Experimental Study of Quantum Jumps with a Single Trapped Ion

量子理论成为20世纪科学最重要的发展和成就之一。目前，随着量子计算等量子技术的出现，第二次量子革命正在进行中。然而，量子理论的许多概念和想法仍然神秘或鲜为人知。其中一个概念就是所谓的“波函数崩塌”。根据量子力学，原子等微观物体的行为就像波，它们可以同时存在于两种状态的叠加中。这就像盒子里著名的薛定谔的猫，既死了又活了。然而，根据量子力学，这些叠加是不能观察到的：当进行观察时，叠加“坍塌”到其中一种状态。当我们打开盒子时，我们看到的是一只死了或活着的猫，而不是同时看到两者。该项目旨在使用单原子研究量子力学崩塌的微小细节，单原子是一些最原始的量子粒子。单个原子将被电磁场捕获，并用激光控制，以引发量子坍塌，并了解更多关于它的性质。理解量子崩塌的本质对于量子力学作为一种理论的基础，以及量子计算和量子信息的非常实用的方面都是重要的。量子计算和量子通信等量子技术有望提高计算速度，提高信息安全性，并为能源转换、电子和生物医学应用开发更好的材料。1913年，尼尔斯·玻尔首次提出了量子跳跃的理论，但直到1986年，汉斯·德梅尔特的团队才在实验中观察到了量子跳跃。在最初的实验中，跳跃表现为由光子计数探测器测量的单个被捕获的、激光冷却的离子从“亮”状态到“暗”状态的瞬间转变。最近对超导电路中人造原子的量子跳跃的观测使耶鲁大学的研究人员能够在一项实验中“捕捉”和“反转”量子跳跃，这项实验之所以能够实现，是因为超导量子比特发出的几乎每个光子都被探测到了。该项目计划使用一种新型的离子陷阱实现相同或更高水平的单光子探测，该离子陷阱包含一个覆盖离子周围90%以上固体角度的椭圆镜。这将使在一个没有耗散的系统中在纳秒时间尺度上观察量子跳跃成为可能，并有可能跟踪和控制波函数崩溃的动力学。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Quantum theory became one of the most important developments and triumphs of the 20th century science. Currently, the “second quantum revolution” is underway with the advent of quantum computing and other quantum technologies. Yet, many concepts and ideas of quantum theory remain mysterious or poorly understood. One such concept is the so-called "collapse of the wave function." According to quantum mechanics, microscopic objects such as atoms behave like waves, and they can exist in superpositions of two states at once. This is like the famous Schrodinger’s cat in the box that is both dead AND alive at the same time. However, according to quantum mechanics, these superpositions cannot be observed: when an observation is made, the superposition “collapses” to one of the states. When we open the box, we observe a cat that is dead OR alive, not both at the same time. This project aims to study the minute details of quantum mechanical collapse using single atoms, some of the most pristine quantum particles. Single atoms will be trapped by electromagnetic fields and controlled with lasers to incite quantum collapse and learn more about its properties. Understanding the nature of quantum collapse is important both for the foundations of quantum mechanics as a theory, and for the very practical aspects of quantum computing and quantum information. Quantum technologies such as quantum computing and quantum communications promise faster computing speed, improved information security, and development of better materials for energy conversion, electronics, and biomedical applications. Quantum jumps were first theorized in 1913 by Niels Bohr, but it wasn’t until 1986 that they were observed experimentally by Hans Dehmelt’s group. In the original experiment, the jumps manifested themselves as instantaneous transitions of a single trapped, laser-cooled ion from the “bright” state to the “dark” state as measured by a photon-counting detector. More recent observations of quantum jumps in artificial atoms built from superconducting circuits allowed the researchers at Yale to “catch” and “reverse” the jumps in an experiment that was enabled by the fact that nearly every single photon emitted by the superconducting qubit was detected. This project plans to achieve the same or higher level of single photon detection from a single trapped ion using a novel ion trap that incorporates an elliptical mirror covering more than 90% of the solid angle around the ion. This will enable observing of the quantum jumps at the nanosecond time scale in a system that is free from dissipation, with the possibility to track and control the dynamics of the wave function collapse.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.