Quantum Interface between Gamma-Photons - Nuclear Ensembles

基本粒子或“量子”光的波长约为500纳米(不到百万分之一英寸)。对这些光子与原子内部电子相互作用的研究导致了激光、原子钟、超灵敏微型磁力计等设备的发展。本项目的目标是将这些研究扩展到波长更短的光子：短10,000到100,000倍。这些肉眼看不见的光子开始进入被称为“伽马光子”或“伽马射线”的区域。这些高能光子与原子核相互作用，而不是与原子内部的电子相互作用。伽马光子在应用中可能比传统(光学)光子更好的一些原因是，它们更容易被检测到，它们可以聚焦到更小的光点(最终受到光子波长的限制)，而且它们原则上可以帮助更快地处理信息，因为它们的频率更高。一个问题是，目前它们的生产非常困难，成本也很高，而且很难精确地控制，因为传统的光学透镜和反射镜不能在如此短的波长下工作。这项工作旨在通过实验和理论工作推动高度受控的紧凑型(桌面)伽马光子源的发展。实际上，这项工作试图将“量子光学”领域扩展到接近伽马射线区域的波长。如果成功，这项工作可能会在量子信息科学、光谱学、显微镜、计量学和传感器等领域得到应用。拟议的理论和实验联合研究计划将在实验和理论量子伽马光学的新兴领域以及相关(更一般的)实验技术、分析方法和数值模拟方面为研究生和本科生提供培训。该项目专注于通过改变实验室参考系中核跃迁的共振频率来相干控制伽马光子与核系综的相互作用的方法的实验和理论发展。这种变化是通过与光子通过的固体精确振动相关的多普勒频移实现的。它与预告单光子源一起使用，这是通过钴-57的自然放射性衰变，基本上同时发射122keV和14.4keV的两个光子提供的。与电子跃迁相比，核跃迁的优点是在室温下(由于核子的大质量和小尺寸，屏蔽环境，以及穆斯堡尔效应的无反冲吸收)，它们在块状固体中具有窄的、寿命展宽的谱线宽度。这导致了光子与核系综间的数量级更强的相互作用。然而，由于在所需的短波长范围内缺乏明亮的相干源和高精细度的谐振器，进展受到限制。本工作的基础是首席科学家最近实现了14.4keV范围内具有相干特性的台式超短光子源，并展示了有效控制单伽马光子波形(F.Vagizov等人，《自然》，第508卷|2014年4月3日，第80页)。将探索目前开发的该技术的技术和基本限制，并将开发产生短强度脉冲和单伽马光子整形的新技术。受控单光子波形在量子信息科学领域的应用将被探索。

The elementary particles or "quanta" of light have a wavelength of about 500 nanometers (less than 20 millionths of an inch). The study of the interaction of these photons with the electrons inside atoms led to development of devices such as lasers, atomic clocks, supersensitive miniature magnetometers, etc. The goal of the present project is to extend these studies to photons of much shorter wavelengths: 10,000 to 100,000 times shorter. These photons, invisible to the naked eye, begin to enter the regime where they are known as "gamma-photons" or "gamma-rays." Rather than interacting with the electrons inside atoms, these high energy photons interact with the nucleus of the atom. Some of the reasons gamma-photons might be better than conventional (optical) photons for applications is that they can be detected more easily, they can be focused to much smaller spots (ultimately limited by the wavelength of the photon), and they can in principle help process information more quickly because of their higher frequencies. A problem is that they are currently very difficult and expensive to produce and hard to control precisely because conventional optical lenses and mirrors do not work at such short wavelengths. This work seeks to advance the development of compact ("table-top") sources of highly controlled gamma-photons, both through experiments and theoretical work. In effect, this work seeks to extend the field of "quantum optics" to wavelengths approaching the gamma-ray regime. If successful, the work may find applications in the areas of quantum information science, spectroscopy, microscopy, metrology, and sensors. The proposed joint theoretical and experimental research program will provide training for graduate and undergraduate students in the emerging field of the experimental and theoretical quantum gamma-optics as well as in the related (and more general) experimental techniques, analytical methods, and numerical modeling.The project is focused on the experimental and theoretical development of methods to coherently control the interaction of gamma-photons with nuclear ensembles via the variation of the resonant frequency of the nuclear transition in the laboratory reference frame. This variation is achieved via the Doppler shift associated with precisely vibrating the solid through which the photon passes. This is used in conjunction with a source of heralded single photons provided by the essentially simultaneous emission of two photons at 122 keV and 14.4 keV via the natural radioactive decay of Cobalt-57. The advantages of nuclear transitions over electronic transitions is that they have narrow, lifetime-broadened spectral linewidths in bulk solids at room temperature (due to the large mass and small size of nucleons, shielding from the environment, and recoilless absorption due to the Mossbauer effect). This results in orders-of-magnitude stronger interaction of the photons with the nuclear ensemble. Progress has been limited, however, by the absence of bright coherent sources and high finesse resonators in the desired short wavelength range. The present work is based on the lead scientist's recent realization of a table-top source of ultra-short photon sources in the 14.4 keV range with coherent properties, as well as the demonstration of efficient control of single gamma-photon waveforms (F. Vagizov et al., Nature, vol. 508| 3 April 2014, p. 80). The technical and fundamental limitations of the technique as presently developed will be explored and new techniques for the production of short intense pulses and single gamma-photon shaping will be developed. Applications for the controlled single-photon waveforms will be explored in the areas of quantum information science.