2024 Investiture Information

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Jones Seminar: Microwave Quantum Circuits Using Epitaxial Al-InAs Planar Josephson Junctions



3:30pm - 4:30pm ET

Spanos Auditorium, Cummings Hall

Optional ZOOM LINK
Meeting ID: 924 1038 8333
Passcode: 827237

Epitaxial superconductor and semiconductors Josephson junction can enable a superconducting qubit architecture with full electric field control. The current flow is facilitated by Andreev bound states in the semiconductor weak-link. By biasing with an applied gate voltage one can tune the Fermi level in the semiconductor and the occupation of Andreev bound states, effectively controlling the conduction through the junction. It was shown that InAs makes an excellent candidate for a proximitized semiconductor because it makes an ohmic contact with superconducting metals such as Al.

We discuss epitaxial growth of Al on InAs and nanofabrication of these materials into voltage-tunable quantum devices such as Gatemons and qubit couplers. We also study the presence of unpaired quasiparticles (QPs) in the superconductor, usually referred to as quasiparticle poisoning. Understanding the nature of QPs is a necessary task before constructing advanced quantum information processing devices. Using locally injected and thermal quasiparticles, we study QP loss and QP poisoning in our Al-InAs Josephson junctions incorporated in a superconducting quantum interference device (SQUID). Our measurements suggest that electron-phonon interactions play a significant role in the relaxation mechanisms of our system, while electron-photon interactions and electron-phonon interactions govern the clearing mechanisms.

Hosted by Professor Mattias Fitzpatrick.

About the Speaker(s)

Javad Shabani
Associate Professor of Physics, NYU

Javad Shabani

Javad Shabani is an associate professor of physics at New York University, director of the Center of Quantum Information Physics, and is an expert in quantum materials and devices for computation technologies. He received his PhD from Princeton in 2011. After two years of research on semiconductor-based qubits at Harvard, he joined UC Santa Barbara. There, he worked closely with Microsoft research on hybrid semiconductors/superconductors heterostructures to study topological superconductivity. His current research interests are: 1) Novel states of matter at interfaces with focus on hybrid superconductor-semiconductor systems; 2) Mesoscopic and nanoscale physics with emphasis on low dimensional semiconductors with focus on new materials/device development for quantum information; 3) Physics of integer and fractional quantum Hall effect; and 4) Epitaxial growth of compound superconducting metals-semiconductor, including high mobility two-dimensional electron systems and nano-plates using molecular beam epitaxy.


For more information, contact Amos Johnson at amos.l.johnson@dartmouth.edu.