Experimental Study of Quantum Jumps with a Single Trapped Ion

University Of Washington, Seattle WA

Investigators

Abstract

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.