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。 量子信息处理承诺的能力超出了现有技术的任何可能性（绝对不可破解的密码系统，某些算法的指数速度计算等），但需要发明新技术来实现。 量子光（单光子）已经用于商业原型的安全通信，但将这样的系统变成计算设备将需要某种“光子开关”，因为留给自己的设备，一束光将平静地通过另一束光，而没有任何可用于计算的相互作用。 这种技术最有希望的途径之一是使用与光强烈相互作用的原子。 问题是，到目前为止，观察到的相互作用已经弱了数十亿倍，无法让单个光量子粒子（光子）相互转换。 最近的提议表明，有可能缩小这一差距，但这需要特别设计的光源和精心控制的激光冷却原子。 我们很幸运，在我们的实验室已经有了铷原子的“玻色-爱因斯坦凝聚体”（冷却到绝对零度以上的百万分之一度以下），以及我们专门为与铷的相互作用开发的量子纠缠光源。 这一提议将使我们能够获得两种基本设备，一种是以量子逻辑所需的谨慎方式捕获和操纵原子，另一种是产生和剪裁特定的光束，这些光束预计将增强所需的相互作用。 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，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.