Quantum optics with thermal atomic vapours.

当代原子物理实验中的许多关键技术首先是在热原子蒸气中演示的。这些介质非常适合于量子光学实验，因为它们结合了强原子-光相互作用，具有较长的相干时间，以及众所周知的原子-原子相互作用。在新兴的量子信息和技术领域，使用原子蒸气有两个潜在的丰富领域：作为单光子的来源，以及作为窄带滤光器，以消除不需要的辐射源。本研究项目的主要目标是在量子光学实验的背景下，理解、描述和实验测量原子介质的过滤特性。之前在达勒姆所做的工作表明，增加一个大磁场可以极大地简化介质的理论模型。我们在这项研究中要解决的一个大问题是，在实现实验性超远距离滤光器时，能级结构的简化是否会导致更高的品质因数。以前的文献工作往往集中在对原子-光相互作用线形的定性理解上；相比之下，在这项工作中，我们方法学的新方面将是使用统计技术来比较我们理论和数值计算的定量一致性与包含热原子蒸气的介质的光学性质。学生将数值计算不同原子单元、场和温度下的斯托克斯参数(描述磁场中原子与光的相互作用)的期望值；然后进行定量的理论与实验比较；最后，在所获得的理解的基础上，确定并通过实验验证光学器件的最佳性能。

Many of the work-horse techniques of contemporary atomic physics experiments were first demonstrated in hot atomic vapours. These media are ideally suited for quantum-optics experiments as they combine strong atom-light interactions, with long coherence times, and well-understood and characterised atom-atom interaction.In the burgeoning field of quantum information and technology there are two potentially rich areas of using atomic vapours: as sources of single photons, and as narrowband filters to eliminate unwanted source of radiation.The key objectives of this research project are to understand, characterize numerically and measure experimentally the filtering properties of an atomic medium, in the context of quantum optics experiments. Previous work in Durham has shown that adding a large magnetic field dramatically simplifies the theoretical modelling of the medium. One of the big questions we shall address in this investigation is whether the simplification of the energy-level structure leads to higher figures of merit when realising experimental ultranarrow filters. Previous work in the literature has tended to concentrate on the qualitative understanding of the lineshape of the atom-light interaction; by contrast, in this work, the novel aspect of our methodology will be to use statistical techniques to compare the quantitative agreement of our theoretical and numerical calculations with the optical properties of the medium comprising a thermal atomic vapour. The student will calculate numerically the expected values of the Stokes parameters (that characterise atom-light interactions in the presence of a magnetic field) for different atomic cells, fields and temperatures; this shall be followed by quantitative theory-experiment comparisons; finally building on the understanding gained the optimal properties of optical devices shall be ascertained and verified experimentally.