ) at an angle of around 30°to the grating surface (not shown in Fig. 1).…”

“…Additionally, a steeper angle of diffraction with a two-dimensional grating geometry would provide an overlap volume that is largest at the chip surface for an improved atom number within the reduced vacuum volume compared to the tri-segmented chip used here. The improved atom number will enable studies into passive pumping with NEGs in an aluminosilicate based chip-scale cell 26 .…”

A passively pumped vacuum package sustaining cold atoms for more than 200 days

“…[13] While efforts are being made by others to miniaturize vacuum systems for the purpose of atomic sensors, [7,8,14] to our knowledge this is the first demonstration of a passively pumped chamber sustaining a MOT for more than a week. [15] The primary challenge of the design is to make a chamber that can sustain a high level of vacuum without dependence on active pumping, such as an ion pump, while allowing the optical access needed for cold atom experiments. We utilize non-evaporable getters, which passively pump the chamber by means of chemisorption.…”

Stand-alone vacuum cell for compact ultracold quantum technologies

“…Custom components have been required to improve on the vacuum system SWaP, leading to vacuum seal challenges, particularly when including the necessary optical access. Ideally the system would be passively pumped 24,29 , to eradicate vacuum power requirements. The resulting finite vacuum lifetime could be maximised by careful choice of materials to minimise outgassing and the permeation of non-pumpable noble gases 25,30 .…”