New applications of dark states in metrology and quantum control -- Visiting Researcher

当原子系统在相干叠加状态下制备时，可以观察到极窄的相干居群捕获（CPT）和相关的电磁感应透明（EIT）共振，其中原子相干抵消或减少了吸收。相关的早期研究包括在比萨进行的测量，其中引入了暗共振和原子种群捕获等术语。最近对该主题的兴趣不断扩大，不仅是因为涉及量子相干性的迷人物理学，而且还因为在新技术和设备的开发以及基础研究的新方法方面有许多潜在的应用，例如飞行减速，非线性光学，量子信息存储，频率标准和精密磁强计。在频率标准的背景下，应该注意的是，基于CPT的原子钟已经被NIST小组详细研究过，第一个商业上可用的相干居群捕获原子频率标准现在由Kernco公司（www.kernco.com）生产。这里描述的研究旨在实验研究暗态在计量和量子控制领域的新应用。这将通过在偶极子阱中使用冷原子来实现。这为热原子蒸汽提供了显著的优势，通常用于EIT/CPT研究，这对于这里设想的研究是必不可少的。计划对一个大的原子云和一个被捕获的原子进行测量。提议者已经为提议的研究做了大量的背景工作。还开始与Brana Jelenkovic教授（塞尔维亚贝尔格莱德）合作，以获得探测和控制单个原子的具体技术方面的必要专门知识。现在申请资金，允许耶伦科维奇教授访问伦敦大学学院两个月，在此期间将完成实验的一些关键方面。

When an atomic system is prepared in a coherent superposition state, extremely narrow Coherent Population Trapping (CPT) and related Electromagnetically Induced Transparency (EIT) resonances can be observed where the atomic coherence cancels, or reduces, absorption.The relevant early studies include measurements performed in Pisa where terms such as dark resonance and atomic population trapping were introduced. The recently expanding interest in the topic is due not only to the fascinating physics involving quantum coherence but also to the fact that there are many potential applications with relevance both in development of new techniques and devices, and in new approaches to fundamental studies, such as slowing oflight, nonlinear optics, quantum information storage, frequency standards, and precisemagnetometers. In the context of frequency standards, it should be noticed that CPT based atomic clocks have been studied in detail by the NIST group, and the first commerciallyavailable Coherent Population Trapping atomic frequency standard is now produced by Kernco, Inc (www.kernco.com).The research described here aims to investigate experimentally new applications of dark states in the domain of metrology and quantum control. This will be done by using cold atoms confined in a dipole trap. This offers significant advantages with respect to a thermal atomic vapour, as commonly used in EIT/CPT studies, and it is essential for the investigation envisaged here. Both measurement on a large cloud of atoms, and on a single trapped atom are planned.The proposer has already made a significant amount of background work needed for the proposed research. A collaboration was also started with Prof. Brana Jelenkovic (Belgrade, Serbia) to acquire the necessary expertise in the techniques specific to the detection and control ofa single atom. Funds are now requested to allow Prof. Jelenkovic to visit UCL for two months during which some key aspects of the experiment will be finalised.