发表机构
University of Innsbruck（因斯布鲁克大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究数值模拟了正电子素束的多普勒激光减速、冷却与囚禁，证实了在标准几何下可同时实现减速、冷却和光学囚禁，所需激光参数在当前技术可达范围内，为超冷正电子素及玻色-爱因斯坦凝聚体的制备奠定基础。
AI 中文摘要
我们数值研究了使用Surko阱产生的正电子束在二氧化硅微通道靶中产生的高速正电子素（Ps）束的激光减速、冷却与囚禁。虽然多普勒激光冷却通常能将中性原子物种冷却到毫开尔文以下的动能温度，但正电子素的快速基态湮灭以及高反冲位移与线宽之比对时序和所需激光功率提出了新的挑战性限制。早期的理论工作和首次实验已经展示了辐射压力冷却以产生前所未有的冷而稠密正电子素集合体的可行前景。我们扩展的数值研究证实了在标准多普勒冷却几何结构下，在$1^3\mathrm{S}$--$2^3\mathrm{P}$跃迁上同时减速、冷却和光学囚禁正电子素原子具有非常好的前景。包括完整的塞曼态流形，并在$2^3\mathrm{P}$--$3^3\mathrm{D}$跃迁上增加额外的横向激光，改善了时序和最终温度，从而允许在末端进行光学囚禁。在大多数原子未湮灭的时间范围内实现有效减速和囚禁所需的激光功率和几何参数，在当前技术条件下是可以实现的，即约$100\\ \mathrm{ns}$持续时间的$\mathrm{mJ}$能量脉冲。未来扩展到光学腔或空芯光纤中以集体增强冷却和囚禁，应最终能够快速制备超冷正电子素系统，作为未来超辐射激光和玻色-爱因斯坦凝聚体的基础。
英文摘要
We numerically study laser deceleration, cooling and trapping of host fast ortho-positronium (Ps) bunches as produced in silica microchannel targets using positron bunches from a Surko trap. While Doppler laser cooling routinely allows to cool neutral atom species below milli-Kelvin kinetic temperatures, the fast ground state annihilation and the high recoil shift to line-width ratio in Ps pose new challenging limitations on timing and the required laser power. Earlier theoretical work and first experiments already exhibit viable prospects for radiation pressure cooling to create unprecedented cold and dense Ps ensembles. Our extended numerical studies confirm very good prospects to simultaneously decelerate, cool and optically trap Ps atoms in a standard Doppler cooling geometry on the $1^3\mathrm{S}$--$2^3\mathrm{P}$ transition. Including the full Zeeman state manifolds and adding additional transverse lasers on the $2^3\mathrm{P}$--$3^3\mathrm{D}$ transition improves timing and final temperature to allow for optical trapping at the end. The required laser powers and geometry parameters to implement effective slowing and trapping within a time frame, where the majority of atoms is not annihilated, is in reach of current technology of $\mathrm{mJ}$ energy pulses of approximately $100\ \mathrm{ns}$ duration. Future extensions to collectively enhance cooling and trapping in optical cavities or hollow-core fibres should finally allow fast preparation of ultra-cold Ps systems as future basis of superradiant lasing and Bose--Einstein condensates.
Comments24 pages, 12 figures
