Rudolf Morf, a significant condensed-matter theorist, passed away on September 14, 2020, near Zurich, Switzerland.
Rudolf made very influential contributions to theoretical studies of the melting of electron crystals, fluid dynamics, fractional quantum Hall physics, and optics. He made important efforts to improve the efficiency of photovoltaic devices.
He was the first head of the condensed matter theory group newly created at the Paul Scherrer Institute in 1998. He lead this group with much wisdom for more than ten years, until his retirement in 2008.
Born on June 16, 1943, in Winterthur, Switzerland, Rudolf's first few years were spent in the ancestral family home in Kyburg, a small village near Zurich. He much cherished the place. He had fond memories of the primary school, where a single teacher was in charge of teaching all the children from Kyburg.
His father becoming an accomplished chemist working for the chemical company Sandoz, the center of gravity of the Morf family was moved to Basel. Rudolf learned Greek and Latin in the Basel high-school before beginning to study physics at the University of Basel. In 1972, he earned his PhD with a thesis on "Coulomb excitation effects in neutron transfer reactions", a subject belonging to the field of theoretical nuclear physics. His advisor was Professor Kurt Alder.
A few years later, Rudolf's interests had shifted to the theory of critical phenomena. He turned down a staff position at IBM Research, Zurich, in favor of a postdoctoral position at Harvard University, where he spent the years from 1977 until 1980. He collaborated with Bertrand I. Halperin, Daniel S. Fisher and Uriel Frisch. Rudolf's interests became broad, ranging from the melting of a two-dimensional electron crystal to complex flows of classical fluids.
Upon returning to Switzerland, Rudolf joined the RCA Laboratories in Zurich, which got integrated into the Paul Scherrer Institute in 1987. He embarked on numerical studies of trial wave functions for low-density electron gases exhibiting the fractional quantum Hall effect 1. These systems were the first examples of states of matter exhibiting a certain type of topological order. His studies of the quantum Hall states at filling fraction 5/2 became very influential. They provided convincing theoretical arguments for the existence of gapped phases of matter exhibiting quasi-particles known under the name of non-Abelian anyons. The braiding of non-Abelian anyons opens a promising way towards realizing certain quantum computations.
Another passion of Rudolf's was to advance the efficiency of solar-energy panels. He strongly believed in the future importance of solar and other forms of renewable energy. Thus, besides his studies at the forefront of theoretical condensed matter physics, Rudolf also contributed many results to applied optics, optimized gratings for photovoltaic devices, the microscopic theory of quantum-well solar cells operating out of equilibrium, etc.
Rudolf's inexhaustible energy, enthusiasm, and optimism were most inspiring for all the members of the group he lead at PSI. He nurtured a scientific environment that greatly promoted the creativity of the members of his group. He would delight his colleagues with chocolate truffles each time he had missed the right train stop, lost as he was in his thoughts about physics. After his retirement, he continued to show a keen interest in physics questions, and he remained in close contact with colleagues and students.
Rudolf loved horses. He found inspiration for his work during excursions on horseback. His horses taught him patience.
His outstanding human qualities became apparent when he mediated disputes in Kyburg arising, for example, from the ringing of church bells before sunrise.
Rudolf shared his love of classical music with his family, friends and colleagues by organizing most memorable concerts at his home. He started to play the piano again during his retirement. His ambition was to play all pieces of the "Well-Tempered Clavier" by Bach, who was his favorite composer. He would practice daily and often for several hours.
Rudolf's extraordinary generosity showed in many ways, not least in him accepting and supporting other people's way of life. We will miss Rudolf dearly.
Christopher Mudry, Markus Müller, Dionys Baeriswyl, Jürg Fröhlich
1 Rudolf Morf contributed to our series "Milestones in Physics" with an article in the SPG Mitteilungen Nr. 43.
[Published: May 2021]