Posted in: Quantum Computing

Testing Next-Gen Qubits

qubit

This 16 qubit processor is available for use by developers, researchers and programmers to explore quantum computing using the IBM Q Experience.

The qubit, that fundamental element of information processing on a quantum computer, is getting a research boost from the National Science Foundation’s Research Advanced by Interdisciplinary Science and Engineering (RAISE): Transformational Advances in Quantum Systems (TAQS) grant for “materials spectroscopy for next generation superconducting qubits,” one of 25 grants awarded under this effort. The goal of the five-year agreement, as the name implies, is to improve superconducting qubit performance through a deeper understanding of physics and chemistry of surfaces and interfaces – what qubits are fabricated on, and controlled by. For our part, the IBM Q team will characterize quantum architectures based on various surface treatments and new materials synthesized by Princeton University and the University of Wisconsin, as well as bring on a half-dozen or so undergraduate interns in the summer of 2019.

This academic-industry collaborative research effort between Princeton University, the University of Wisconsin at Madison and IBM will bring together advanced methods in materials science, physics and electrical engineering to solve long-standing, fundamental materials problems in superconducting (SC) qubit devices. Although SC qubits are leading candidates to be the building blocks of next generation quantum computers, their coherence times – how long they’re available to compute – are currently insufficient for practical, everyday computing, due to noise sources, including, in-part, the materials they’re made of.

In this grant, we propose using complementary surface spectroscopy tools to determine the chemical and physical nature of defects in differently prepared SC devices. We’ll then correlate those measurements with qubit performance to discover what types of defects are the most deleterious. Then, new surface treatments and fabrication techniques will be tested that are specifically aimed at removing those defects, and new prototype qubits will be created that make use of treatments that are predicted to be beneficial.

qubit

STM measurements of defects and impurities in NbOx layers. (Far left) Electron hopping processes in thin oxides that could lead to TLS noise in SC qubits. (bottom) Spectroscopic signatures of noise generating processes in NbOx oxides. (bot. left) Electron resonances due to localized defect wavefunctions coupled with metal. (bot. mid) Spatial variations of SC gap due to NbOx inhomogeneity. (bot. right) Mid-gap states formed by defects in oxide coupled to the SC metal.

In order to remove obstinate defects that are deemed intrinsic to currently used materials, substrate alternatives to silicon, for example, will be explored that are chemically inert, display low microwave loss, and can be grown at ultrahigh purity. We envision a virtuous cycle in which knowledge gained from fundamental materials spectroscopy is rapidly translated into advances in qubit device fabrication, which provides feedback to identify entirely new materials systems and new qubit designs, using theoretical support to develop new methods for benchmarking qubits.

Developing next-gen quantum talent

The NSF also made an educational program central to the grant. It includes a joint 2019 summer internship and NSF Research Experiences for Undergraduates (REU) at both universities and IBM Research’s IBM Q lab in New York. There is significant demand for quantum computing skills. This first-of-a-kind program to combine industry and academic REU program will integrate in-lab research, teaching, and lectures. It’s a unique opportunity that will give younger students the opportunity to perform state-of-the-art research in quantum science, materials engineering, and condensed matter physics at an academic lab, combined with frontier industry research in quantum engineering and quantum information science here at IBM.

Watch this blog for updates on when REU applications open next year. If you want to explore quantum computing now, visit the IBM Q Experience and run experiments on real 5-qubit and 16-qubit systems, as well as simulators.

qubit

Pat Gumann

IBM Q