EIT-based quantum light-matter interfaces using ultracold atoms

我们正试图建立一个系统，在量子水平上连接光和原子。量子信息处理承诺超越当前技术（绝对牢不可破的密码系统，某些算法的指数级更快的计算，等等），但需要发明新技术来实现。量子光（单光子）已经用于安全通信的商业原型中，但将这种系统转变为计算设备将需要某种“光子开关”，因为留给它们自己的设备，一束光将平静地穿过另一束光，而没有任何可用于计算的相互作用。这类技术最有前途的途径之一涉及到原子的使用，原子与光有强烈的相互作用。问题是，到目前为止，观察到的相互作用已经弱了数十亿倍，无法让单个量子光粒子（光子）相互切换。最近的建议表明，有可能缩小这一差距，但这需要特别设计的光源和仔细控制的激光冷却原子。幸运的是，在我们的实验室里，我们已经有了铷原子的“玻色-爱因斯坦凝聚体”（冷却到远低于绝对零度的百万分之一度），以及我们专门为与铷相互作用而开发的新型量子纠缠光源。这一提议将使我们能够获得两种重要的设备，用于以量子逻辑中所需的谨慎方式捕获和操纵原子，以及产生和剪裁预期增强所需相互作用的特定光束。这是一个国际上竞争激烈的研究领域，但我们处于一个很好的起点，如果我们成功了，这种独特的能力将为原子、分子和光学物理学，特别是量子信息处理打开新的大门。

We are trying to build a system to interface light and atoms at the quantum level. Quantum information processing promises capabilities beyond anything possible with current technology (absolutely unbreakable cryptographic systems, exponentially faster computation of certain algorithms, et cetera), but will require the invention of new techniques to realize. Already, quantum light (single photons) is used in commercial prototypes for secure communication, but turning such systems into computational devices will require some sort of "photon switch," since left to their own devices, one beam of light will placidly pass through another without any kind of interaction which could be used to compute. One of the most promising avenues for such technologies involves the use of atoms, which interact strongly with light. The problem is that so far, the interactions observed have been billions of times too weak to let individual quantum particles of light (photons) switch one another. Recent proposals suggest that it may be possible to close this gap, but this involves specially designed sources of light and carefully controlled laser-cooled atoms. We are fortunate in our lab to already have a "Bose-Einstein condensate" of Rubidium atoms (cooled to well below a millionth of a degree above absolute zero), and a novel source of quantum-entangled light we have developed specifically for interactions with Rubidium. This proposal will allow us to acquire two essential pieces of equipment for trapping and manipulating the atoms in the careful manner required for use in quantum logic, and for generating and tailoring the specific beams of light which are predicted to enhance the desired interaction. This is a highly competitive area of research internationally, but we are in an excellent starting position, and if we succeed, this unique capability will open new doors in atomic, molecular, and optical physics, and particularly for quantum information processing.