Sending out an SRF, Fermilab and Northwestern Partner for Applied Superconductivity Center

Northwestern University and the Department of Energy’s Fermi National Accelerator Laboratory (CSA CSM) have established a new research center where scientists will focus on advancing superconductivity, hoping to produce societal gains in the fields of particle physics, solid-state physics, materials science, medicine, energy and environmental sciences. Included are investigations into the upper limit of performance of superconductors for next-generation particle accelerators, the development of superconducting devices for quantum information science and technology and an expansion of superconducting materials research.

“Northwestern and Fermilab share a commitment to foundational discovery that can lead to transformative advances in many arenas,” says Jay Walsh, Northwestern VP for research. “By combining our efforts in this way, we create an ecosystem that provides the tools and collaborative environment to enable great scientists to pursue high-impact research. What is especially promising about this partnership is that each of our institutions brings unique strengths that allow us to meld theory and practice in exciting ways.”

Walsh’s colleagues at Fermilab agree, expressing enthusiasm about prospects for the new facility, called the Center for Applied Physics and Superconducting Technologies (CAPST). Anna Grassellino, CAPST co-director and a Fermilab physicist, is working to develop SRF cavities with improved performance at lower operational costs. Her research on nitrogen doping of niobium SRF cavities was a breakthrough discovery that led to a major improvement in the performance (quality factor) of SRF cavities. The Fermilab results have been adopted as the standard for SRF cavities for particle accelerators used in other research and industrial laboratories worldwide. The research is expected to enhance superconducting accelerators used for a broad spectrum of scientific machines, medical devices and nuclear energy applications.

“It is fascinating how particle accelerators can be very large and complex installations, but their ultimate performance depends strongly on the physics of superconducting materials at the nanometer scale,” Grassellino says. “At Fermilab, we have found that to push the boundaries of accelerator technology, we must confront the science and fundamental understanding of the physics in play in the superconducting materials used for cavities or for magnets. Fermilab knowledge and experience in the applied world, together with the knowledge and understanding of superconductivity from the Northwestern side, is a very powerful mix. And I can’t wait for this mix to guide us to the next breakthrough in accelerator technology.”

Members from each institution will meet in person at Fermilab and Northwestern about twice per month, and use SMART electronic whiteboards and video communication to share information more frequently. The team includes Northwestern faculty Venkat Chandrasekhar, William Halperin, John Ketterson, Jens Koch and Nate Stern, all experts in physics and astronomy, as well as David Seidman, materials science; and eight Fermilab staff members, including Grassellino and Alexander Romanenko, who hold adjunct appointments in physics and astronomy at the university.

The collaboration is already paying dividends, with Northwestern having been awarded a research grant for CAPST from the Physics Division of the National Science Foundation. “This new award will allow the CAPST research team to develop a detailed understanding for the physical processes that limit the accelerating field and quality factor of SRF cavities and with that knowledge to push the performance level toward theoretical limits,” says James Sauls, CAPST co-director and an expert in theoretical physics. “The grant from NSF will also help bring a greater presence of accelerator science to the university and provide new research opportunities for graduate students, both at Northwestern and Fermilab.”

A large variety of SRF cavities are used in particle accelerators. Fermilab produced its first high-energy particle beam on March 1, 1972. Since then hundreds of experiments have used Fermilab’s accelerators to study matter at ever-smaller length scales and investigate physical processes thought to take place in the early evolution of the universe.

In addition to SRF accelerators, CAPST will foster research and collaboration in the rapidly developing research field of quantum computing. Romanenko, for example, is leading the new SRF-based quantum computing architecture effort at Fermilab and a new subkelvin dilution refrigerator will be installed in the fall to begin experiments. And Koch, director of graduate studies in Northwestern’s Graduate Program in Applied Physics, is an expert in quantum electronics and superconducting quantum circuits (SQC).

Quantum computing based on SQCs takes advantage of the preservation of information provided by superconducting circuit elements. There are major efforts under way at universities, places like Google, Microsoft, IBM and Northrop-Grumman, and national laboratories to develop the next generation of computing machines based on quantum logic elements. CAPST will pursue superconducting based quantum circuits.

“Jens Koch is a leading expert in the theory of superconducting quantum circuits and has played an important role in discovering how to improve the performance of superconducting quantum bits (qubits), the basic element of a quantum computer,” Sauls says. “Fermilab and Northwestern already have basic research programs aimed at quantum computing. The combination of our efforts will allow us to pursue new directions with the goal of developing new types of qubits for next generation superconducting quantum devices.”