Laudatio

For his many original and outstanding contributions to quantum chaos
and mesoscopic systems

Prof. Dr. Steven L. Tomsovic

has been awarded the Martin-Gutzwiller-Fellowship 2006/2007
of the Max Planck Institute for the Physics of Complex Systems.

Steven L. Tomsovic is one of the world's leading researchers on quantum chaos and mesoscopic systems. His path to these fields started from nuclear physics, just as did Oriol Bohigas with whom (and Denis Ulmo) he wrote a review in Physics Reports that has become a standard for the literature. His formative thesis work with Bruce French in Rochester (USA) concerned various concepts of the nucleon-nucleon interaction. Then his career moved him to Orsay (France) and back in the USA, Harvard and the University of Washington.
From his large body of work, one can emphasize three main achievements. His participa-tion in the discovery of chaos-assisted tunneling stimulated further theoretical investiga-tions and experiments in microwave cavities, optical lasing cavities and, recently, in cold-atom optics experiments. His general exploration of quantum systems with a classically mixed phase space, separating regular and chaotic states, related classical transport flux to quantum matrix elements and demonstrated a new kind of localization in phase space.
He developed the heteroclinic/homoclinic orbit expansion for the quantum dynamics of fully chaotic systems. Thus, he showed with Eric Heller that semiclassical methods can be extended far beyond the 'log time', which was thought to be an impenetrable barrier. He went on to calculate autocorrelation functions, strength functions, and even chaotic eigen-states. This work he summarized in a Physics Today article "Post-modern quantum mechanics" which generated tremendous interest even outside the field.
Steven Tomsovic established a theory for correlations measured between Coulomb Blockade peak heights in quantum dots. These experiments and their deviations from previous theories were the central issue for quantum chaos and mesoscopic physics at the time. He showed that correlations result from a form of eigenstate localization due to classical periodic orbits. This led to a theory on the influence of the nature of the dynamics (from the integrable to chaotic) on the residual electron-electron interaction.
Recently, he developed a theory for the fidelity (Lochschmidt echo) relating classical diffusion to the quantum scales. He explained how quantum mechanics achieves enhan-ced stability versus classical expectations, leading to longer coherence times and better reversibility. These insights are of great interest to the fields of quantum decoherence and quantum computation. Beyond that, Steven Tomsovic has applied ideas from quantum chaos to a theory for long range ocean acoustic propagation, with possible applications to global climate monitoring.

Prof. Tomsovic's talk on May 14, 2007
"An irreversibilty paradox in simple chaotic sytems"

http://www.mpipks-dresden.mpg.de/pages/forschung/forschung_gutzwiller.html