The University of Massachusetts Amherst
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Seminar: Karl Berggren

“Hacking the Superconducting Thin-Film: Electronics and Single-Photon Detectors”


Monday, October 5, 2015 - 4:00pm


Karl Berggren, Professor, Massachusetts Institute of Technology


Marston 132


In this talk, I will review superconducting nanowire single-photon-detector research, and discuss a class of brand-new superconducting electronic devices, also based on nanopatterned superconducting thin films.

Ultrasensitive photodetectors enable applications as disparate as deep-space communication, astronomical observations, quantum cryptography, and integrated-circuit evaluation. Often, superconducting detectors are used in situations where exceptional detector performance is required. With superconducting nanowires, single-photon count rates of 100s of mega-counts per second, system detection efficiencies above 90%, and timing uncertainty of less than 30 picoseconds have been realized. But existing detector technologies suffer from materials and design challenges that limit the ultimate performance of such systems.  To overcome these challenges, we are working on developing better pictures of how nanowires interact with currents, magnetic fields, heat flow, and optical absorption. In this seminar, I will describe the key physical questions and challenges we have faced, and present some of the devices that can be developed with this new understanding. 

I will also describe a new type of superconducting electronic device that uses only nanowires, and does not involve Josephson junctions. This device can be used to perform digital computation with superconductors. This new device is a variant of the superconducting cryotron, a technology developed by MIT professor Dudley Buck in the late 1950s as an integrated circuit even before transistors had been integrated. We call this device the nanoCryotron, or nTron.

Prof. Berggren is Professor of Electrical Engineering at Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, where he heads the Quantum Nanostructures and Nanofabrication Group. He is also Director of the Nanostructures Laboratory in the Research Laboratory of Electronics and is a core faculty member in the Microsystems Technology Laboratory (MTL). His current research focuses on methods of nanofabrication, especially applied to superconductive quantum circuits, photodetectors, high-speed superconductive electronics, and energy systems.  Prof. Berggren is a senior member of IEEE and a fellow of the International Society for Nanomanufacturing. He serves on the editorial board of the IOP Nanotechnology journal and was program chair of the 2014 Electron, Ion, Photon Beams and Nanofabrication Conference. From 2008 to 2014 he was an elected member of the board of the Applied Superconductivity Conference.