Condensed Matter Theory

Condensed matter physics is the study of the macroscopic and mesoscopic properties of matter. Condensed matter theory seeks to use the well-established laws of microscopic physics to predict the collective and structural properties of large numbers of electrons, atoms or molecules. While the basic laws of the constituent particles are very simple, large numbers of such particles often display surprisingly complex phenomena and emergent behaviors such as superconductivity, magnetism and topological order. Beyond equilibrium properties, the cooperative physics often also lead to complex non-equiibrium properties and dynamics in both quantum and classical condensed matter systems.

The Theoretical Condensed Matter group at the University of Cincinnati has six faculty members listed below, along with a sizable group of students and postdocs. Various sub-fields such as Statistical Physics, Quantum Condensed Matter Physics, Quantum Chaos together with inter-disciplinary applications to Chemical/Biological Physics are well-represented in the group.

Carlos Bolech's interests span several aspects of statistical and solid state physics. A large portion of his research involves complex quantum impurity models and their connections with correlated lattice systems and mesoscopic systems at the nanometer scale. Quantum impurities are one of the current paradigms of strongly correlated systems. Another class of systems of interest are ultracold atomic gases trapped in optical lattices, which can be used to emulate different strongly correlated phases of matter. In turn, dealing with strong interactions is one of the main theoretical challenges of present-day frontier problems not only in condensed-matter physics but also in atomic, nuclear and particle physics. Within condensed-matter physics, strong correlations are to be found in numerous systems such as heavy fermions, high-temperature superconductors, organic conductors, or quantum wires and dots. Bolech's work combines different computational and analytic non-perturbative approaches to problems like the optical response of Mott insulators, the interplay of mixed valence and multi-channel Kondo physics in heavy fermions and quantum dots, tunneling transport in unconventional superconductors, or the study of strongly correlated phases in ultracold atomic gases.

Frank Pinski is developing novel computational algorithms to explore the behavior of molecules, such as chemical reactions or conformation changes. The aim is to learn more about the intermediate states that are visited during such transitions. One would like to sample the transition paths in a thermodynamically significant manner. The motion of the atoms that comprised the molecules is described by Brownian dynamics. The resulting paths are thus continuous but almost nowhere differentiable; a characteristic that means that one has to be careful with the underlying mathematics. At the present time, his group is exploring transitions in small systems; the ultimate goal is to be able to use these algorithms to understand a myriad of diverse problems, such as catalysis and protein folding.

Michael Ma (Emeritus) is researching quantum disordered systems, strongly correlated systems, and quantum phase transitions. Recent work includes metal-insulator transition, superconductor/superfluid-insulator transition, orbitals, spintronics, supersolid, cold atoms and unconventional Cooper pairing, and complex quantum magnets.

Nayana Shah's field of research is Quantum Condensed Matter Physics, with a focus on strongly correlated, mesoscopic and nano-scale systems. The underlying theme in her research has been the study of the effects of strong correlations, quantum and thermal fluctuations, disorder, decoherence, dissipation, and departure from equilibrium, in a variety of condensed-matter systems. These systems encompass complex materials such as heavy fermion compounds, high-temperature superconductors and exotic magnets; low-dimensional/nano-scale superconductors such as thin films and nanowires; and artificially-designed/tunable systems and devices such as magnetic nanostructures, quantum dots and ultra-cold atoms. Her approach to research is to identify and investigate questions of a fundamental nature that are also of experimental relevance and she often actively collaborates with experimental groups in trying to build a coherent understanding of the question at hand.

Rotislav Serota is researching Mesoscopic physics, Quantum chaos, and Non-Linear Dynamics in psychological systems. Much of his recent research involves the level spacing distribution, level correlations, etc.—of energy levels with large quantum numbers (semiclasical quantization) in size-quantized systems.

Tom Beck is a member of the Department of Chemistry, with significant overlap of interests with the Physics CMT group. Beck's research focuses on studies of ion hydration in chemistry and biophysics. His group has several projects ongoing concerning calculations of ion hydration free energies and entropies, and how ions interact with interfaces. An aim is to calculate ion hydration thermodynamic properties at the quantum mechanical level. The fundamental methods developed in previous research are being applied to study ion interactions with membrane protein channels that control the flow of ions into and out of cells. The work involves classical and quantum simulation methods, statistical mechanics, and electrostatics calculations. The overall goal is to approach biophysical systems at a fundamental level to help unravel the intricate mechanisms that control biological processes. A particular focus is on the interesting phenomenon of specific ion effects—variation of the ion identity can have profound impacts on solution phase properties, and his group is trying to understand the origin of these intriguing changes with ion type.