RAISE: TAQS: Materials spectroscopy for next generation superconducting qubits

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Nontechnical description: Quantum computers can perform calculations that are beyond the capabilities of current classical computers and, if successfully developed, would revolutionize many aspects of science, technology, and commerce. The performance of present-day, small quantum computers is limited by interference from background noise that prevents useful computations from being done. This noise can arise from imperfections in the materials used in the prototypes - materials selected for other favorable properties - and the goal of this project is to discover which materials cause the noise, and how to improve or replace them. In doing so, this research could not only impact quantum computers; the development of low noise materials could also be useful in creating better sensors and more sensitive signal amplifiers. This project also serves to train a new generation of scientists who are conversant across several fields, including quantum information science, experimental condensed matter physics, materials growth, and device engineering. This project includes a program to help students perform research at both academic and industry labs, specifically at the IBM Quantum Computing group in Yorktown Heights, NY. This training is necessary for the development of a workforce that can spearhead future quantum information science and quantum engineering.Technical description: This collaborative, interdisciplinary research effort between academia and industry brings together advanced methods in materials science, physics and electrical engineering to solve long-standing, fundamental problems in superconducting (SC) qubit devices. Although SC qubits are one of the leading candidates for quantum computing, their coherence times are currently insufficient for most applications. Despite significant progress in extending qubit coherence over the last 20 years, the microscopic sources of loss and noise remain generally unknown. This project utilizes direct material and surface spectroscopy tools to determine the chemical and physical nature of defects in state-of-the-art SC qubit devices, and correlates that characterization with qubit performance to discover the defects that are the sources of the decoherence. Using this information, the research team devises new surface treatments and fabrication techniques aimed at removing those defects, and those techniques are employed to fabricate and measure new prototype qubits. Building on this knowledge, the research team also explores alternative materials systems that are chemically inert, display low microwave loss, and can be grown with ultrahigh purity as substrates for qubits. This research effort is structured as a virtuous cycle in which knowledge gained from fundamental materials spectroscopy is rapidly translated into advances in qubit device fabrication, providing feedback to identify entirely new materials systems and new qubit designs, using theoretical support to develop new methods for benchmarking qubit performance.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.