Dramatic progress has been made in the last decade and a half towards realizing solid-state systems for quantum information processing with superconducting quantum circuits. Artificial atoms (or qubits) based on Josephson junctions have improved their coherence times more than a million-fold, have been entangled, and used to perform simple quantum algorithms. The next challenge for the field is demonstrating quantum error correction that actually improves the lifetimes, a necessary step for building more complex systems.
Here we demonstrate a fully operational quantum error correction system, based on a logical encoding comprised of superpositions of cat states in a superconducting cavity. This system uses real-time classical feedback to encode, track the naturally occurring errors, decode, and correct, all without the need for post-selection. Using this approach we reach, for the first time, the break-even point for QEC and preserve quantum information through active means.
Moreover, the performance of the system matches with predictions, and can be dramatically improved by making the protocol more fault tolerant. Mastering the practice of error correction, and understanding the overhead and complexity required, are the main scientific challenges remaining for reaching scalable quantum computation with this technology.
Robert Schoelkopf is the Sterling Professor of Applied Physics and Physics at Yale University. His research focuses on the development of superconducting devices for quantum information processing, which will lead to revolutionary advances in computing.
His group is a leader in the development of solid-state quantum bits (qubits) for quantum computing, and the advancement of their performance to practical levels. Together with his collaborators at Yale, Professors Michel Devoret and Steve Girvin, their team created the new field of "circuit quantum electrodynamics," which allows quantum information to be distributed by microwave signals on wires. His lab has produced many firsts in the field based on these ideas, including the development of a "quantum bus" for information, and the first demonstrations of quantum algorithms and quantum error correction with integrated circuits.
A graduate of Princeton University, Schoelkopf earned his Ph.D. at the California Institute of Technology. From 1986 to 1988 he was an electrical/cryogenic engineer in the Laboratory for High-Energy Astrophysics at NASA's Goddard Space Flight Center, where he developed low-temperature radiation detectors and cryogenic instrumentation for future space missions.
Schoelkopf, who came to Yale as a postdoctoral researcher in 1995, joined the faculty in 1998, becoming a full professor in 2003. He is also the Director of the Yale Quantum Institute.
Professor Schoelkopf has been recognized as a fellow of both the American Association for the Advancement of Science and the American Physical Society. In 2009, he was awarded the Joseph F. Keithley Award of the American Physical Society for the development of high-frequency measurement techniques to probe quantum devices and nanostructures, and in 2013 he shared, with his colleague Michel Devoret, the John Stewart Bell Prize for fundamental and pioneering experimental advances in superconducting qubits. In 2014 he received, the Max Planck Forschungspreis, and together with Devoret and John Martinis (UCSB), the Fritz London Memorial Prize for Low Temperature Physics. In 2015, Professor Schoelkopf was elected to the National Academy of Science.
In 2015 Schoelkopf co-founded (together with Michel Devoret and Luigi Frunzio) Quantum Circuits, Inc., (or QCI, www.quantumcircuits.com), a private venture aimed at developing scalable quantum computers based on superconducting circuits. In the near term, QCI is developing, industrializing, and selling components and devices that help enable the scaling of solid-state quantum computing.