'Double-slit' and multiple-path Interference studies from Rb excited and ionized by high-resolution laser radiation.

高分辨率激光辐射激发和电离铷的“双缝”和多路干涉研究。

• 批准号: EP/V027689/1
• 负责人: Andrew Murray
• 金额: $ 72.36万
• 依托单位: University of Manchester
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FV027689%2F1
• 关键词: Double; slit; multiple; path; Interference

The double-slit experiment using electrons to produce interference at a detector was voted as one of the 5 'most beautiful experiments in physics' by Physics World readers in 2002. Recent experiments in 2013 demonstrated that SINGLE electrons that were detected before the next electron was emitted also produce an interference pattern when the signal builds up over time. This convincingly shows individual electrons have both wave-like & particle-like character, as predicted by Richard Feynman in the early 1960's. Feynman thought such experiments would never be done, however advances in technology since then have now made this possible. The interference pattern arises since we do not know which slit the electron passes through. We assign a wavefunction to the electron, & the slits then define 2 possible pathways for the wave to travel from source to detector. The wavefronts beyond the slits then recombine at the detector, & the square of their sum gives the probability an electron is detected. If the peak of one wave meets the trough of another, the waves cancel & there is zero probability an electron will be detected at that position. By contrast, if two peaks or two troughs arrive at a point, there is then maximum probability an electron will be detected. An interference pattern is hence produced across the detector, which depends on how the waves recombine at any given point.In Manchester we recently invented a new type of 'double-slit' experiment in a single atom, where the 'slits' are replaced by atomic states 1 & 2 excited by lasers. The laser beam that excites state 1 also ionizes state 2, whereas the laser exciting state 2 ionizes state 1. There are then 2 pathways to ionization, & we do not know which was taken to produce the detected photoelectron. We again have to add the wavefunctions from each path to determine the outcome, leading to interference. The states (slits) can be turned on or off (effectively opening or closing individual slits) by selectively tuning & detuning the lasers & this allows us to determine the interference pattern.In the new experiments to be carried out in this proposal we will explore this process in much greater detail, by selecting different excited states & by using different laser polarizations. Our collaborators in Germany theoretically predict this will produce large changes to the ensuing pattern. A further prediction we will explore is that injection of a third laser beam can selectively control the interference. This new idea has no analogy in a conventional double-slit experiment & may find application in other areas where wavefunctions must be manipulated (e.g. quantum computing).There is no reason why these processes must be confined to single atoms & the second facet of this work will explore how laser excitation & ionization can be applied to arrays of atoms. We will first cool the atoms to close to absolute zero in a magneto-optical trap, before creating a periodic array of excited atoms using a standing-wave laser. The atoms will then be ionized by a second laser, set so that the de Broglie wavelength of the emerging photoelectrons is comparable in size to the dimensions of the array. Interference will once again occur, however now the summation is for waves from ALL sites from which the photoelectrons are born. The resulting yield then depends on both the individual atoms, as well as their position in the array. This is expected to be similar to the effect a diffraction grating has on light, however now the waves are for electrons rather than photons. By altering the properties of the lasers we can 'shape' the grating in different ways, which will change the electron distribution that is produced. Initial models from our collaborators support these ideas & experiments are needed to test & refine the models. This work could find application in electron diffraction studies of surfaces & for controlling the injection of electrons into particle accelerators.

使用电子在检测器上产生干扰的双缝实验被2002年物理世界读者投票为5个“物理学中最美丽的实验”之一。2013年的最新实验表明，在信号随着时间的推移累积时，在发出下一个电子之前检测到的单个电子也会产生一种干扰模式。这令人信服地表明，正如1960年代初期的理查德·费曼（Richard Feynman）所预测的那样，单个电子既具有波浪状和粒子状特征。 Feynman认为这种实验将永远不会做，但是从那时起，技术的进步现在就使这成为可能。由于我们不知道电子通过了哪个缝隙，因此出现了干扰模式。我们为电子分配了一个波函数，然后缝隙定义了2个可能的途径，使波从源到检测器传播。然后在缝隙以上的波前在检测器处重新组合，其总和给出了检测到电子的概率。如果一个波的峰值符合另一波的槽，则波取消且概率为零，将在该位置检测到电子。相比之下，如果两个峰或两个槽到达一个点，则将检测到电子的最大概率。因此，在整个检测器上产生了一种干扰模式，这取决于在任何给定点的波如何重组。在曼彻斯特，我们最近在一个原子中发明了一种新型的“双缝”实验，在该原子中，“缝隙”被激光器激发的原子状态1和2所代替。激发状态1的激光束也使状态2离子2，而激光刺激状态2离子化状态1。然后有2种电离途径，并且我们不知道哪些是为了产生检测到的光电子。我们再次必须从每个路径中添加波形以确定结果，从而导致干扰。可以通过选择性调整和失调激光器来打开或关闭状态（缝隙）（有效地打开或关闭单个缝隙），这使我们能够确定干扰模式。在本提案中可以进行新实验，我们将通过更详细地探索此过程，通过使用不同的激发状态和使用不同的激光极化来详细介绍此过程。从理论上讲，我们在德国的合作者预测，这将为随后的模式带来很大的变化。我们将探讨的另一个预测是，注入第三激光束可以选择性地控制干扰。这个新想法在常规的双缝实验中没有类比，并且可能在必须操纵波源的其他领域（例如量子计算）。没有理由必须将这些过程局限于单个原子，而这项工作的第二个方面将探索如何应用激光激发和电离，以应用于Atom attoms的阵列。首先，我们将在磁光陷阱中冷却原子以接近绝对零，然后使用站立式激光器创建周期性的激发原子。然后将通过第二激光将原子电离，以使新兴光电子的DE Broglie波长与阵列的尺寸相当。干扰将再次发生，但是现在总结是来自光电子诞生的所有地点的波浪。然后产生的产量取决于两个个体原子以及它们在阵列中的位置。这有望与衍射光栅对光的影响相似，但是现在波浪是针对电子而不是光子的。通过改变激光器的性能，我们可以以不同的方式“塑造”光栅，这将改变产生的电子分布。我们的合作者的初始模型支持这些想法和实验来测试和完善模型。这项工作可以在表面的电子衍射研究中找到应用，并控制电子将电子注射到粒子加速器中。

项目成果

Laser-atom interaction simulator derived from quantum electrodynamics

基于量子电动力学的激光-原子相互作用模拟器

• DOI: 10.1103/physreva.105.053117
• 发表时间: 2022
• 期刊: Physical Review A
• 影响因子: 2.9
• 作者: Patel M

Measurements of the Kr (e, 2e) differential cross section in the perpendicular plane, from 2 eV to 120 eV above the ionization threshold

垂直平面中 Kr (e, 2e) 微分截面的测量，电离阈值以上 2 eV 至 120 eV

• DOI: 10.48550/arxiv.2304.00956
• 发表时间: 2023
• 作者: Murray A

A low-cost and reliable laser shutter interlock using a software-command interface

使用软件命令接口的低成本且可靠的激光快门联锁

• DOI: 10.1088/1361-6501/ac8ca7
• 发表时间: 2022
• 期刊: Measurement Science and Technology
• 影响因子: 2.4
• 作者: Rogers J

Measurements of the Kr ( e , 2 e ) differential cross section in the perpendicular plane from 2 to 120 eV above the ionization threshold

在高于电离阈值 2 至 120 eV 的垂直平面内测量 Kr ( e , 2 e ) 微分截面

• DOI: 10.1103/physreva.107.062807
• 发表时间: 2023
• 期刊: Physical Review A
• 影响因子: 2.9
• 作者: Murray A

An undergraduate physics experiment to measure the frequency-dependent impedance of inductors using an Anderson bridge

使用安德森电桥测量电感器频率相关阻抗的本科物理实验

• DOI: 10.1119/5.0148114
• 发表时间: 2023
• 期刊: American Journal of Physics
• 影响因子: 0.9
• 作者: Murray A