The symmetric top molecule CaOCH3 is laser-cooled to submillikelvin temperatures. Laser cooling of symmetric top molecule Experimental progress over the past few decades has led to the mastery of ultracold atomic gases. A major thrust of current research is to extend this success to ultracold molecules, which would open qualitatively new perspectives for quantum information science, precision measurement, quantum chemistry, and other fields. The internal degrees of freedom in molecules preclude immediate implementation of conventional methods. Using a specific combination of rovibronic optical transitions, Mitra et al. report direct Sisyphus laser cooling of the symmetric top molecule CaOCH3 to temperatures below 1 millikelvin (see the Perspective by Hudson). The proposed scheme for cooling is potentially applicable to a wide range of nonlinear polyatomic molecules. Science, this issue p. 1366; see also p. 1304 Ultracold polyatomic molecules have potentially wide-ranging applications in quantum simulation and computation, particle physics, and quantum chemistry. For atoms and small molecules, direct laser cooling has proven to be a powerful tool for quantum science in the ultracold regime. However, the feasibility of laser-cooling larger, nonlinear polyatomic molecules has remained unknown because of their complex structure. We laser-cooled the symmetric top molecule calcium monomethoxide (CaOCH3), reducing the temperature of ~104 molecules from 22 ± 1 millikelvin to 1.8 ± 0.7 millikelvin in one dimension and state-selectively cooling two nuclear spin isomers. These results demonstrate that the use of proper ro-vibronic transitions enables laser cooling of nonlinear molecules, thereby opening a path to efficient cooling of chiral molecules and, eventually, optical tweezer arrays of complex polyatomic species.

中文翻译：

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对称顶部分子的直接激光冷却

对称的顶部分子 CaOCH3 被激光冷却到亚密尔文温度。对称顶分子的激光冷却 过去几十年的实验进展导致对超冷原子气体的掌握。当前研究的一个主要推动力是将这一成功扩展到超冷分子，这将为量子信息科学、精密测量、量子化学和其他领域开辟全新的视角。分子的内部自由度妨碍了传统方法的立即实施。Mitra 等人使用 rovibronic 光学跃迁的特定组合。报道了对称顶部分子 CaOCH3 的 Sisyphus 激光直接冷却到 1 毫开尔文以下的温度（参见 Hudson 的观点）。所提出的冷却方案可能适用于广泛的非线性多原子分子。科学，这个问题 p。第1366章 另见第 1304 超冷多原子分子在量子模拟和计算、粒子物理学和量子化学中具有潜在的广泛应用。对于原子和小分子，直接激光冷却已被证明是超冷状态下量子科学的强大工具。然而，由于其复杂的结构，激光冷却更大的非线性多原子分子的可行性仍然未知。我们激光冷却对称顶分子一甲醇钙 (CaOCH3)，在一维上将~104 个分子的温度从 22 ± 1 毫开尔文降低到 1.8 ± 0.7 毫开尔文，并对两种核自旋异构体进行状态选择性冷却。