Photonic Quantum Networking of Trapped Ion Qubits

该项目将推动量子信息在本地和非本地联网方面的实验极限。人们普遍认为，未来的量子网络将需要稳定的量子存储器和能够穿越宏观距离的合适的量子通道。我们专注于利用囚禁离子的超精细基态作为量子存储器，并将单个光子用作量子通信通道。在我们团队以前在Yb+系统中工作的基础上，我们将研究(A)每个网络节点上更多的离子，(B)与附近光学元件进行预告门操作的增强概率，(C)通过利用Yb+系统中的红外跃迁来增加捕获离子节点之间的距离。这些方向代表着通往各种量子信息和量子通信协议的有希望的路线，包括分布式量子计算和长距离量子中继器电路。这项研究还可能带来一种有吸引力的方法来观察“无漏洞”的贝尔不等式性测试，其中纠缠离子相对于量子比特测量时间是空间状分离的。最后，这里讨论的离子/光子界面不一定是囚禁离子存储器所特有的，也可以应用于其他系统，如半导体或掺杂玻璃中的量子点。这项工作是实验室量子信息科学的核心，预计将吸引来自物理、计算机科学和工程等不同学科的各级和背景的学生的极大兴趣。这项研究的结果将在会议和研讨会上广泛传播，也将通过主要是本科生机构的讲座来传播。作为美国马里兰州吸引该地区最优秀的高中理科学生到大学公园的内部倡议的一部分，这项工作将在当地高中积极展示。在可能的情况下，向年轻学生和该领域的其他新手介绍这项研究将植根于对量子力学基础的特定方法，该方法更多地依赖于信息论的观点，如熵和测量，而较少依赖波力学、微分方程和复杂的数学。

This project will push experimental limits in the local and nonlocal networking of quantum information. It is generally accepted that future quantum networks will require both stable quantum memories and appropriate quantum channels that can traverse macroscopic distances. We concentrate on the use of hyperfine ground states of trapped ions as quantum memories, and individual photons as the quantum communication channel. Building on previous work from our group in the Yb+ system, we will investigate (a) larger numbers of ions at each network node, (b) enhanced probabilities of heralded gate operations with nearby optical elements, (c) larger distances between trapped ion nodes by exploiting infrared transitions in the Yb+ system. These directions represent promising routes toward a variety of quantum information and quantum communication protocols, including distributed quantum computing and long-distance quantum repeaters circuits. This research may also lead to an attractive method for observing a "loophole-free" Bell inequality test, where the entangled ions are space-like separated with respect to the qubit measurement time. Finally, the ion/photon interfaces discussed here are not necessarily specific to trapped ions memories, and may be applied to other systems such as quantum dots in a semiconductor or doped glass host.This work is at the heart of laboratory quantum information science, and it is expected to attract great interest from students at all levels and backgrounds from a variety of disciplines in physics, computer science, and engineering. The results of this research will be widely disseminated at meetings and workshops, and also through lectures at primarily undergraduate institutions. As part of an internal initiative at U. Maryland to attract the best high school science students in the area to College Park, this work will be aggressively presented at local high schools. Where possible, the presentation of this research to young students and other newcomers to the field will be rooted in a particular approach to the foundations of quantum mechanics that relies more on information theoretic viewpoints such as entropy and measurement and less on wave mechanics, differential equations, and complex mathematics.