Professor Feldman joined the Brown Physics Department in 2003. A graduate of the Moscow Institute of Physics and Technology, he received his Ph. D. from the Landau Institute for Theoretical Physics in 1998. He has done his postdoctoral research at the Weizmann Institute of Science and Argonne National Laboratory. He was a recipient of the Koshland Scholar Award from the Weizmann Institute of Science and CAREER Award from NSF.
Professor Feldman's research focuses on theoretical condensed matter physics with emphasis on strongly correlated electrons in low-dimensional systems, and quenched disorder in hard and soft condensed matter
Professor Feldman's research interests include mesoscopics, strongly correlated electrons, and disordered systems.
Modern technology allows confining semiconductors on the nanoscale in one or two dimensions. As we now know, the states of matter formed by electrons in such confined systems cannot be described as one- and two-dimensional analogs of electronic matter in three-dimensional semiconductors. The understanding of those novel states and the transitions between them is one of the key problems in condensed matter physics. The fractional quantum Hall effect provides a striking example. In quantum Hall systems electrons split into several pieces which are neither conventional fermions nor bosons and whose charge is a fraction of the electron charge. One of the directions of Professor Feldman's research is an attempt to understand how the fractionally charged particles propagate and what happens at the phase transitions between quantum Hall phases with different fractional charges. A very interesting question concerns quantum Hall systems with filling factor 5/2. They might exhibit non-Abelian statistics and open a road to the practical implementation of quantum computing.
Another related direction of Professor Feldman's research program is the physics of quantum wires. As the dimensions of electronic
devices scale down, the diameter of wires approaches the electron wavelength. At such scales the intuition based on macroscopic electrodynamics ceases to work and remarkable new physics emerges. Professor Feldman's work focuses on spin and charge transport in non-equilibrium conditions, e. g., in the presence of time-dependent fields. The competition of non-equilibrium effects with strong electron interaction results in very unusual behavior. For example, as professor Feldman has shown, an impurity which backscatters incoming electrons can enhance the current in the forward direction.
The third research direction of Professor Feldman's group is disorder effects in condensed matter. Theorists like idealized models of perfectly uniform crystals, but in the real world impurities are inevitably present. Recently Professor Feldman worked in the field of random porous media. Random porous media such as soil are present everywhere. What happens when a porous matrix confines complex liquid? Experiments with liquid crystals have shown that the usual phases such as nematics and smectics are destroyed in the confinement. The common feature of all liquid crystalline states observed in random media is slow dynamics that resembles relaxation in glasses. Professor Feldman was able to obtain a detailed description of the glassy phase formed by nematic liquid crystals. The random-field Ising model and quantum Hall plateau transitions are closely related problems.
Salomon Research Award, Brown University, "Spin Transport in Quantum Wires", 2006-2007
CAREER award, NSF, "Non-Equilibrium Transport and Disorder Effects in Quantum Wires and Related Systems", 2006-2012.
BSF grant, "Probing Fractional Statistics and Coherence with Anyonic Mach-Zehnder Interferometer", 2007-2011.
NSF grant, Statistics and dynamics in topological states of matter, Principal investigator, 2012-Present