Experimental Study of Quantum Jumps with a Single Trapped Ion

量子理论也许是世纪科学最重要的发展和成就之一。现在，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”正在进行中，这些技术实际上利用了量子理论的强大概念和思想。然而，即使经过世纪的科学研究，这些概念和想法中的许多仍然没有完全理解。其中一个概念是波函数的坍缩。根据量子力学，原子等微观物体的行为就像波一样，它们可以存在于所谓的叠加态中，就像著名的薛定谔的猫同时是死的和活的。然而，根据量子力学，这些叠加是无法观察到的：当进行观察时，叠加“坍缩”到其中一个状态。以薛定谔的猫为例，当我们打开盒子时，我们会发现一只猫是可爱的还是活着的，而不是两者同时存在。该项目旨在研究使用单个原子在不同量子态之间进行“量子跳跃”时量子力学坍缩的细节。单原子将被电磁场捕获，并用激光控制以诱导量子坍缩，这将通过观察原子发射的单光子来研究。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实际方面都很重要。量子计算和量子通信等量子技术有望提高计算速度，改善信息安全性，并为能源转换，电子和生物医学应用开发更好的材料。该奖项将资助两名研究生研究人员的研究，以及将接受未来量子准备工作培训的本科生。量子跃迁最早由尼尔斯·玻尔于1913年提出理论，但直到1986年，汉斯·德梅尔特的小组才在实验中观察到它们。在最初的实验中，跳跃表现为一个被捕获的激光冷却离子从“亮”状态到“暗”状态的瞬时跃迁，这是由光子计数探测器测量的。最近对超导电路构建的人造原子中的量子跳跃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”跳跃，该实验是由超导量子比特发射的几乎每一个光子都被检测到的事实实现的。该项目计划使用一种新型的离子阱从单个捕获离子实现类似水平的单光子检测，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测量子跃迁成为可能，而这一时间尺度仅受离子对光的散射率的限制，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NSF的法定使命，并通过使用基金会的智力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.