The field of atom optics utilizes the fact that atoms propagate as waves. The phase and amplitude of atom waves will be studied with an atom interferometer in order to precisely measure several atomic properties. The atom wave phase shift due to nearby surfaces will be measured to determine atom-surface van der Waals interaction strengths. The atomic response to an electric field will be observed in order to report the atomic polarizability of several different atoms. Both of these experiments use a separated-path Mach-Zehnder atom interferometer that is built with nano-structured gratings. Because the nano-gratings serve as beam splitters for different types of atoms, they allow us to compare the properties of several different atoms. Further characterization of the nanostructures themselves will be accomplished with a new type of electron interferometer that also uses nanofabricated gratings as beam splitters. The use of nano-gratings for both electron and atom interferometry expands the frontiers of quantum physics in several directions. Measurements of van der Waals interaction strengths will test theoretical models that use quantum electrodynamics to predict the potential energy for atoms located 1 to 50 nanometers from multi-layered surfaces. Measurements of atom wave dynamics near surfaces will also help us design compact atom-chip interferometers that may soon become state-of-the art geophysical sensors such as gyroscopes. High precision atomic polarizability measurements serve as a benchmark to test models of atomic structure that are also needed to interpret atomic parity violation experiments as a test of the standard model in particle physics. Thus, experiments with nano-gratings will extend applications of matter-wave interferometry in order to test basic theories in quantum electrodynamics, physical chemistry, and fundamental physics. This work advances the science of Atom Optics and pioneers new applications for nanotechnology. The broader impact of this work also includes both graduate and undergraduate training in atomic, molecular, and optical physics research.
We developed several new applications in the field of atom optics. Each of these applications uses 100-nanometer period material gratings that we call nanogratings. We use nanogratings to diffract and interfere beams of atoms. Observing the wave property of atoms in this way enables several new types of highly precise measurements of atomic properties. These findings are described in more detail at our web site www.atomwave.org. We used an atom interferometer, in which nanogratings serve as beam splitters for atoms, to measure the electric polarizability of Na, K, and Rb atoms with unprecedented precision. We made measurements by studying how electric fields cause phase shifts for the atom waves. Our measurements of polarizability ratios have a precision of 0.3%, and this serves as an excellent test of theoretical atomic structure calculations. We also used diffraction from a nanograting to measure atomic energy-shifts when a surface is 10 nanometers away. This is a van der Waals interaction. Our measurements for different atoms (Li, Na, K, and Rb) interacting with the same (silicon nitride) surface are as precise as 2%. Using this approach we detected the contribution of atomic core electrons (not just the outer most valance electron) to the van der Waals atom-surface potential. We demonstrated that the type of surface does not strongly affect the ratios of van der Waals potential energy for different atoms. Because of this, our measurements are more sensitive to atomic core electrons. In another laboratory we demonstrated two new types of electron beam interferometers. We built the first Lau interferometer for electrons using nanogratings as beam splitters. With this apparatus we demonstrated electron holography. We also built the first Talbot interferometer for electrons. Thus we proved that fabricated nanogratings can serve as a new type of beam splitter for coherent electron optics experiments. Intellectual merit: We made precision measurements of atomic polarizability for Na, K, and Rb atoms. We made precision measurements of atom-surface van der Waals potential coefficients (C3) for Li, Na, K, and Rb atoms. These precision measurements test theoretical atomic structure calculations. We also demonstrated that nanogratings work for electron interferometry. Broader Impact: Four PhD students and ten undergraduate students were trained in atomic physics research methods as a result of this project. We are finding new applications for nanotechnology.
