Atom-Photon Entanglement and Functional Quantum Network Nodes with Atomic Ensembles

世界各地都在积极地发展量子力学方法来处理、存储和传输信息。量子处理器不同于现有的经典系统，因为它们利用量子物理的独特特征来实现超越经典的功能。其中包括有效解决当前棘手的计算问题的潜力，模拟复杂的物理系统以开发新材料，以及在远程位置之间安全传输信息的能力。目前正在积极研究的方法之一是使用存储在中性原子中的量子比特（量子位）进行记忆和处理，并使用光子（光粒子）进行长距离信息传输。一个必要的步骤是纠缠，即单个光粒子，光子和/或原子可以与另一个光子或另一个原子相关联，这样即使它们不在同一位置，测量一个的性质也会立即影响另一个的性质。虽然原子和光子之间的纠缠已经在许多实验中得到证明，但尚未实现的是将原子-光子纠缠与可以处理和存储信息的原子量子位结合起来的能力。本研究的主要目标是在单一系统中展示原子-光子纠缠和基于原子的量子逻辑门，这可以形成未来量子网络的基础。该研究项目还将有助于培养学生从事科学和工程方面的职业。来自不同背景的人们将接受现代实验科学的教育和培训，并将具备在物理学和信息科学之间架起桥梁的能力。培训将通过课程丰富和直接参与大学的研究项目来进行。我们还将向当地的麦迪逊社区介绍物理学对信息技术的重要性，以及量子信息科学领域的新发展。物理系的公众参观日、实验室之旅、教师对当地学校的访问以及对高中生的指导将促进对公众的宣传。我们的技术方法是基于使用含有10-100个铷原子的小原子云，用于在原子和光子之间产生纠缠的双重目的，并作为小型量子处理器中的量子位。我们将使用由原子的高激发里德伯态介导的远程相互作用，在多原子系综中编码的量子位之间以及系综与光之间创建确定性纠缠。这些能力将构成长距离纠缠分配和量子网络所需的高效量子中继器架构的基础。

The development of quantum mechanical approaches to processing, storage, and transmission of information is being actively pursued around the world. Quantum processors are distinct from existing classical systems in that they harness unique features of quantum physics to enable beyond classical capabilities. These include the potential for efficiently solving currently intractable computational problems, for simulating complex physical systems in order to develop new materials, and the ability to transmit information securely between distant locations. One of the approaches being actively pursued is to use quantum bits (qubits) stored in neutral atoms for memory and processing and to use optical photons (particles of light) for long distance transmission of information. A necessary step is entanglement, that is where a single particle of light, a photon, and/or an atom can be correlated with another photon or another atom such that measuring the properties of one instantaneously affects the properties of the other even if they are not in the same location. While entanglement between atoms and photons has been demonstrated in many experiments what has not yet been achieved is the ability to combine atom-photon entanglement with atomic qubits that can process and store information. The major goal of this research is to demonstrate atom-photon entanglement and atom based quantum logic gates in a single system that can form the basis for future quantum networks. The research program will also contribute to the training of students for careers in science and engineering. People from diverse backgrounds will be educated and trained in modern experimental science, and will be equipped to bridge the boundary between physics and information science. Training will occur via curriculum enrichments, and through direct participation in the University based research program. We will also inform the local Madison community about the importance of physics to information technology, and the new developments in the area of quantum information science. Outreach to the public will be facilitated by public visiting days at the Physics department, laboratory tours, faculty visits to local schools, and mentoring of high school students.Our technical approach is based on the use of small clouds of atoms with from 10-100 Rubidium atoms for the dual purpose of creating entanglement between atoms and photons, and as qubits in a small quantum processor. We will use long range interactions mediated by highly excited Rydberg states of atoms to create deterministic entanglement between qubits encoded in multi-atom ensembles and between ensembles and light. These capabilities will form the basis for efficient quantum repeater architectures needed for long distance distribution of entanglement and quantum networking.