CAREER: Quantum Spin-Optomechanics of Optically Levitated Nanodiamonds

职业：光悬浮纳米金刚石的量子自旋光力学

• 批准号: 1555035
• 负责人: Tongcang Li
• 金额: $ 45.78万
• 依托单位: Purdue University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-05-01 至 2021-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1555035&HistoricalAwards=false
• 关键词: CAREER; Quantum; Spin; Optomechanics; Optically

Very small particles can behave in ways that are contrary to common sense. For example, an electron (one of the particles that make up atoms) can be at multiple locations at the same time and can tunnel through a barrier--something forbidden by the classical laws of physics. The theory that explains these counterintuitive behaviors of small particles is "quantum mechanics". This CAREER project will investigate the possibility of making quantum mechanics appear manifest in larger, more macroscopic, systems. In specific, the project will investigate how to couple the spin of an electron to the motion of a nanoparticle (containing millions of atoms). The nanoparticle will be levitated by a laser beam in vacuum to avoid perturbations from the environment. This system should serve as a very sensitive force detector with many applications. It may enable other experiments to study the conflict between general relativity and quantum mechanics, a longstanding problem in physics. The research will be integrated with several related educational activities, including direct training of graduate and undergraduate students participating in the research, and conducting inquiry workshops about infrared light for middle and high school teachers and students. Infrared light is not visible to human eyes, but plays a crucial role in global warming and fiber-optic communication. In the present work, infrared light will be used to levitate nanoparticles in vacuum. After doing hands-on experiments with infrared light in the workshop, teachers will be able to take their apparatus for use in their classrooms.In more technical detail, this research project will develop a system that combines the advantages of both trapped atoms and conventional optomechanical systems for studying macroscopic quantum mechanics: an optically levitated nanodiamond with a built-in nitrogen-vacancy (NV) center. In some ways, this system can be considered to be an "artificial atom" with a very large mass. The electron spin of the NV center can be coupled to the motion of the nanodiamond with a magnetic field gradient. This coupling can be used to create large quantum spatial superposition states of the nanodiamond, which will lead to the development of a nanoparticle matter-wave interferometer for fundamental tests of quantum mechanics in unexplored parameter regimes. The main focus of this CAREER project will be to experimentally study the coupling between an NV electron spin and both the center-of-mass motion and the rotation of an optically levitated nanodiamond. The motion of the levitated nanodiamond will be cooled to near quantum ground state by active feedback cooling. The NV electron spin will be used to sense and manipulate the motion of the nanodiamond. It will also be used to measure the internal temperature of the levitated nanodiamond which affects the quantum coherence time.

非常小的颗粒的行为可能会违反常识。例如，电子（构成原子的粒子之一）可以同时位于多个位置，并且可以穿过势垒——这是经典物理定律所禁止的。解释小粒子这些反直觉行为的理论是“量子力学”。这个职业项目将研究使量子力学在更大、更宏观的系统中显现出来的可能性。 具体来说，该项目将研究如何将电子的自旋与纳米粒子（包含数百万个原子）的运动耦合起来。纳米粒子将在真空中被激光束悬浮，以避免受到环境的干扰。该系统应作为具有多种应用的非常灵敏的力检测器。 它可能使其他实验能够研究广义相对论和量子力学之间的冲突，这是物理学中一个长期存在的问题。该研究将与多项相关教育活动相结合，包括直接培训参与研究的研究生和本科生，以及为初中和高中教师和学生举办有关红外光的探究研讨会。红外光是人眼看不见的，但在全球变暖和光纤通信中起着至关重要的作用。 在目前的工作中，红外光将用于在真空中悬浮纳米颗粒。在研讨会上用红外光进行动手实验后，教师将能够在课堂上使用他们的设备。在更多技术细节上，该研究项目将开发一种结合了捕获原子和传统光机械系统的优点来研究宏观量子力学的系统：一种具有内置氮空位（NV）中心的光悬浮纳米金刚石。在某些方面，这个系统可以被认为是一个质量非常大的“人造原子”。 NV中心的电子自旋可以通过磁场梯度与纳米金刚石的运动耦合。这种耦合可用于创建纳米金刚石的大量子空间叠加态，这将导致纳米粒子物质波干涉仪的开发，用于在未探索的参数范围内进行量子力学的基本测试。该职业项目的主要重点将是通过实验研究 NV 电子自旋与光学悬浮纳米金刚石的质心运动和旋转之间的耦合。悬浮纳米金刚石的运动将通过主动反馈冷却被冷却到接近量子基态。 NV 电子自旋将用于感测和操纵纳米金刚石的运动。它还将用于测量悬浮纳米金刚石的内部温度，该温度会影响量子相干时间。