Noise in mesoscopic quantum systems

介观量子系统中的噪声

• 批准号: RGPIN-2016-04163
• 负责人: Marzlin, KarlPeter
• 金额: $ 1.6万
• 依托单位: St. Francis Xavier University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=708123
• 关键词: Noise; mesoscopic; quantum; systems

Noise, i.e., fluctuations of an observable due to external factors, is a phenomenon that affects all measurements. Studying its effects is particularly important for quantum systems because of the fragile nature of quantum correlations. Usually noise is considered detrimental because it may reduce the quality of experimental results. However, it can also play a vital role in triggering processes such as chemical reactions. Furthermore, noise can be manipulated by changing the temperature of a system's environment, or by more advanced techniques. One example of such a technique is the improved resolution of gravitational wave detectors by using squeezed states of light instead of ordinary laser beams. In this project we will study noise and its implications for three rather different systems: surface-enhanced stimulated Raman spectroscopy of molecules (SESRS), spin relaxation in single-molecule magnets (SMM), and the Purcell filter in circuit Quantum Electrodynamics (cQED). The SESRS system consists of a molecule attached to a gold nano-particle, which interacts with two laser pulses of different frequency. A SMM consists of a single molecular metal compound that displays magnetic hysteresis, and the cQED system of the third project consists of a micrometer-sized electric circuit that includes superconducting elements. The overarching element of all three systems is the noise mechanism, which follows surprisingly similar principles. In all three systems, noise is introduced through a finite number of damped oscillators. In SESRS and SSM, these oscillations are formed by nuclear vibrations in a molecule, while, in cQED, they correspond to oscillating microwave fields in a resonator. Working on such different systems will enable us to transfer ideas and methods between all systems. This project has two goals: (i) manipulating noise to improve a system, and (ii) characterizing the noise dependence on the environment of the system. Goal (i) aims at improving the desired signal of a system by changing the way it interacts with the noise. The Purcell filter is an example of such a change: by adding additional microwave resonators, noise can be suppressed in a particular frequency range. In a similar way, molecular noise could be manipulated to increase the relaxation time in SMM or the radiation intensity in SESRS. Goal (ii) aims at extracting information about the environment of a molecule from its spectrum. In this way, radiation emitted by a molecule could be used to probe the general structure of the material surrounding it.

噪声，即由于外部因素引起的可观测物的波动，是一种影响所有测量的现象。由于量子关联的脆弱性质，研究其效应对量子系统尤为重要。通常，噪声被认为是有害的，因为它可能会降低实验结果的质量。然而，它也可以在触发化学反应等过程中发挥至关重要的作用。此外，可以通过改变系统环境的温度或通过更先进的技术来控制噪音。这种技术的一个例子是通过使用光的压缩状态而不是普通的激光来提高引力波探测器的分辨率。 在这个项目中，我们将研究噪声及其对三个相当不同的系统的影响：表面增强受激拉曼分子光谱(SESRS)、单分子磁体中的自旋弛豫(SMM)和电路中的珀塞尔滤波器量子电动力学(CQED)。SESRS系统由附着在金纳米粒子上的分子组成，金纳米粒子与两个不同频率的激光脉冲相互作用。SMM由显示磁滞的单分子金属化合物组成，第三个项目的cQED系统由微米大小的电路组成，其中包括超导元件。这三个系统最重要的元素是噪音机制，它遵循着惊人的相似原理。在这三个系统中，噪声都是通过有限数量的衰减振荡器引入的。在SESRS和SSM中，这些振荡是由分子中的核振动形成的，而在cQED中，它们对应于谐振器中的振荡微波场。在这样不同的系统上工作将使我们能够在所有系统之间传递思想和方法。 这个项目有两个目标：(I)控制噪声以改进系统，以及(Ii)表征噪声对系统环境的依赖。目标(I)旨在通过改变系统与噪声相互作用的方式来改善系统的期望信号。珀塞尔滤波器就是这种变化的一个例子：通过增加额外的微波谐振器，可以在特定的频率范围内抑制噪声。同样，可以通过操纵分子噪声来增加SMM中的驰豫时间或SESRS中的辐射强度。目标(2)旨在从分子的光谱中提取有关其环境的信息。通过这种方式，分子发出的辐射可以用来探测其周围物质的一般结构。