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察到的波动，是一种影响所有测量结果的现象。由于量子相关性的脆弱性质，研究其影响对于量子系统尤为重要。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。但是，它在触发化学反应等过程中也可以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更高级技术来操纵噪声。这种技术的一个例子是通过使用挤压光态而不是普通的激光束改善了重力波检测器的分辨率。 在这个项目中，我们将研究噪声及其对三个较不同的系统的影响：表面增强的刺激分子的拉曼光谱（SESR），单分子磁体（SMM）中的自旋松弛以及电路量子电动力学（CQED）中的Purcell滤波器。 SESRS系统由连接到金纳米颗粒的分子组成，该分子与两个不同频率的激光脉冲相互作用。 SMM由一种显示磁性磁滞的单个分子金属化合物组成，第三个项目的CQED系统由千分尺尺寸的电路组成，其中包括超导元件。这三个系统的总体元素是噪声机制，噪声机制遵循出人意料的相似原理。在所有三个系统中，噪声都是通过有限数量的阻尼振荡器引入的。在SESR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微波磁场。在如此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。 该项目有两个目标：（i）操纵噪声以改善系统，以及（ii）表征对系统环境的噪声依赖性。 Goal (i) aims at improving the desired signal of a system by changing the way it interacts with the noise. purcell滤波器是这种更改的示例：通过添加其他微波谐振器，可以在特定的频率范围内抑制噪声。以类似的方式，可以操纵分子噪声，以增加SMM中的松弛时间或SESR中的辐射强度。目标（ii）旨在从其光谱中提取有关分子环境的信息。这样，可以使用分子发出的辐射来探测其周围材料的一般结构。