超冷极性费米分子23Na40K的最低振转能级制备和量子态操控

处于纳开尔文温度的超冷分子是目前量子物理领域的重要研究方向之一, 因为分子具有比原子更加丰富的能级结构，为人们提供了更多的量子控制手段。本项目将制备和研究纳开尔文量级的基态极性偶极费米分子，也就是处于最低振转能级的分子23Na40K，这是目前为数不多的化学稳定的基态分子，寿命可以得到秒量级。实验上首先通过冷却技术获得处于纳开尔文温度的大数目的异核原子样品，再结合Feshbach共振技术将原子制备为弱束缚分子，最后通过STIRAP技术将分子转移到最低振转能态上。采用射频和微波脉冲实现基态分子的量子态操控，通过研究处于不同量子态分子的碰撞特性，寻找可以处于长相干时间的分子态组合。本项目的顺利开展将增强我们对超冷基态分子的量子操控能力，为以后在超冷分子系统中开展基于长程偶极-偶极相互作用的量子模拟、量子信息的应用提供基础。

Ultracold molecules at temperatures of nK is an important direction in quantum physics, because the much richer energy structure in molecules compared with atoms, which provide more tools for quantum manipulation. In this project, the ultracold dipolar gas of fermionic molecules 23Na40K in absolute ground state (the rovibrational ground state) are prepared and controlled. The molecules 23Na40K with lifetime on the order of second are one of chemically stable molecules in ground state. The mixture of large 23Na and 40K atoms are trapped and cooled by gray molasses and evaporation, and then used to create weakly bound molecules near the Feshbach resonance. The dipolar molecules in lowest rovibrational ground state are transferred from weakly bound molecules using stimulated rapid adiabatic passage(STIRAP) via a excited molecular state. The quantum state of molecules are prepared by radio frequency and microwave pulse to study the collision properties for searching the mixture with longer coherence time. The works in this project help us to enhance the ability on manipulating ultracold molecules in ground state, and provide many experience and experimental technique for quantum simulation, quantum information based on the long range dipole-dipole interaction in ultracold molecules.