Remote Entanglement of Trapped Ions and Loophole-Free Bell Inequality Tests

本研究项目旨在对单原子离子-单光子系统中的量子纠缠进行实验研究。纠缠是量子力学最显著的特征之一，它导致物理系统的各个组成部分之间存在很强的相关性，而不管它们之间的距离有多远。这些关联被爱因斯坦称为“远距离的诡异行为”。这个项目中的纠缠是由囚禁的原子离子控制的光子自发发射产生的；对两个不同原子发射的光子的关联测量导致了这些原子的纠缠。由于光子可以在光纤中远距离传输，两个纠缠的原子可以被极大地分开。物理学家约翰·贝尔于1964年设计了是否需要量子力学来解释这些关联的测试。该项目的最终目标是在贝尔不等性测试中测量相距约1公里的离子之间的相关性，并提供一种测试“远距离诡异行为”是否真的发生的手段，填补先前实验中的一个“漏洞”。我们将详细研究纠缠和退相干，并进行完全无漏洞的贝尔不等式性检验。这项研究将加深我们对量子力学的理解，并为量子信息科学开发新的有用工具和概念。原子-光子纠缠态的可能应用有很多种。它们的范围从用于安全长距离量子通信的实用量子中继器系统到有点未来主义的簇态量子计算机。该计划的教育部分包括为本科生和研究生提供研究培训，积极让物理学中代表性不足的群体的学生参与尖端研究，开发和建立量子信息科学的本科生和研究生课程，以及通过公开讲座接触更广泛的社会。与华盛顿大学计算机科学和工程系合作，将通过在华盛顿大学实验室开展积极的研究项目，对信息技术行业专业人员进行动手培训。

This research program aims at the experimental study of quantum entanglement in system of single trapped atomic ions and single photons. Entanglement, one of the most striking features of quantum mechanics, leads to strong correlations between the various components of a physical system, regardless of the distance separating them. These correlations were called by Einstein "spooky action at a distance." The entanglement in this project is produced by controlled spontaneous emission of photons by trapped atomic ions; correlated measurement of the photons emitted by two distinct atoms leads to entanglement of these atoms. Since photons can be transmitted over a long distance in optical fibers, the two entangled atoms can be vastly separated. Tests of whether quantum mechanics is required to explain these correlations were designed by physicist John Bell in 1964. The eventual goal of this project is measure the correlations between ions that are approximately 1 km apart in a test of the Bell inequality and providing a means of testing whether "spooky action at a distance" actually occurs, closing a "loophole" in prior experiments. Entanglement and decoherence will be studied in great detail, and a completely loophole-free Bell inequality test will be performed. The research will further our understanding of quantum mechanics, and develop new, useful tools and concepts for quantum information science. Possible applications of the atom-photon entangled state are numerous. They range from a practical quantum repeater system for secure long-distance quantum communications to a somewhat futuristic cluster-state quantum computer. The educational part of this program includes research training for undergraduate and graduate students and actively involving students from groups underrepresented in physics in cutting edge research, developing and establishing undergraduate and graduate curriculum in quantum information science, and reaching out to the broader society through public lectures. In collaboration with the University of Washington Computer Science and Engineering Department, the hands-on training of information technology industry professionals will be done through their work on the active research projects in the University laboratory.