Gennady Petrovich Berman

Gennady Petrovich Berman was born in Kiev on 19 October 1946 and died on 5 March 2022 in Los Alamos, New Mexico.

“Gena,” as he was widely known to his many friends and colleagues, earned a BS in physics at Novosibirsk State University in 1970, a PhD in physics at the Kirensky Institute of Physics in 1974, and a Second Doctor Degree in physics and mathematics at the Institute of General Physics in Moscow in 1989. For 20 years he was a professor at the Institute of Physics of the Siberian Branch of the Russian Academy of Sciences in Krasnoyarsk. During this period, he became one of the leading figures in the remarkable cadre of Russian (then Soviet) scientists working on intrinsically nonlinear problems and, in particular, “chaos.”

As a result, Gena was invited to the first joint American-Soviet Union gathering of nonlinear scientists, sponsored jointly by the American Institute of Physics and the Soviet Copyright Agency VAPP, that was held at Woods Hole, Massachusetts, in the summer of 1989. There he met one of us—DC, then director of the Center for Nonlinear Studies (CNLS) at Los Alamos National Laboratory—and, as a result of the strong overlap of interests, Gena was invited to visit the CNLS. Beginning in 1991, he became a scientific collaborator at the center. Gena moved to the US in 1992, and from 1993 until his retirement in 2014, he was a staff member in the Theoretical Division of Los Alamos, initially in the CNLS and later in the Complex Systems Group, where he served as a deputy group leader. After his retirement he continued working at Los Alamos as a guest scientist.

Gena’s first internationally acclaimed contribution to physics was his study, together with George Zaslavsky, of the conditions (and time scales) for the validity of the semiclassical approximation to quantum systems that are chaotic in the classical limit. This quantum generalization of the “Chirikov overlap criterion” was one of the pioneering results in quantum chaos. Importantly, over the following years, Gena demonstrated that this seemingly arcane concept of “quantum nonlinear resonance” plays a significant role in nonlinear quantum systems (i.e., any quantum system except the harmonic oscillator) and has important applications to problems of quantum nonintegrable systems and nanotechnology, including experiments in highly excited (Rydberg) atoms and in mesoscopic solid-state devices, including semiconductor superlattices.

During his years at Los Alamos, Gena produced several important results in quantum computation, both theoretical concepts and experimental implementations. He showed that the stability of an ion in a linear ion trap can be understood and controlled using the characteristics of effective quantum nonlinear resonances. This result had significant implications for one of the experimental systems currently being considered for quantum computation. Further, he modeled quantum computers with large numbers of qubits on a “normal” computer and obtained some important benchmarks to guide future studies aimed at realizing and improving quantum algorithms. He also explored a proposed solid-state realization of a quantum computer and established some of the necessary “figures of merit” that any device of this kind would have to meet to achieve reliable quantum computation.

Gena was an author of approximately 300 published papers and eight books in areas ranging across quantum chaos and stochasticity in nonlinear systems, photosynthetic and light-harvesting complexes, dynamics of electron transfer processes, atmospheric turbulence, quantitative finance, quantum computation, quantum annealing, decoherence, magnetic resonance force microscopy and single-spin measurements, Bose–Einstein condensation, and the Fermi-Pasta-Ulam-Tsingou problem.

Gennady Berman was an enthusiastic, dedicated, and valued colleague who collaborated fruitfully with a remarkable number of scientists from different fields, backgrounds, and countries. He was very patient and generous in sharing his deep understanding of physics and science in general with his younger colleagues. He remained actively and enthusiastically engaged in research during a long final illness, and his last paper, on magnetic resonance force microscopy, was published just weeks before his death. He will be greatly missed by his wife, Tamara, his son Dimitri and family, and his many colleagues and friends.