Microwave Atom Chip Traps for Atom Interferometry

This interdisciplinary project will design, construct, and characterize atom interferometers based on ultracold trapped atoms on a microwave atom chip. Atom interferometers are the most sensitive force measuring devices ever constructed. Notably, they are particularly well suited for precision measurements and detection of electric and magnetic fields, gravity, and inertial forces, such as accelerations and rotations. Applications of atom interferometers include inertial navigation in a GPS-denied environment, remote sensing of underground and underwater structures, measuring atom-surface forces, and searching for deviations of the gravitational force from the inverse square law. While most atom interferometers operate with freely propagating atoms, one of the main scientific goals of this project is to develop and evaluate atom interferometers based on atoms trapped on an atom chip device, ideal for building a compact, fieldable sensor. Furthermore, the project will control these atoms using AC Zeeman potentials (based on rapidly oscillating magnetic fields) a novel and little explored quantum control mechanism for applying forces on atoms using microwave fields generated in the vicinity of an atom chip. Graduate and undergraduate student researchers will be trained in atom interferometry, ultracold atom technologies, microwave engineering, and micro-fabrication techniques, as well as in the broadly enabling sciences of atomic and optical physics. This interdisciplinary project is a collaborative effort between ultracold quantum physicists at William & Mary and microfabrication engineers at Virginia Commonwealth University. More specifically, this project will construct ultracold trapped atom interferometers that are based on microwave AC Zeeman traps and potentials generated by a microwave atom chip. The research uses an interdisciplinary approach that combines materials science advances, microfabrication, and microwave engineering to fundamentally enhance spin-specific quantum control of ultracold atoms for trapping and interferometry. A major objective of this project is the microfabrication of a microwave atom chip: The chip uses a novel thin substrate of aluminum nitride, which has a large dielectric constant and high thermal conductivity, for generating strong microwave near fields. Furthermore, AC Zeeman potentials offer a transformational mechanism for spin-specific manipulation of ultracold atoms, and a major thrust of the project is to implement and study atom chip-based microwave AC Zeeman traps and evaluate their suitability for spin-dependent atom interferometry. Notably, the project will study the stability of trapped atomic spin states, the smoothness of the trapping potential, the application of additional microwave and radio-frequency dressing fields for sculpting complex potentials, and the viability of more compact chip structures. Finally, the project will investigate the use of microwave lattices for enhanced trapping and interferometry. 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.