All-optical production and trapping of metastable noble-gas atoms down to the single-atom regime

Abstract

The determination of isotope ratios of noble gas atoms has many applications e.g. in physics, nuclear arms control, and earth sciences. For several applications, the concentration of specific noble gas isotopes (e.g. Kr and Ar) is so low that single atom detection is highly desirable for a precise determination of the concentration. As an important step in this direction, we demonstrate operation of a krypton Atom Trap Trace Analysis (ATTA) setup based on a magneto-optical trap (MOT) for metastable Kr atoms excited by all-optical means. Compared to other state-of-the-art techniques for preparing metastable noble gas atoms, all-optical production is capable of overcoming limitations regarding minimal probe volume and avoiding cross-contamination of the samples. In addition, it allows for a compact and reliable setup. We identify optimal parameters of our experimental setup by employing the most abundant isotope 84 Kr, and demonstrate single atom detection within a 3D MOT.

Observation of dynamic Stark resonances in strong-field excitation

“…In recent years, there has been a demand for higher efficiency and cleaner sources of metastable atoms, encouraging all-optical methods of generation to be pursued. Examples include two-photon absorption [8] or methods employing UV lamps [9]. Strong-field excitation is also a promising technique.…”

Laser-Based Metastable Krypton Generation

“…This minimum gas density requirement means that typically the discharge source is situated some distance from the experimental chamber and a series of specialized equipment is required to extract and transport the metastable atoms [21]. Previously all-optical approaches have been shown to circumvent this pressure requirement but have so far not demonstrated an increase in efficiency [22]. Furthermore, for applications where accurate measurements of the isotopic density of a sample is being measured, the sputtering of highly charged, electro-statically accelerated noble gas ions (11-25 eV) onto the surface of the vacuum chamber can lead to slow outgassing and unwanted cross-contamination between samples [13].…”

Maximizing optical production of metastable xenon

“…Although relatively high metastable state densities (∼10 13 cm −3 ) can be achieved for short time scales using pulsed electrical discharge techniques [5][6][7], the realization of comparable long-term steady-state densities remains a significant challenge. Standard approaches include steady state RF excitation (see, for example, [17][18][19]), optical pumping techniques [20][21][22], and a recently proposed hybrid method which combines both [23,24]. In this paper, we investigate the experimental conditions needed to optimize this hybrid approach to maximize the production of metastable state densities.…”

“…Here an RF (or DC) field is applied to a gas of atoms, resulting in various collisional mechanisms that transfer population (both directly and indirectly) from |g to |m . In contrast, panel (b) shows an "all optical" approach in which resonant VUV light (typically from an external lamp) excites |g → |a [20][21][22]. Population is then optically pumped from |a → |u using a narrowband laser, and spontaneous emission then causes a transition from |u → |m .…”