Obituary of Marc J. Feldman

Marc J. Feldman a Senior Scientist and Professor at the University of Rochester in Rochester, New York died on December 4, 2007 after a brief illness with lung cancer. Marc was a brilliant theoretical scientist and a creative experimentalist and throughout his career he applied his talent for bridging the gap between theory and experiments to the fields of superconductivity and superconducting electronics.

Marc was born on June 21, 1945 in Philadelphia and attended the University of Pennsylvania where he earned his B.A. and M.S. degrees in Physics in 1967. He won a NSF Graduate Fellowship and enrolled in the Ph.D. program at the University of California at Berkeley where he worked with Professors Raymond Chiao and Charles Townes completing his thesis on the Theory of the Unbiased Josephson Junction Parametric Amplifier in 1975. He remained at Berkeley as a post- doctoral researcher until 1978 when he accepted a position as a Visiting Scientist at Chalmers University in Gothenburg, Sweden. In 1981 Marc won a NRC Fellowship and moved to the NASA/Goddard Institute for Space Studies in New York where he remained until 1984 when he moved to the University of Virginia at Charlottesville. In 1989 Marc made his last professional move when he became a Scientist and Associate Professor of Electrical Engineering at the University of Rochester.

At Berkeley Marc wrote a paper entitled “An inverse AC Josephson effect voltage standard,” with Ray Chaio and Mogens Levinsen, who was visiting Berkeley from Denmark, which turned out to be one of Marc’s most cited papers. They showed that it was possible to have an unbiased Josephson junction with no DC current flowing through it, and yet, in the presence of strong microwave fields, be in a state of finite DC voltage which laid the foundation for the presently employed international voltage standard.

After moving to Chalmers Marc’s research focused on low noise Superconductor-Insulator-Superconductor mixers. His work led to design improvements that enabled practical devices now used in many radio observatories around the world and in space. During this time he also developed a liking for wearing Swedish clogs, which became a hallmark for many years.

From Chalmers University, Marc moved to the NASA/Goddard Institute for Space Studies at Columbia University. There, he continued his work on superconducting heterodyne receivers based on superconductor-insulator-superconductor (SIS) tunnel junctions and he was instrumental in developing early SIS receivers at 115 GHz for the Columbia/GISS Sky Survey Telescope and at 46 GHz for cosmic microwave background observations. While at GISS, he collaborated with John Tucker of the University of Illinois in writing what has become the standard reference for SIS receiver designers, Quantum Detection at Millimeter Wavelengths, now universally referred to as “Tucker&Feldman.”

In 1985, Marc moved with several of his GISS colleagues to the University of Virginia where they developed SIS tunnel junction receivers, which are still in use on the Kitt Peak 12-meter mm-wave telescope.

In 1989 Marc moved to the Electrical Engineering Department at the University of Rochester. Over the next several years Marc made many contributions to the emerging field of rapid single flux quantum digital electronics including understanding the noise and error rates in superconducting digital circuits and developing design principles for constructing robust digital circuits. Marc’s group also experimentally demonstrated RSFQ digital circuits composed of thousands of Josephson junctions operating at clock speeds in excess of 20 GHz an impressive speed at the time.

In 1996 Marc proposed that superconducting quantum computers built of Josephson junction qubits could be feasible and he worked on this topic for much of the following decade. A 1997 paper entitled “Prospects for quantum coherent computation using superconducting electronics” written with Mark Bocko and Andrea Herr, presented conceptual designs for Josephson flux qubits and proposed methods for manipulating and sensing such superconducting qubits.

Recently Marc turned his attention to room temperature ballistic electronics and led a team that envisioned room temperature transistors employing electrostatic control of electrons in a 2D electron gas. His group recently demonstrated transistor action in such devices when his illness was discovered in late 2007.

Marc balanced his scientific life by being a devoted husband to his wife Susan and father to his sons Lucas and Benjamin. One of Marc’s passions was his sons soccer playing and he enthusiastically participated as both a coach and as their biggest fan, animatedly following the action up and down the sidelines. Marc also is survived by his brother Richard and sister Barbara.