Experimental Study of Quantum Jumps with a Single Trapped Ion

University Of Washington, Seattle WA

Investigators

Abstract

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.