Coherent Control and Precision Spectroscopy of a Polyatomic Molecular Ion

多原子分子离子的相干控制和精密光谱

• 批准号: 1806209
• 负责人: David Leibrandt
• 金额: $ 26.55万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-09-01 至 2022-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1806209&HistoricalAwards=false
• 关键词: Coherent; Control; Precision; Spectroscopy; Polyatomic

This project is motivated by the opportunity to achieve coherent control of the quantum state of a single polyatomic molecule, and to exploit this control for precision measurements. This project will focus on trapping and controlling the molecular ion N_2H+, but the approach can be generalized to many other molecular ions. The N_2H+ molecular ion will be co-trapped and sympathetically cooled with a calcium ion to near the ground state of their shared motion. Pure quantum states of the molecular ion can then be initialized by projective measurements using quantum-logic spectroscopy, as recently demonstrated on the calcium hydride ion CaH+ by the investigators. This is important because this approach can advance quantum chemistry and may impact materials science and the chemical, biological, and pharmaceutical industries. In addition, new and superior reference spectra for astronomical observations could lead to a better understanding of interstellar gas clouds and the universe, including stringent tests of physics beyond the standard model. Ultimately, controlling molecules at the quantum level may enable precisely orchestrated collisions and fully controlled quantum chemistry.While laser cooling, trapping, and precision measurements of diatomic molecules are making tremendous progress, polyatomic molecules have eluded precision studies due to their complicated level structures and vast number of populated states. This project will extend the technique of quantum-logic spectroscopy to prepare pure quantum states of polyatomic molecules, and to manipulate and detect their states with minimal perturbations such as Doppler or pressure shifts. Precision spectroscopy will ultimately only be limited by the lifetime of the states and can therefore be pushed to levels that have only been reached previously in optical atomic clocks. The molecule N_2H+ was one of the first ions observed in interstellar clouds and remains one of the most important tracers in astrophysics. Improved spectroscopic precision might enable improved constraints on possible spatial or temporal variations of fundamental constants. This work will also train a student at the University of Colorado in techniques needed for quantum logic spectroscopy.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

该项目的动机是有机会实现对单个多原子分子量子态的相干控制，并利用这种控制进行精确测量。本项目的研究重点是对分子离子N_2H+的捕获和控制，但该方法可以推广到许多其他分子离子。N_2H ~+分子离子将与钙离子共俘获并被冷却到基态附近。分子离子的纯量子态可以通过使用量子逻辑光谱学的投影测量来初始化，正如最近研究人员在氢化钙离子CaH+上所证明的那样。 这很重要，因为这种方法可以推进量子化学，并可能影响材料科学以及化学，生物和制药行业。此外，新的和上级的天文观测参考光谱可以导致更好地了解星际气体云和宇宙，包括超越标准模型的严格的物理测试。最终，在量子水平上控制分子可能实现精确协调的碰撞和完全受控的量子化学。虽然双原子分子的激光冷却，捕获和精确测量正在取得巨大进展，但多原子分子由于其复杂的能级结构和大量的填充态而无法进行精确研究。该项目将扩展量子逻辑光谱技术，以制备多原子分子的纯量子态，并以最小的扰动（如多普勒或压力位移）操纵和检测它们的状态。精确的光谱学最终只会受到状态寿命的限制，因此可以被推到以前只有光学原子钟才能达到的水平。N_2H+是最早在星际云中观测到的离子之一，至今仍是天体物理学中最重要的示踪剂之一。光谱精度的提高可能会改善对基本常数可能的空间或时间变化的约束。 这项工作还将在科罗拉多大学培训一名学生掌握量子逻辑光谱学所需的技术。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。