Yale Physics Professor Receives Alexander von Humboldt Award

Yoram Alhassid, Yale professor of physics, has received the prestigious Alexander von Humboldt Senior Scientist Award, which is given to “scholars with internationally recognized academic qualifications. The award is intended as a lifelong tribute to the past academic accomplishments of award winners.”

Award winners are invited to carry out research projects of their own choice in Germany for periods of between six months and one year.

Alhassid was noted for his important contributions to many-body theory, in particular for his work on the maximum entropy approach, on the quantum Monte Carlo calculations, on chaotic phenomena in nuclei, and on the transport properties of mesoscopic samples.

“My work is focused on developing novel methods for understanding the statistical properties of quantum many-body systems, including atomic nuclei and quantum dots,” Alhassid said. “Techniques that were introduced in nuclear physics have helped us understand some of the fascinating properties of quantum dots.”

Alhassid and collaborators developed quantum Monte Carlo techniques that enable them to calculate microscopically properties of heavy nuclei that were far beyond the reach of conventional methods or could only be understood with empirical models. These properties are important in astrophysical processes such as the formation of heavy elements in stars (nucleosynthesis) and supernovas. Solving the nuclear many-body problem is difficult because the strong interactions among the particles that make up the nucleus mix a huge number of particle configurations. The power of the Monte Carlo approach is in selecting only the most important configurations.

Quantum dots are man-made devices in which electrons are confined to a tiny region. These systems are so small that at temperatures close to absolute zero they follow the laws of quantum mechanics. “The invention of quantum dots was an important turning point, since it made it possible to explore quantum phenomena in small systems in a way that can be fully controlled by the experimentalist,” said Alhassid. “Quantum dots conduct electricity just like a wire with an on-off switch. The important difference is that in a quantum dot the process of conduction is quantum mechanical.”

Alhassid and collaborators are studying quantum dots that have no particular symmetry. These dots display rich behavior that reflects the interplay of quantum coherence, chaotic dynamics, and electron-electron interactions. Some of their properties are universal and depend only on the underlying fundamental space-time symmetries. Alhassid’s work in Germany will focus on the role of electron-electron interactions in the statistical properties of the conductance of micro- and nanostructures. His hosts are Professor Hans Weidenmüller and Professor Konstantin Efetov.

Alhassid recently was invited to present his work in a Nobel Symposium in Sweden. This summer, he is organizing a 10-week international program at the Institute of Nuclear Theory at the University of Washington, Seattle, on “Chaos and interactions: from nuclei to quantum dots.”