This project will demonstrate laser cooling and optical trapping of an atomic species with a very complex internal structure, the rare earth element Holmium (Ho). Ho has a 128 dimensional ground state manifold, the largest of any stable atomic isotope. Experiments will demonstrate control of the quantum state within this manifold using tunable, single frequency lasers, and make basic spectroscopic measurements of several properties of Ho. These measurements are motivated by two high impact applications. The first is the possibility of using collective encoding in the internal hyperfine states of Ho to define a 60 qubit quantum register. Measurements will be performed to validate the feasibility of this idea which would have a large impact on the field of quantum computing. The second application is the possibility of achieving negative refractive index in a gas of Ho atoms at a wavelength shorter than 1 micron due to the presence of near degenerate electric dipole and magnetic dipole transitions. Spectroscopic measurements will be performed to validate the feasibility of achieving neagative refractive index in Ho. Achieving such short wavelength negative refractive index with low absorption losses would have a large impact for photonics applications including superlensing and optical cloaking.
The broader impacts of the project are twofold. First, this research is an important step towards realizing a scalable quantum processor that exceeds the capabilities of conventional classical computers. The availability of such a device has the potential for transforming the state of the art in areas which include numerical mathematics, information security, and simulation of quantum systems related to the development of new, technologically valuable materials. In addition the achievement of negative refractive index at short wavelengths could have a large impact for imaging and cloaking technologies that are important in many fields including engineering, and biological imaging. Second, the research program will contribute to the training of students for careers in science and engineering. Training will occur via direct participation in the University based research program. We will also inform the local community about the importance of atomic physics to information technology, and new developments in the area of photonics. Outreach to the public will be facilitated by public visiting days at the UW Madison Physics department, laboratory tours, and participation in local media programs.
In this project we have used laser beams and magnetic fields to cool and trap Holmium atoms. Laser cooling of atoms was first demonstrated in the 1980s and more than 20 different elements have been laser cooled. This is the first time Holmium atoms have been laser cooled. Holmium is of interest because it has the most complicated state structure (128 states) of any stable atom. We are working to use these 128 states to build a quantum computer which may revolutionize our ability to perform difficult calculations. In order to perform laser cooling of Holmium we had to first develop a new experimental apparatus. This included a source of Holmium atoms, laser systems with the correct wavelength to cool Holmium, a vacuum system, and a sensitive camera and computer control to observe the measure the cooled atoms. The laser system involved developing a tunable source. We showed that commercial laser diodes, such as those used in blu-ray disk players could be adapted for these experiments. As part of the project graduate and undergraduate students have been trained in modern techniques in atomic physics and quantum information science. This training is preparing them for high technology careers in academia, government and research and development.