Collaborative research: Understanding and Engineering the Timing Precision of Superconducting Nanowire Single Photon Detectors

合作研究：理解和设计超导纳米线单光子探测器的定时精度

• 批准号: 1509486
• 负责人: Karl Berggren
• 金额: $ 38.06万
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-06-15 至 2019-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1509486&HistoricalAwards=false
• 关键词: Collaborative; research; Understanding; Engineering; Timing

Title: Understanding and Engineering the Timing Precision of Superconducting Nanowire Single Photon DetectorsSuperconducting electronics and radiation sensors are exceptional for their speed of operation and precision of timing. As a result, they find application in critical niches such as space communications, metrology, sensing, and computation. The performance of these devices thus sets the limit of what can be achieved in these domains. One type of superconducting detector in particular has demonstrated high speed and timing precision: the superconducting nanowire single photon detector. This type of detector is able to detect the arrival of the smallest amounts of light possible, a single photon. As a result of its excellent speed and precision characteristics, it has found application in a wide variety of areas. For example, quantum key distribution, the secure communications method of the future, crucially relies on timing precision of photon detection in order to guarantee security. In a related field, emerging quantum computing thrusts such as those taking place on photonic integrated circuits rely on the precise detection of single photons. Unfortunately, although the speed limitations of the superconducting nanowire single photodetector are well understood, we do not yet understand what limits timing precision (typically referred to as "jitter"), and thus cannot yet engineer improvement. Many theories have been developed that can explain how these superconducting nanowires function. However, none of these theories can justify the jitter seen in these detectors. In this work, we will investigate the fundamental limits of jitter in superconducting nanowire single-photon detectors, and thus enable improvements in a wide array of application areas. For example, communication data rates depend directly on the jitter because the standard low- power digital communication protocol, pulse-position-modulation, uses timing precision to enhance the data rate. By investigating and characterizing possible sources of timing jitter in these detectors, this work will directly increase the impact of the relevant applications in industry, space, and defense.Although superconducting nanowires have been studied since the 1970s and have been used as radiation sensors for over 13 years, their picosecond-time-scale dynamics are still not fully understood. Early attempts to explain the timing dynamics in superconducting nanowire single photon detectors focused on possible microscopic origins. In the field of radiation sensors based on superconducting nanowires, some theories related these picosecond-time-scale effects to environmental causes and others to processes intrinsic to the physics of the superconducting nanowires. For example, the hotspot model of the detection mechanism was suggested to explain the time delay between the photon arrival and voltage response as a function of number of incident photons at two different bias currents, but fitting to a theoretical model of gap suppression time was poor and no mention of jitter was made. Later, phase slip centers were purported as the mechanism for the initial hotspot creation but again, no substantive connection to jitter came about from those analyses. In this project, we will probe commonly accepted theories in the field as well as unexplored sources of jitter using both numerical and experimental approaches. We have identified several key components of the nanowire operation that we consider likely sources of jitter: (1) nanowire self-resonance; (2) trapping of vortices; and (3) stochastic elements in the microscopic physics of the hotspot. We intend to characterize the jitter contributions of each of these possible sources, and design modified devices that can reduce these contributions to jitter.

标题：理解和工程超导纳米线单光子检测器的时机精确度，其操作速度和计时速度非常出色。结果，他们发现在关键的小众市场中的应用，例如空间通信，计量，传感和计算。因此，这些设备的性能设置了在这些域中可以实现的限制。尤其是一种超导检测器的一种类型表明，高速和时机精度：超导纳米线单光子检测器。 这种类型的检测器能够检测最小的光（单个光子）的到达。由于其出色的速度和精确特征，它发现了在各种领域的应用。例如，量子密钥分布（未来的安全通信方法）至关重要地依赖于光子检测的时序精度，以保证安全性。在相关的领域中，新兴的量子计算推力（例如在光子综合电路上发生的量子）依赖于单个光子的精确检测。不幸的是，尽管对超导纳米线的单个光电探测器的速度限制有充分的理解，但我们尚不了解限制的时序精度（通常称为“抖动”），因此尚无法改进。已经开发了许多理论，可以解释这些超导纳米线的功能。但是，这些理论都无法证明这些探测器中看到的抖动是合理的。在这项工作中，我们将调查超导纳米式单光子检测器中抖动的基本限制，从而可以改善各种应用领域。 例如，通信数据速率直接取决于抖动，因为标准的低功率数字通信协议（脉冲位置调制）使用时序精度来提高数据速率。通过调查和表征这些探测器中可能的计时抖动的可能来源，这项工作将直接增加相关应用在行业，空间和防御中的影响。尽管自1970年代以来就已经研究了超导纳米线，并且已被用作辐射传感器，并已将其用作13年以上的辐射传感器，但他们的PicoSecteptime-scale-scale Dynamics仍未完全理解。早期尝试解释超导纳米线单光子探测器的时序动态，该检测器集中于可能的显微镜起源。在基于超导纳米线的辐射传感器领域中，某些理论将这些比较时间尺度的效应与环境原因相关，而其他理论则与超导纳米线的物理学固有的处理。例如，提出了检测机制的热点模型来解释光子到达和电压响应之间的时间延迟，这是两种不同的偏置电流处入射光子数量的函数，但适合于间隙抑制时间的理论模型很差，没有提及抖动。后来，据称，相位滑动中心是最初的热点创建的机制，但同样，这些分析没有与抖动的实质性联系。在这个项目中，我们将使用数值和实验方法探测该领域中通常接受的理论以及未开发的抖动来源。我们已经确定了纳米线操作的几个关键组成部分，我们考虑了可能的抖动来源：（1）纳米线自我谐振； （2）涡旋捕获； （3）热点的微观物理学中的随机元素。我们打算表征每种可能来源的抖动贡献，并设计可以减少这些抖动这些贡献的修改设备。