近日，美国普林斯顿大学的Lawrence W.Cheuk及其研究小组取得一项新进展。经过不懈努力，他们揭示光镊阵列中分子的拉曼边带冷却过程。相关研究成果已于2024年1月22日在国际知名学术期刊《自然—物理学》上发表。

该研究团队展示了被捕获在光镊阵列中的CaF分子的拉曼边带冷却技术。与高磁场依赖的方案不同，该研究的方案保持了分子内部状态的纯度。研究人员测量了高基态分数，并获得了每个粒子的低运动熵。这种低温状态可以实现更长的相干时间和更高保真度的分子量子比特门，这对于量子信息处理和量子模拟至关重要。随着技术的进一步改进，拉曼边带冷却有望为大分子样品的量子简并提供一条途径，并可以扩展到多原子分子组分。

据悉，超冷分子因其丰富的内部结构和相互作用，已被视为量子科学和精密测量的候选平台。直接激光冷却被寄予厚望，有望成为一种快速有效的方法，使分子达到超冷温度。然而，对于被捕获的分子，激光冷却到量子运动基态仍是一个巨大的挑战。一种有望实现这一目标的技术是拉曼边带冷却，这种技术在被捕获的离子和原子中已经得到了验证。

附：英文原文

Title: Raman sideband cooling of molecules in an optical tweezer array

Author: Lu, Yukai, Li, Samuel J., Holland, Connor M., Cheuk, Lawrence W.

Issue&Volume: 2024-01-22

Abstract: Ultracold molecules have been proposed as a candidate platform for quantum science and precision measurement because of their rich internal structures and interactions. Direct laser-cooling promises to be a rapid and efficient way to bring molecules to ultracold temperatures. However, for trapped molecules, laser-cooling to the quantum motional ground state remains an outstanding challenge. A technique capable of reaching the motional ground state is Raman sideband cooling, first demonstrated in trapped ions and atoms. Here we demonstrate Raman sideband cooling of CaF molecules trapped in an optical tweezer array. Our protocol does not rely on high magnetic fields and preserves the purity of molecular internal states. We measure a high ground-state fraction and achieve low motional entropy per particle. The low temperatures we obtain could enable longer coherence times and higher-fidelity molecular qubit gates, desirable for quantum information processing and quantum simulation. With further improvements, Raman sideband cooling will also provide a route to quantum degeneracy of large molecular samples, which could be extendable to polyatomic molecular species.

DOI: 10.1038/s41567-023-02346-3

Source: https://www.nature.com/articles/s41567-023-02346-3