A quantum gate between a flying optical photon and a single trapped atom
A quantum gate between a flying optical photon and a single trapped atom
复制标题
DOI：
10.1038/nature13177
复制
发表时间：
2014-04-10
期刊：
影响因子：
64.8
通讯作者：
Ritter, Stephan
中科院分区：
文献类型：
--
作者：
Reiserer, Andreas;Kalb, Norbert;Ritter, Stephan
对单个量子系统的控制稳步增加，支持了一种量子技术的推广，这种技术可以提供超过任何经典设备的功能。在过去的十年里，人们探索了两个特别有前景的应用：基于光子的量子通信，它保证了不可破解的加密(1)，但仍然必须在长距离上扩展到高速率；以及量子计算，如果它可以扩展到大量的量子比特(Qbit)，它将从根本上提高可计算性(2)。人们很早就意识到，光量子比特和物质量子比特的混合系统(3)可以解决每个场的可伸缩性问题-使用量子中继器4进行通信，以及使用较小的量子处理器(5，6)之间的光学互连进行计算。为此，开发一种健壮的两量子比特门，允许连接遥远的计算节点是一项“紧迫的挑战”(6)。在这里，我们展示了在单个囚禁原子的自旋态和微弱激光脉冲中包含的光学光子的偏振态之间的量子门。所提出的门机制(7，8)是确定性的和健壮的，并且有望适用于几乎任何物质量子比特。它是基于光子量子比特从提供强烈光-物质耦合的腔中反射而来的。为了展示它的多功能性，我们使用量子门从可分离的输入态创建原子-光子、原子-光子-光子和光子-光子纠缠态。我们希望我们的实验能够实现各种应用，包括原子(9)和光子(10)团簇态和薛定谔-猫态(11)的产生，确定性光子Bell态测量(12)，可伸缩量子计算(7)和使用冗余量子奇偶码的量子通信(13)。
The steady increase in control over individual quantum systems supports the promotion of a quantum technology that could provide functionalities beyond those of any classical device. Two particularly promising applications have been explored during the past decade: photon-based quantum communication, which guarantees unbreakable encryption(1) but which still has to be scaled to high rates over large distances, and quantum computation, which will fundamentally enhance computability(2) if it can be scaled to a large number of quantum bits (qubits). It was realized early on that a hybrid system of light qubits and matter qubits(3) could solve the scalability problem of each field-that of communication by use of quantum repeaters4, and that of computation by use of an optical interconnect between smaller quantum processors(5,6). To this end, the development of a robust two-qubit gate that allows the linking of distant computational nodes is "a pressing challenge"(6). Here we demonstrate such a quantum gate between the spin state of a single trapped atom and the polarization state of an optical photon contained in a faint laser pulse. The gate mechanism presented(7,8) is deterministic and robust, and is expected to be applicable to almost any matter qubit. It is based on reflection of the photonic qubit from a cavity that provides strong light-matter coupling. To demonstrate its versatility, we use the quantum gate to create atom-photon, atom-photon-photon and photon-photon entangled states from separable input states. We expect our experiment to enable various applications, including the generation of atomic(9) and photonic(10) cluster states and Schrodinger-cat states(11), deterministic photonic Bell-state measurements(12), scalable quantum computation(7) and quantum communication using a redundant quantum parity code(13).