Spectroscopy and Quantum-State Manipulation of Excited Rb Atoms and Molecules Using Optical Lattices

Regents Of The University Of Michigan - Ann Arbor, Ann Arbor MI

Investigators

Abstract

General audience abstract: Atomic spectroscopy is important in metrology, such as time measurement, and in efforts to learn about the fundamental workings of atoms and molecules. For instance, the 5S-5P-5D transition of the rubidium atom is used in practical vapor-cell atomic clocks, and its wavelength is used by the Consultative Committee for Length (CCL) as one of its references for realizing the meter. In the project, properties of the quantum states of the rubidium atoms are measured that can affect the accuracy of such devices. The laser-spectroscopic investigations conducted in the project also aim at a better understanding of highly excited atoms (Rydberg atoms) in laser atom traps, at the exploration of a new type of molecule that involves Rydberg atoms, and at high-precision measurements of Rydberg-atom transitions that can help address current questions in fundamental physics (including, for instance, what is the exact size of building blocks of matter such as the proton). Rydberg atoms are a critical component in numerous quantum devices that are being worked on in science and technology, making a thorough understanding of their physics and of the breadth of their possible applications an important goal. The research engages graduate students in the fields of laser physics, optics, quantum mechanics and quantum measurement technologies, which are areas that are highly sought-after in academia, industry and government. Technical audience abstract: The project work includes an investigation of the AC polarizability and the photo-ionization cross section of the rubidium 5D3/2 level in a strong 1064-nm laser field. Lasers are stabilized and scanned over several GHz, while being referenced to lasers locked on atomic vapor cells. AC shifts and photo-ionization-induced line broadening of the Rb 5D3/2 level in the 1064-nm laser field are on the same order of magnitude, allowing a measurement of both quantities. In the same setup, laser-spectroscopic studies are conducted to explore the physics of Rydberg atoms in molecules and in optical lattices. Rydberg levels can become heavily mixed in GHz-deep lattices, leading to novel types of potential energy curves, which are measured. The project also aims at research on a new type of molecule between a Rydberg atom and a positive ion. In related work, high-precision Rydberg-level spectroscopy is conducted using an optical-lattice modulation technique, a novel sub-Doppler spectroscopic approach to Rydberg-atom spectroscopy that is based upon the ponderomotive interaction of bound electrons with fields rather than the more common electric-dipole interaction. All-optical preparation of circular Rydberg atoms, which allow for the most precise of Rydberg-atom-based spectroscopies, using a time-orbiting optical lattice is pursued. The work is conducted by a principal investigator and several graduate students, and it will offer opportunities for undergraduate students. 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.