An adaptable dual species effusive source and Zeeman slower design demonstrated with Rb and Li

Abstract

We present a dual-species effusive source and Zeeman slower designed to produce slow atomic beams of two elements with a large mass difference and with very different oven temperature requirements. We demonstrate this design for the case of 6 Li and 85 Rb and achieve magneto-optical trap (MOT) loading rates equivalent to that reported in prior work on dual species (Rb+Li) Zeeman slowers operating at the same oven temperatures. Key design choices, including thermally separating the effusive sources and using a segmented coil design to enable computer control of the magnetic field profile, ensure that the apparatus can be easily modified to slow other atomic species. By performing the final slowing using the quadrupole magnetic field of the MOT, we are able to shorten our Zeeman slower length making for a more compact system without compromising performance. We outline the construction and analyze the emission properties of our effusive sources. We also verify the performance of the source and slower, and we observe sequential loading rates of 8 × 10 8 atoms/s for a Rb oven temperature of 120 • C and 1.5 × 10 8 atoms/s for a Li reservoir at 450• C, corresponding to reservoir lifetimes for continuous operation of 10 and 4 years respectively.The ability to trap and cool multiple atomic species has garnered much interest within the cold atom community because the complex interactions within these systems give rise to a diverse range of physical phenomena., and Bose-Bose [7-9] gases allow for the study of novel states of matter which cannot be investigated in single species experiments. In particular, mixtures with large mass ratios, like those species presented here, are of interest for many body physics in the study of superfluidity [10], spin impurities, and Effimov physics [11]. Unfortunately, large mass differences also results in practical challenges when trying to slow multiple species.Abundant samples of cold atoms are also a prerequisite for the formation of ultracold hetero-nuclear molecules [12][13][14] whose long range dipole-dipole interactions lead to exotic phases of matter and possible quantum information applications [15][16][17]. LiRb is an excellent candidate for such studies as it is predicted to have the second largest electric inherent dipole moment of the alkali dimers and when in the triplet state has the added advantage of a magnetic dipole moment [18]. Furthermore, for certain experiments, there are practical advantages to having the ability to trap multiple species. For example, one species with poor collisional properties (which limit the efficacy of evaporative cooling) can be cooled sympathetically via interactions with the other species [19][20][21][22]. In other cases, one species can serve as an atomic detector to measure properties of the system, as has been demonstrated for thermodynamic measurements [23,24].Creating large samples of cold atoms while still maintaining a good vacuum in the trapping region can be achieved by creating an atomic beam with an effusive oven separated from ...

A versatile dual-species Zeeman slower for caesium and ytterbium

“…2 each have pros and cons. 39,40,44,47,49 A design with a small exit magnetic field B 0 ⇠ 0, as in the top row of Fig. 2, allows the exit field to be smoothly connected into the relatively small field gradient of the MOT and the associated small detuning ⇠ 0 can be easily produced with AOMs.…”

“…2, allows the exit field to be smoothly connected into the relatively small field gradient of the MOT and the associated small detuning ⇠ 0 can be easily produced with AOMs. 47,49 However, the Zeeman laser is then close to resonance with the atoms trapped in the MOT and, as the Zeeman laser unavoidably passes through the MOT region, this would exert a strong scattering (pushing) force on MOT. Thus, in such designs the equilibrium position and other properties of the MOT are strongly dependent on the Zeeman laser, which may be an undesirable complication.…”

“…The Doppler shift of the laser frequency, which changes as the atom decelerates, is compensated by the Zeeman shift induced by a tailored magnetic field. Zeeman slowing of a single species has been an important tool [38][39][40][41][42][43][44][45][46][47][48][49] for the field of ultracold atom trapping, typically enabling the collection in a few seconds of around 10 9 atoms in a MOT.…”

“…When two species are required, it is convenient to slow them in the same "dual-species" Zeeman decelerator 32,45,47,49,50 as this both saves space and avoids duplication of equipment. However, if the two species have significantly di↵erent properties as is the case for Cs and Yb (see Table I), this requires careful design.…”

Collimated dual species oven source and its characterisation via spatially resolved fluorescence spectroscopy

“…A high degree of collimation is in general desirable in a beam source, as this allows the required axial beam brightness to be achieved with a lower total emission rate. This improves the lifetime of the source, helps to maintain a lower background pressure in the vacuum system during source operation, and reduces the likelihood of chemically aggressive species damaging other components of the vacuum system -for example caesium exposure can degrade ion pumps and high vacuum pressure gauges, while lithium will corrode copper gaskets [7].…”