Efficient creation of translational cold heteronuclear dimers in the rovibrational ground state from ultracold atoms via photoassociation followed by optical pumping

超冷异核红细胞二聚体是通过光缔合产生的。这些分子处于高度激发的振动状态。这个项目涉及到激发的分子转移到电子基态的最低振动能级，即绝对基态。只有深束缚的异核二聚体才具有显著的偶极矩，这使得在强相互作用区域进行实验成为可能。通过这种相互作用，这种分子可能会成为未来量子计算机的Q比特。本项目研究了在绝对基态下提高转移效率和由此产生更多基态分子的两种可能性：第一种技术，应用受激拉曼绝热通道(STIRAP)，如果以良好控制的顺序施加两个激光场，则允许在两个态之间完全转移。第二种技术是选择合适的能级来提高效率，这对于通过混合能级在单重态和三重态流形之间的转移特别有意义。转移过程的另一个方面是分子的超精细状态，这对可能的量子计算机特别重要。对于绝对基态，不同的超精细态是简并的，但纯超精细态的制备对于量子计算是必不可少的，并且可以在转移方案中解决。

Ultracold heteronuclear RbCs dimers are produced via photoassociation. These molecules are in highly excited vibrational states. This project is concerned with the transfer of the excited molecules to the lowest rovibrational level of the electronic ground state, i.e., the absolute ground state. Only deeply bound heteronuclear dimers carry a significant dipole moment, which makes experiments in the strongly interacting regime possible. Via this interaction, such molecules may serve as q-bits for future quantum computers. This project investigates two possibilities for improving the efficiency of the transfer and the resultant larger number of ground state molecules in the absolute ground state: The first technique, applying Stimulated Raman Adiabatic Passage (STIRAP) allows for a complete transfer between two states if two laser fields are applied in a well controlled sequence. The second technique is selecting appropriate levels to increase the efficiency, which is of particular interest for a transfer between singlet and triplet manifold via a mixed level. Another aspect of the transfer process is the hyperfine state of the molecule, which is of particular importance for possible quantum computers. The different hyperfine states are degenerate for the absolute ground state, but the preparation of a pure hyperfine state is essential for quantum computing and can be addressed in the transfer scheme.