Alhassid's research program spans nuclear physics, mesoscopic physics and nanoscience, cold atomic gases, and quantum chaos. A unifying theme is the development of computational and analytical methods for finite-size correlated quantum many-body systems.
Nuclear many-body theory Alhassid and his collaborators researched the development and application of the
auxiliary-field Monte Carlo approach, known as the shell model Monte Carlo (SMMC) method, for the microscopic calculation of nuclear statistical properties. An advance by Alhassid and collaborators was the development of methods to circumvent the
sign problem in SMMC calculations for odd-particle-number nuclei, enabling systematic calculations of ground-state energies for isotopic chains of heavy odd-mass nuclei. The group has also developed methods to extract nuclear spectra from SMMC calculations using imaginary-time correlation matrices, and to study nuclear deformation, shape transitions, and collective excitations in heavy nuclei.
Mesoscopic physics and quantum dots Alhassid and his collaborators developed a statistical theory of
quantum dots that describes the mesoscopic fluctuations of
conductance through quantum dots in terms of the underlying signatures of
quantum chaos in the single-particle electronic wavefunctions. His comprehensive review article on this subject, published in
Reviews of Modern Physics in 2000, drew on tools from
semiclassical physics,
random matrix theory, and the supersymmetric nonlinear sigma model to describe quantum transport through dots in which the electron dynamics are chaotic or diffusive. The group also contributed to the theoretical understanding of ultra-small metallic
nanoparticles in which conventional
BCS theory of
superconductivity breaks down, a regime common to both nanoparticles and nuclei despite their energy gaps differing by six orders of magnitude. == Awards and honors ==