Creating new states of matter with cavity QED: From photoassociation to spintronics

腔量子电动力学是物理学家探索非经典量子世界的主要工具之一。现代光学腔的高品质因子与腔模和单个量子发射体之间实现强耦合的能力相结合，使得腔QED成为探索幺正量子力学的完美实验室，着眼于直接测试量子力学的基本原理和开发量子信息处理设备。 传统的腔QED研究集中在实现强耦合机制，即量子力学与真空场的相互作用强于所有衰变过程。实验只是最近才证明连续的强耦合到一个单独的两级发射器的光学制度。在这里，我们提出了一个研究计划，研究腔QED的新应用的基础上新的扩展的Jaynes-Cummings模型。正如腔QED已经根据发射体和腔的类型沿着沿着两条轨道发展一样，法布里-珀罗腔中的原子或半导体微腔内生长的量子点，拟议的研究将着眼于这两个领域的新应用。具体而言，拟议的研究将开发新的理论模型来描述超冷原子气体通过腔场的拉曼光缔合。量子简并超冷气体的相干量子动力学沿着光学谐振腔的反馈导致了一种新的非线性量子系统，它混合了原子，分子和光波。驱动腔模式的反馈效应提供了对光缔合动力学的额外水平的控制，这将导致对以使用常规自由空间光缔合不可能的方式产生或解离的分子的数量的精确控制。 一个半经典分析这个系统的PI已经表明存在的分叉和分叉制度。PI计划开发和研究腔辅助光缔合（CAP）的全量子模型。特别令人感兴趣的是量子噪声对半经典分岔和量子态的影响。 第二个方向将是研究嵌入光学微腔中的单个量子点，该微腔具有连接到量子点的电引线，从而允许量子点的受控充电。电流流过腔耦合点的可能性开辟了新的方向，这是迄今尚未考虑的。PI最近表明，这样的系统可以成为纯自旋电流的有效来源。我们将探讨利用腔场来控制自旋电流及其统计的能力。

Cavity quantum electrodynamics (QED) is one of the main tools of physicists to explore the non-classical quantum world. The high quality factors of modern optical cavities combined with the ability to achieve strong coupling between a cavity mode and a single quantum emitter have made cavity QED the perfect laboratory for exploring unitary quantum mechanics with an eye towards directly testing fundamental principles of quantum mechanics and developing quantum information processing devices. Traditional studies of cavity QED have focused on achieving the strong coupling regime where the quantum mechanical interaction with the vacuum field is stronger than all decay processes. Experiments have only recently demonstrated continuous strong coupling to an individual two-level emitter in the optical regime. Here we propose a research program that studies new applications of cavity QED based on novel extensions of the Jaynes-Cummings model. Just as cavity QED has evolved along two tracks based on the type of emitter and cavity, atoms in a Fabry-Perot cavity or quantum dots grown inside of a semiconductor microcavity, the proposed research will look at new applications in both areas. Specifically, the proposed research will develop new theoretical models to describe Raman photoassociation of ultracold atomic gases via a cavity field. The coherent quantum dynamics of quantum degenerate ultracold gases along with the feedback of an optical resonator lead to a novel nonlinear quantum system that mixes atomic, molecular, and optical waves. The feedback effects of a driven cavity mode provides an extra level of control over the photoassociation dynamics that will lead to precise control over the number of molecules created or dissociated in a way that is impossible using conventional free space photoassociation. A semiclassical analysis of this system by the PI already indicates the presence of bifurcations and bistable regimes. The PI plans to develop and investigate a fully quantum model of cavity assisted photoassociation (CAP). Of particular interest will be the effect of quantum noise on the semiclassical bifurcations and bistable states. The second direction will be to study a single quantum dot embedded in an optical microcavity with electrical leads connected to the dot that allow controlled charging of the dot. The possibility of electrical current fowing through a cavity coupled dot opens up new directions, which have hitherto not been considered. The PI has recently shown that such a system can be an efficient source of pure spin current. The ability to use the cavity field to control the spin current and its statistics will be explored.