Development and magnetometric application of powerful ultraviolet frequency comb lasers

原子磁力计用于许多应用，从化学分析、基础物理测试和空间探索到医学诊断、导航陀螺仪和矿物地球物理勘探。磁力计在给定测量时间内可以检测到的最弱磁场定义了其灵敏度，并且应用受益于更高的灵敏度。 原子磁力计中的原子本质上就像指南针。最初将它们都对准同一方向会使磁力计更加灵敏。然而，经过一段时间，称为弛豫时间，他们总是成为失调，由于环境的影响。此外，罗盘指针方向的读出方式也会影响灵敏度，因为它容易受到外部干扰。最先进的原子磁力计受到权衡的困扰：最长的弛豫时间是用惰性气体中的核自旋获得的，而最好的读出方法是直接光学检测。到目前为止，光学探测还不能直接应用于惰性气体中的核自旋，因为没有合适的紫外激光器。弛豫时间和读出方法之间的折衷限制了灵敏度。类似地，用于惰性气体原子的初始对准的现有方法（称为超极化方法）由于缺乏直接光学访问而带来限制。 该研究计划的重点是开发新型紫外激光器及其在惰性气体核自旋磁力计直接光学探测新领域中探索物理现象的用途。长弛豫时间和直接光学检测的组合将导致破纪录的磁力灵敏度。该计划的长期目标是推动基础物理学的磁力测试的界限（包括广义相对论的测试和暗物质的搜索），并使用低场核磁共振光谱法来揭示被高磁场掩盖的现象。这种光谱仪也将成为一种可访问的桌面替代品，以取代目前用于化学和生物化学分析的大型、昂贵、访问受限的低温冷却超导体机器。在短期内，该计划将实现三个目标。目标I将开发一种强大的红外激光器，目标II将使用该激光器产生适合在惰性气体核自旋磁力测量中直接光学检测的紫外激光器。第三项目标将利用紫外激光器研究惰性气体129氘直接超极化和磁力测量的新机制的物理学。

Atomic magnetometers are used in a many applications, ranging from chemical analysis, tests of fundamental physics and space exploration, to medical diagnostics, navigation gyroscopes and geophysical exploration for minerals. The weakest magnetic field a magnetometer can detect in a given measurement time defines its sensitivity, and applications benefit from higher sensitivity. Atoms in atomic magnetometers are essentially like compass needles. Initially aligning them all in the same direction makes the magnetometer more sensitive. However, after some time, called relaxation time, they always become misaligned due to environmental influences. Additionally, the manner in which the direction of the compass needles is read out also influences sensitivity, as it can be susceptible to external interference. State of the art atomic magnetometers are plagued by a trade-off: the longest relaxation times are obtained with nuclear spin in noble gases, while the best readout method is direct optical detection. So far, optical detection could not be directly applied to nuclear spin in noble gases, since a suitable ultraviolet laser was not available. The trade-off between relaxation time and readout method limits sensitivity. Similarly, existing methods for the initial alignment of the noble gas atoms, called hyperpolarization methods, bring about limitations due to the lack of direct optical access. This research program is focused on the development of novel ultraviolet lasers and their use in exploring physical phenomena in a new domain of direct optical detection in noble gas nuclear spin magnetometers. The combination of long relaxation times and direct optical detection will result in record breaking magnetometric sensitivity. The long term goals of this program are to push the boundaries of magnetometric tests of fundamental physics (including tests of general relativity and searches for dark matter) and to use low-field nuclear magnetic resonance spectrometry to uncover phenomena masked by high magnetic fields. This spectrometer would also make an accessible tabletop alternative to the large, expensive, access-restricted cryogenically-cooled-superconductor based machines currently employed for chemical and biochemical analysis. In the short term, this program will pursue three objectives. Objective I will develop a powerful infrared laser, which Objective II will use to generate ultraviolet lasers suitable for direct optical detection in magnetometry with noble gas nuclear spin. Objective III will apply an ultraviolet laser to study the physics of a new regime of direct hyperpolarization and magnetometry with the noble gas 129Xe.