Condensed Matter Theory
(949) 824-5943
Professor Maradudin earned his B.S. degree from Stanford University in 1953 and his Ph.D. from the University of Bristol (England) in 1957. After four years at the University of Maryland, College Park, as a postdoctoral fellow and assistant research professor, and five years at the Westinghouse Research Laboratories, he joined the UCI Physics Department in 1965.
A large part of the research activity in my group is devoted to the theoretical study of surface phenomena.
A primary area of interest is the scattering of electromagnetic waves from randomly rough surfaces. One of the objects of study in this field is the phenomenon of enhanced backscattering, which is the presence of a well-defined peak in the retroreflection direction in the angular dependence of the intensity of the diffuse component of the scattered light. It is caused by the coherent interference between each multiply- scattered optical path and its time-reversed partner. Most of the existing calculations of this effect by computer simulations have been carried out for one-dimensional random surfaces. A major effort is currently underway to extend these calculations to two-dimensional surfaces.
Anharmonic properties of a surface phonon, such as the shift in its frequency with increasing temperature and the temperature dependence of its lifetime, due to phonon-phonon interactions, are being studied in the classical regime of high temperature by molecular dynamics simulations. In the low temperature regime, where quantum effects are important, path integral quantum Monte Carlo methods are being used to calculate static (thermodynamic) and dynamic properties of anharmonic crystals. In addition to providing nonperturbative results for fundamental vibrational properties of crystals, such calculations provide benchmarks against which the results of perturbative and other approximate calculations can be compared.
We have recently been carrying out calculations of the dispersion curves of electromagnetic waves propagating through two and three dimensional, periodic, dielectric structures. They possess gaps in certain frequency ranges. Electromagnetic waves with frequencies in these ranges cannot exist. This has the consequence that spontaneous emission is forbidden in cases in which the band gap overlaps the electronic band edge, which can improve the performance of many optical and electronic devices. The absence of electromagnetic modes in a certain frequency range can also modify the basic properties of many atomic, molecular, and excitonic systems.
General theories of wave propagation through a disordered medium predict their confinement to a limited region of the medium caused by the strong, multiple scattering of the waves by the random spatial fluctuations of the material properties of the medium. This effect has yet to be observed experimentally, and we are trying to elucidate conditions particularly favorable for its observation. We have shown recently that electromagnetic waves are confined to a smaller region of a random two-dimensional dielectric medium that is periodic on average when their frequency lies in a gap in the dispersion curves of the average periodic medium than when their frequency is outside it.
As a teacher, I believe that my role is not only to transmit information to my students but also to teach them how to think, to reason. The latter is more difficult, both for the teacher and for the student, than the former, but ultimately more rewarding, since the knowledge a student receives will change with time, particularly in a rapidly evolving field such as physics, but the ability to reason transcends such changes.