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成就之一。如今进入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，这些技术实际使用了量子理论的强大概念和思想。然而，即使经过一个多世纪的科学研究，这些概念和想法中的许多仍然没有完全被理解。一个这样的概念是波函数的崩溃。根据量子力学，原子等微观物体的行为像波一样，它们可以以所谓的叠加态存在，就像著名的薛定谔猫一样，它既死又活。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。以薛定谔的猫为例，当我们打开盒子时，我们发现一只猫是可爱的或活的，而不是同时存在。这个项目的目的是研究单个原子在不同量子态之间经历“量子跳跃”时量子力学崩塌的细节。单个原子将被电磁场捕获，并被激光控制以诱导量子坍塌，这将通过观察原子发出的单光子来进行研究。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。该奖项将支持两名研究生和本科生的研究，他们将为未来的量子工作做好准备。1913年，尼尔斯·玻尔首次提出量子跳跃的理论，但直到1986年，汉斯·德梅尔特的团队才通过实验观察到了量子跳跃。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，这项实验是因为超导量子比特发出的几乎每一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类似水平的单光子探测，该离子陷阱结合了一个深抛物面反射镜，覆盖了离子周围95%以上的固体角度。这将使得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，只受离子的散射率限制，并有可能跟踪和控制波函数坍塌的动力学。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 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.