Experimental Study of Quantum Jumps with a Single Trapped Ion

量子理论可能是20世纪科学最重要的发展和胜利之一。在21世纪，随着量子计算和其他量子技术的出现，“第二次量子革命”正在进行，这些技术将量子理论的强大概念和思想付诸实践。然而，即使经过了一个多世纪的科学研究，这些概念和思想中的许多仍然没有被完全理解。其中一个概念就是波函数的坍缩。根据量子力学，像原子这样的微观物体的行为就像波，它们可以以所谓的叠加态存在，就像著名的薛定谔的猫一样，它同时是死的和活的。然而，根据量子力学，这些叠加态是无法被观察到的：当被观察到时，叠加态“坍缩”到其中一种状态。以薛定谔的猫为例，当我们打开盒子时，我们发现一只猫要么是亲爱的，要么是活着的，而不是两者同时存在。该项目旨在研究单个原子在不同量子态之间经历“量子跃迁”时量子力学坍缩的细节。单个原子将被电磁场捕获，并用激光控制来诱导量子坍缩，这将通过观察原子发射的单个光子来研究。理解量子坍缩的本质对于量子力学作为理论的基础，以及量子计算和量子信息的非常实际的方面都很重要。量子计算和量子通信等量子技术有望提高计算速度，改善信息安全，并为能量转换、电子和生物医学应用开发更好的材料。该奖项将支持两名研究生研究人员以及本科生的研究，他们将接受未来量子就绪劳动力的培训。1913年，尼尔斯·玻尔首次提出量子跃迁理论，但直到1986年，汉斯·德梅尔特的团队才通过实验观察到量子跃迁。在最初的实验中，跳跃表现为单个被捕获的激光冷却离子从“亮”状态到“暗”状态的瞬时转变，这是由光子计数探测器测量的。最近对超导电路制造的人造原子的量子跃迁的观察，使耶鲁大学的研究人员能够在一个实验中“捕捉”和“逆转”这种跃迁，这是因为超导量子比特发射的几乎每一个光子都被探测到了。该项目计划利用一种新型离子阱实现类似水平的单光子探测，该离子阱包含一个深抛物面镜，覆盖离子周围95%以上的立体角。这将使在纳秒时间尺度上观察量子跃迁成为可能，仅受离子的光散射率的限制，在一个没有耗散的系统中，有可能跟踪和控制波函数坍缩的动力学。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Quantum theory is perhaps one of the most important developments and triumphs of 20th century science. Now in the 21st century, the “second quantum revolution” is underway with the advent of quantum computing and other quantum technologies that make practical use of the powerful concepts and ideas of quantum theory. Yet, even after more than a century of scientific research, many of these concepts and ideas remain incompletely understood. One such concept is the collapse of the wave function. According to quantum mechanics, microscopic objects such as atoms behave like waves, and they can exist in so called superposition states, just like the famous Schrodinger’s cat 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. Using the Schrodinger’s cat example, when we open the box, we find a cat that is dear OR alive, not both at the same time. This project aims to study the details of quantum mechanical collapse using single atoms as they undergo “quantum jumps” between different quantum states. Single atoms will be trapped by electromagnetic fields and controlled with lasers to induce quantum collapse, which will be studied by observing single photons that the atoms emit. 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. The award will support research of two graduate student researchers, as well as undergraduate students who will be trained for the future quantum-ready workforce.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 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 similar level of single photon detection from a single trapped ion using a novel ion trap that incorporates a deep parabolic mirror covering more than 95% of the solid angle around the ion. This will enable observing of the quantum jumps at the nanosecond time scale, limited only by the scattering rate of light by the ion, 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.