Hybrid quantum dot-nanowire heterostructures for deterministic biphoton quantum communications

非技术描述：最近，人们对下一代量子密码学产生了浓厚的兴趣，量子密码学是一种不受窃听的通信方法，可以实现不可破坏的安全数据共享。量子密码学基于纠缠光子的概念，纠缠光子是光的唯一耦合粒子。关于纠缠光子的重要性质是，当测量另一个光子的性质时，能够获得关于一个光子的知识。这种不寻常的行为是光子等量子粒子所特有的，也是安全量子信息技术的核心。然而，迄今为止，由于缺乏适当的材料系统、精密制造或光学表征方法，有效产生纠缠光子的光源尚未完全开发出来。该项目通过先进的光子材料设计和精确的纳米级量子点合成来克服这些挑战，其中纠缠光子被创造出来。项目活动还包括向本科生、人数不足的高中生和一般社区推广的教学努力，重点是人数不足的科学和技术学生。持续的本科生和研究生交叉训练以及新的跨学科课程开发影响着介观材料和量子科学界面的科学进步。技术描述：纠缠光子的产生是量子通信的基石，通过信道监控可以检测到光子波函数在测量或探测时的坍缩。然而，许多纠缠光子源是基于自发参数下转换的。自发发射过程是不确定的，一定程度的光子统计-无论是在贝尔不等式测量或断层扫描-仍然需要，导致长时间的计数和缓慢的安全密钥速率。本项目旨在通过展示基于混合量子点-纳米线异质结构的确定性纠缠光子源来解决这一挑战。该项目的第一部分旨在通过选择性区域外延展示用于确定性纠缠光子产生的混合量子点-纳米线异质结构。为了实现接近零的精细结构分裂，需要通过适当的生长技术仔细控制量子点的异质界面和几何形状。研究的第二部分旨在检查光子的相关性，并测量在介观固体实现中产生的纠缠光子的不可分辨性。该项目还将研究与教学教育和推广计划相结合，包括创新推广、本科生和研究生的培训和指导，以及一门关于量子通信设备物理学的新研究生课程。一些活动的例子包括举办暑期高中学生体验实验室工作，雇用本科生充分参与学术研究，以及开发新的研究生课程：量子通信介观材料。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Nontechnical description: Recently there has been intense interest in next-generation quantum cryptography, a communications method immune to eavesdropping, which enables unbreakable secure data sharing. Quantum cryptography is based on the concept of entangled photons, which are uniquely-coupled particles of light. The important property about entangled photons is the ability to gain knowledge about one photon when measuring the properties of the other photon. This uncommon behaviour is unique to quantum particles such as photons, and is at the core of secure quantum information technologies. To date, however, sources that efficiently produce entangled photons have not been fully developed due to lack of appropriate material systems, precision fabrication, or optical characterization approaches. This project overcomes these challenges through advanced photonic materials design and precise nanoscale synthesis of quantum dots in which entangled photons are created. The project activity also embraces the pedagogical efforts for outreach into the undergraduate, underrepresented, high-school and general community, with emphasis on underrepresented students in science and technology. Consistent cross-training of undergraduate and graduate students and new cross-disciplinary curricula development impact the scientific advances at the interface of mesoscopic materials and quantum sciences.Technical description: The generation of entangled photons is the cornerstone towards quantum communications, where the collapse of the photon wavefunction upon measurement or detection can be detected through channel monitoring. Much of the entangled photon sources, however, are based on spontaneous parametric downconversion. The spontaneous emission process is not deterministic and some degree of photon statistics - whether in Bell inequality measurements or tomography - is still needed, resulting in long-time counting and slow secure key rates. This project aims to tackle the challenge by demonstrating a deterministic entangled photon source based on a hybrid quantum dot-nanowire heterostructure. The first part of this project aims to demonstrate a hybrid quantum dot-nanowire heterostructure by selective area epitaxy for deterministic entangled photon generation. To achieve near-zero fine-structure splitting, the heterointerfaces and the geometry of quantum dots need to be carefully controlled by appropriate growth techniques. The second part of the research seeks to examine the photon correlation and measure the indistinguishability of the entangled photons generated in the mesoscopic solid-state implementation. The project also integrates the research with a pedagogical educational and outreach plan, including innovative outreach, training and mentoring of undergraduates and graduates, and a new graduate course on physics of quantum communication devices. Some examples of activities include hosting summer high school students to experience laboratory work, employing undergraduate students to fully participate in academic research, and developing a new graduate course: Mesoscopic Materials for Quantum Communications.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.