Marvin Denham Girardeau, a research professor of optical sciences at the University of Arizona, died on 13 January 2015 at his home in Green Valley, Arizona. He was a mathematical physicist with an unusual nonlinear career that culminated in his remarkable impact on ultracold atom physics.
Marvin is best known for introducing in 1960 an exactly solvable model describing hard-core bosons in one dimension that effectively mimic polarized fermions. That and subsequent work influenced the foundations of quantum mechanics and many-body theory, as his contributions clearly showed that quantum exchange statistics in one dimension is ill-defined as an isolated concept and inextricably linked with interparticle interactions. Although that model, known as Tonks–Girardeau gas after Marvin and Lewi Tonks, ignited an avalanche of studies of “beautiful,” solvable many-body models, it did not find its way into the laboratory until almost a half century later.
Born on 3 October 1930 in Lakewood, Ohio, Marvin exhibited a creative mind early on. As a teenager, he was an avid chemistry experimenter and, among other things, succeeded in synthesizing nitroglycerine. He received a BS from Case Institute of Technology in 1952 and an MS from the University of Illinois at Urbana-Champaign in 1954. After earning his PhD in 1958 at Syracuse University, under the guidance of Richard Arnowitt, Marvin was invited by J. Robert Oppenheimer to the Institute for Advanced Study.
Marvin worked at Brandeis University with Eugene Gross in 1959–60, at Boeing Scientific Research Laboratories in 1960–61, and at the University of Chicago with Gregor Wentzel in 1961–63. He then became an assistant professor at the University of Oregon; in 1967 he was promoted to full professor. He became emeritus in 1995. In 2000 Marvin began working as a research professor at the University of Arizona. Over the course of his academic career, he took sabbatical leaves to the Universities of Brussels, Toulouse, and Nice, not only for pure science but for his linguistic and historic interest in French: The surname Girardeau came from Huguenot French ancestors. In addition, he received a 1984 Humboldt Prize.
Marvin’s career is unusual in that it received a major boost during his emeritus appointment. A decisive factor was the experimental realization of Bose–Einstein condensation of ultracold alkaline atoms in 1995 by Eric Cornell and Carl Wieman at JILA and by Wolfgang Ketterle at MIT soon afterward. Three years later one of us (Olshanii) demonstrated that the scattering of atoms in tight waveguides has a resonant behavior. That system thus realized the Lieb–Liniger model, whose solution was discovered in 1963, which consists of one-dimensional bosons with finite-strength contact interactions. At the resonance, when interaction strength between atoms becomes infinite, the Tonks–Girardeau regime is reached. That insight paved the way for experimental realizations of the Tonks– Girardeau gas and the super Tonks– Girardeau gas, a related model with even stronger quantum correlations.
Several laboratories around the world soon confirmed those realizations. As a result, the Tonks–Girardeau regime became a paradigmatic reference system for understanding low-dimensional, strongly correlated quantum fluids. Less predictably, it turned out to be an ideal test bench for developing our understanding of isolated quantum systems, their thermalization dynamics, and, ultimately, the foundations of statistical mechanics. Among Marvin’s other contributions, which inspired many colleagues, were the Girardeau–Arnowitt theory of the many-body problem of liquid helium, developed with Arnowitt in the late 1950s; the fermionic Tonks–Girardeau gas, with the wavefunction obtained by Girardeau mapping from an ideal Bose gas; and Girardeau’s isomorphism, a map between the free-space sign representations of a reflection group and eigenstates of a quantum billiard whose walls are represented by the mirrors of the group.
In the wake of the one-dimensional experimental revolution, Marvin’s productivity grew considerably. Indeed, he introduced a plethora of exactly solvable models that exploited and extended his early insights dating back to 1960. His solid reputation was accompanied by memorable and endearing gestures of enthusiasm, and even in his late seventies he would not hesitate to take part in late-night poster sessions at conferences. Although he officially retired in 2010, he remained involved in research until his death.
Marvin was always conscious of the relevance his work on strongly correlated gases had to national defense. During the emeritus stage of his career, he led an Office of Naval Research project from 1998 to 2008 and an Army Research Office project from 2009 to 2012.
Those who had the pleasure of meeting Marvin might have been struck by his exceptional energy and passion; admirably, he preserved the curiosity of a 12-year-old throughout his career. His interests extended beyond the realm of physics. For decades he was an enthusiastic marathon runner. He experimented with wine making and grape growing, and he also enjoyed astronomy, hiking, and choir singing.
Observers have noted that when averaged over 50 years, the movies of Federico Fellini, the surreal filmmaker who knew no boundaries, are watched as often as the most successful blockbusters. The same applies to Marvin’s work on one-dimensional gases. And his career offers a lesson for incoming generations: Follow your heart; no matter how naive it may seem in the beginning, it will pay off at the end.
