[論文レビュー] A high-flux atomic strontium oven with light-driven flux modulation

Kenneth M. Hughes, J. Schelfhout+4 more|arXiv (Cornell University)|Mar 26, 2026

Cold Atom Physics and Bose-Einstein Condensates被引用数 0

ひとこと要約

The paper introduces a compact, re-entrant strontium oven with a laser-etched fused-silica nozzle and heated sapphire window, achieving high atomic flux and enabling light-driven flux modulation to extend oven lifetime.

ABSTRACT

A high-flux source of strontium atoms is required for cold atom quantum technology applications. We present a re-entrant oven design that avoids the need for any vacuum feed-throughs and has an inherent temperature gradient to guard against clogging of the nozzle. The nozzle is fabricated by micro-machining of fused silica using selective laser etching; this specialised technique is capable of making many thousands of fine microchannels and is suitable for batch production. Operating with only electrical heating, using <20W of electrical power, a total flux of $8(1) imes 10^{14}$ atoms/s is achieved at an oven temperature of 475°C, of which we estimate $1.8(2) imes 10^{13}$ atoms/s could be captured. A heated in-vacuum sapphire window grants optical access directly opposite the oven, and can be cleared of metallization without breaking vacuum. We used this optical access to modulate the flux of the atomic beam by direct illumination of the nozzle and the strontium metal with high-power laser light. Heating by laser light increased the useful flux by a factor of up to 16(3) on a timescale of 40s, and a factor of 2.5(5) on a timescale of 1s. This flux modulation serves to increase the operating lifetime of the oven. We report experimental measurements of the performance of the oven in long-term operation over many months.

研究の動機と目的

• Develop a high-flux, scalable Sr atomic oven suitable for cold-atom experiments.
• Demonstrate a nozzle made by selective laser etching of fused silica with thousands of microchannels.
• Enable flux modulation via direct laser heating to extend oven lifetime without breaking vacuum.

提案手法

• Use a three-piece stainless steel re-entrant oven with a microfabricated fused-silica nozzle containing 16,213 microchannels (d = 30 μm, β = 1/10).
• Employ a heated in-vacuum sapphire window opposite the oven to allow optical access and enable metallization reversal without breaking vacuum.
• Heat the oven electrically with cartridge heaters to set baseline flux; illuminate the nozzle and Sr metal with high-power 532 nm laser light to modulate flux.
• Characterize flux via transverse absorption spectroscopy of the 461 nm transition in 88Sr and fit to free molecular flow models to extract total and useful flux.
• Investigate the impact of heating pulse duration Δt = 1 s and Δt = 40 s on flux, pressure, and lineshape.
• Perform long-term operation tests to assess robustness and lifetime under modulation.

実験結果

リサーチクエスチョン

• RQ1 What flux levels can be achieved with the high-channel-count fused-silica nozzle at given oven temperatures?
• RQ2 How does direct laser heating modulate the atomic flux and what is the effect on chamber pressure and MOT-relevant flux?
• RQ3 Can the heated sapphire window prevent metallization and permit vacuum-compatible optical access for flux modulation and Zeeman slowing?
• RQ4 How do the observed lineshapes and fluxes compare to free molecular flow predictions at high fluxes?
• RQ5 What is the potential lifetime extension of the oven when using light-driven flux modulation?

主な発見

• Maximum baseline total flux of 8(1) × 10^14 atoms/s at T_oven = 475 C; estimated usable flux ~1.8(2) × 10^13 atoms/s.
• Flux increases with laser heating: Δt = 1 s raises total flux to 1.2(2) × 10^15 atoms/s and usable flux to 2.7(4) × 10^13 atoms/s; Δt = 40 s raises total flux to 2.7(4) × 10^15 atoms/s and usable flux to 5.6(7) × 10^13 atoms/s.
• Flux modulation can extend oven lifetime by enabling higher instantaneous flux at lower base temperatures; example cycle demonstrates lifetime increase by factors up to ~1.8 for typical cycle times.
• The heated sapphire window remains transparent (≤ 350 C window) and allows cleaning of metallization without breaking vacuum, enabling ongoing optical access.
• Evidence shows the absorbed lineshape agrees with free molecular flow predictions at lower heating, with deviations (Gaussian-like) at high temperatures and long pulses, prompting further study.
• Long-term operation validates robustness of the design across months of use.