分子有效减速、强度梯度冷却与高效囚禁及其光学势蒸发冷却：一条新的技术路线

由于分子内部复杂的能级结构，并存在着许多暗态，因而难以实现分子束的高效激光减速和磁光囚禁（多普勒冷却），以至于目前3D-MOT中的冷分子数目仅为10^4-10^5，密度仅为10^5/cm^3。为此，本项目将提出一种实现分子有效减速、高效装载和强度梯度冷却的新方法。该方法首先采用新颖高效Stark减速器或驻波场受激辐射力实现超声分子束的有效减速；然后，将冷分子通过静电阱和四极磁阱高效装载到空心光阱，并在空心光阱中实现MgF分子的强度梯度（Sisyphus）冷却和绝热冷却，以获得数目为10^6-10^7、温度为8-60μK、密度为10^10-10^11/cm^3的超冷分子，为下一步光学势蒸发冷却和全光型分子BEC的实现奠定基础，可望在国际上首次解决分子激光冷却中冷分子数目少、密度极低的难题，取得若干重要的创新性甚至原创性成果，部分成果达到国际领先水平，甚至实现国际引领。

Usually, it is difficult to realize an efficient laser slowing of molecular beam and high-effective magneto-optical trap (Doppler cooling), so that the number of cold molecules in 3D-MOT is only about 10^4-10^5, and its density is only 10^5/cm^3. For this, we propose a new method to realize effectively slowing, high-efficiently loading and sub-Doppler laser cooling for molecules. In our proposed scheme, we first use a novel high-efficient electrostatic Stark decelerator or simulated force in a standing-wave light to realize effectively slowing of a supersonic molecular beam; Afterwards, the slowed cold molecular beam is first loaded into an electrostatic trap, and then loaded into a magnetic trap, and finally loaded into a blue-detuned hollow optical trap. In final, we use intensity gradient of hollow optical trap itself to realize Sisyphus cooling (a new sub-Doppler cooling mechanism) of MgF molecules in hollow optical trap, and obtain an ultracold molecular sample with a number of 10^6-10^7, a temperature of 8-60µK, and a density of 10^10-10^11/cm^3), and then lay the experimental ground-work for next optical-potential evaporative cooling of molecules and the realization of all-optical molecular BEC. We hope first solve a difficult question about fewer molecular number and extremely low molecular density in laser cooling of molecules in the world, and obtain some important new even original results, and some results will arrive at international advanced level.