Obituary of Yehoshua Levinson

Yehoshua Levinson, Professor of Physics at the Weizmann Institute, Israel, passed away on July 28 2008, after a long illness. He joined the Weizmann Institute in 1992 following a distinguished career in the Soviet Union. He was an expert in, and made lasting contributions to a range of problems in theoretical atomic, solid‑state and non‑equilibrium physics, while closely interacting with fellow experimentalists and inspiring students and young colleagues. He never boasted of his outstanding technical abilities, but rather emphasized the basic physical understanding. His approach to Physics was insightful and creative. He will also be remembered as a generous person of exceptional integrity and love for physics.

Yehoshua began his education in Physics as a student at the very prestigious Moscow Engineering Physics Institute (MIFI). Soon thereafter, the unprecedented anti Semitic campaign instigated by the Soviet regime led to his expulsion from that institution. Yehoshua was forced to return to Lithuania. While serving in the military he started pursuing his research in atomic physics, where he made important contributions to Racah algebra and the Wigner 6j‑symbols, mostly by developing a diagrammatic technique (still viable today) for the computation thereof. His results have been cited in the iconic text‑book of Landau and Lifshitz, and have been published as a book, Mathematical Apparatus of the Theory of Angular Momentum.

In the early 1960’s Levinson has shifted his interests to the field of condensed matter theory, where he was mostly interested in transport and relaxation of electrons in semiconductors. Yehoshua has become a leading expert in kinetics and non‑equilibrium processes. The pinnacle of his work during that time was the theory of electron flowing in crossed strong electric and magnetic fields. He has shown that under those conditions the energy distribution function of hot electrons is inverted, rendering it exploitable for the design of IR semiconductor lasers.

When the prestigious Landau Institute was created, Yehoshua was among the few selected and invited to join the Institute. This second stage of his career was taken both as a token of recognition and a challenge. Yehoshua worked at the Landau Institute from 1968 till 1985. Then, till his immigration to Israel, he became the head of the Theory Department of the Institute of Microelectronics Technology. Looking back at a number of milestone papers he has co‑written during those years in Chernogolovka with his then Ph.D. students (Kazakovtsev, Maslov, Esipov, and Sukhorukov to name a few of his 14 students), covering disparate topics such as hot phonons, hot electrons, the physics of quantum point contacts and more, he could certainly be regarded as one of the pioneers of Mesoscopics.

During that period his long‑term friendship and collaboration with Prof. V. Gantmakher has flourished, leading to a prime example of a fruitful interaction between Yehoshua (a theorist) and an experimentalist (one of Levinson’s outstanding traits). This has culminated in one of the most original books in solid state physics (Carrier scattering in metals and semiconductors, Elsevier, Amsterdam, 1987).

In 1992 Levinson began his new life in Israel. His presence in the new scientific environment was soon felt: in addition to his own research, his door was always open for advice and discussions with senior colleagues and students alike. His originality, professionalism, and outstanding human attributes were appreciated by everybody around him.

Yeoshua had an exceptional ability to communicate with experimentalists. His broad knowledge of experimental techniques and his open mind made him the prime target for experimentalists to examine puzzling results and discuss possible interpretations. These sessions were the beginning of a process through which insight and clarity were often resulting in joint papers. Examples range from a detailed understanding of dissipation in ballistic devices, the removal of the mystery behind controlled dephasing ( which path experiments) leading to an influential paper, interpretation of various mesoscopic shot noise experiments, and the analysis of the roles of electron mobility and complex disorder in the physics of quantum Hall effect.

For his work Prof. Levinson has been awarded several prizes, including the USSR State Prize in Science and Technology (1987) and the Alexander von Humboldt Award (1996).

Professor Levinson has been arguably the most successful example of absorption among the senior physicists that immigrated to Israel in the wake of the collapse of the Soviet Union. Everyone benefited from his presence, and, very fortunately, he too enjoyed his new home. Yehoshua was dedicated to his work up to the last moment. He fought his illness with braveness and perseverance and passed away with dignity, just as he lived.