A closed-cycle, liquid helium cryocooler for next generation quantum light sources

利用光和物质的奇异量子力学特性的技术有望彻底改变我们处理和共享信息的方式。量子计算机可以利用叠加原理实现大规模并行性，并相应地加速当今难以解决的问题;量子通信可以使用海森堡的不确定关系来隐藏信息，以实现不可破解的密码。光学系统是量子技术的核心，特别是那些与长距离通信和干涉测量有关的技术。开发优化的量子光源，特别是单光子光源，对于它们的广泛应用和成功至关重要。 参量下转换是一种非线性光学过程，其中一个高能光子被分裂成一对较低能量的光子，是当今最常见的单光子和纠缠光子的来源。它具有一些不期望的特性，对许多量子技术的性能产生负面影响：例如，它具有固有的概率性，并且包含多光子发射。下一代量子光源需要克服这些限制。 取代下转换的有希望的系统可以广泛地描述为“单发射体”或人造原子。这些是量子系统，一旦被激发，可以发射一个且只有一个光子返回到它们的基态。我们的目标是利用嵌在纳米线和氮化硼片缺陷中的磷化铟砷量子点作为单发射极单光子源，开发下一代单光子源和纠缠光子源。这两种系统都必须冷却到低温，以抑制热噪声和窄光谱特性。我们将采用非线性光学技术来改变和塑造量子应用这些来源的光子的光谱特性。该提案要求为能够将这些样品冷却到4K的封闭循环液氦制冷机提供资金。封闭循环系统能够回收氦气，减少液氦费用，并延长运行时间，这对于多光子实验的预期长集成时间至关重要 拟议的研究将涉及3名博士生的全职工作，每年至少包括一个本科或合作工作学期。他们将获得丰富的经验和安全培训与国家的最先进的低温以及激光，光学和单光子探测。预计他们的工作将在顶级科学期刊上发表。

Technologies exploiting the exotic quantum mechanical properties of light and matter promise the revolutionize the way we process and share information. A quantum computers could exploit the Superposition Principle for massive parallelism and a corresponding quantum speed-up of problems that are intractable today; quantum communication can use Heisenberg's Uncertainty Relation to hide information for unbreakable cryptographic ciphers. Optical systems are central to quantum technologies, particularly those related to long-distance communication and interferometric metrology. Developing optimize quantum light sources, particularly single-photon sources, is crucial to their widespread application and success. Parametric down-conversion, a nonlinear optical process in which a high energy photon is split into a pair of lower energy photons, is the most common source of single and entangled photons today. It has some undesirable characteristics negatively impacting the performance of many quantum technologies: for example, it is inherently probabilistic and contains multiple photon emission. The next generation of quantum light sources needs to overcome these limitations. Promising systems to supersede downconversion can be broadly characterized as 'single emitters' or artificial atoms. These are quantum systems that, once excited, can emit one and only one photon to return to their ground state. We aim to exploit Indium Arsenide Phosphide quantum dots embedded in nanowires and defects in Boron Nitride sheets as single emitter single photon sources, to develop the next generation of single and entangled photon sources. Both of these systems must be cooled to cryogenic temperatures to suppress thermal noise and narrow spectral features. We will employ nonlinear optics techniques to shift and shape the spectral properties of the photons from these sources for quantum applications. This proposal requests funding for a closed-cycle liquid helium cryocooler capable of cooling these samples to 4K. The closed cycle system enables recycling of helium, reducing liquid helium expenses, and very long running times, essential for the expected long integration times of multiphoton experiments The proposed research would involve the full-time efforts of 3 PhD students and include at least one undergraduate or co-op work term each year. They will gain extensive experience and safety training with state-of-the-art cryogenics as well as lasers, optics, and single photon detection. It is anticipated that their work would be published in top-tier scientific journals.