Hepworth Tom R, Ruttley Daniel K, von Gierke Fritz, Gregory Philip D, Guttridge Alexander, Cornish Simon L
Department of Physics, Durham University, Durham, UK.
Joint Quantum Centre Durham-Newcastle, Durham University, Durham, UK.
Nat Commun. 2025 Aug 4;16(1):7131. doi: 10.1038/s41467-025-62275-y.
Rotational states of ultracold polar molecules possess long lifetimes, microwave-domain coupling, and tunable dipolar interactions. The availability of numerous rotational states has inspired many applications, including simulating quantum magnetism, encoding high-dimensional qudits and generating large synthetic dimensions. However, engineering the coherent superpositions of multiple rotational states needed for these applications is difficult owing to strong differential light shifts. Here, we overcome this challenge using individual molecules confined in near-magic wavelength optical tweezers. Through precision Ramsey spectroscopy, we find the exact magic wavelengths and sensitivities to detuning errors for multiple rotational state superpositions. We find for traps polarised parallel to the quantisation axis, the magic wavelengths are closely clustered enabling long-lived coherence across multiple rotational states simultaneously. Using a generalised Ramsey sequence, we demonstrate second-scale coherent spin-1 dynamics encoded in three rotational states and perform multiparameter estimation. With modest experimental improvements, we predict second-scale coherence across ten rotational states is achievable.
超冷极性分子的转动态具有长寿命、微波域耦合和可调谐偶极相互作用。众多转动态的存在激发了许多应用，包括模拟量子磁性、编码高维量子比特以及生成大的合成维度。然而，由于强烈的微分光频移，工程实现这些应用所需的多个转动态的相干叠加是困难的。在这里，我们利用限制在近魔幻波长光镊中的单个分子克服了这一挑战。通过精确的拉姆齐光谱，我们找到了多个转动态叠加的精确魔幻波长以及对失谐误差的灵敏度。我们发现，对于平行于量子化轴极化的阱，魔幻波长紧密聚集，能够同时实现多个转动态的长寿命相干。使用广义拉姆齐序列，我们展示了编码在三个转动态中的秒级相干自旋-1动力学，并进行了多参数估计。通过适度的实验改进，我们预测可以实现跨越十个转动态的秒级相干。
