Harold U. Baranger
Professor of Physics
The broad focus of Prof. Baranger's group is quantum open systems at the nanoscale, particularly the generation of correlation between particles in such systems. Fundamental interest in nanophysics-- the physics of small, nanometer scale, bits of solid-- stems from the ability to control and probe systems on length scales larger than atoms but small enough that the averaging inherent in bulk properties has not yet occurred. Using this ability, entirely unanticipated phenomena can be uncovered on the one hand, and the microscopic basis of bulk phenomena can be probed on the other. Additional interest comes from the many links between nanophysics and nanotechnology. Within this thematic area, our work ranges from projects trying to nail down realistic behavior in well-characterized systems, to more speculative projects reaching beyond regimes investigated experimentally to date.
Correlations between particles are a central issue in many areas of condensed matter physics, from emergent many-body phenomena in complex materials, to strong matter-light interactions in quantum information contexts, to transport properties of single molecules. Such correlations, for either electrons or bosons (photons, plasmons, phonons,…), underlie key phenomena in nanostructures. Using the exquisite control of nanostructures now possible, experimentalists will be able to engineer correlations in nanosystems in the near future. Of particular interest are cases in which one can tune the competition between different types of correlation, or in which correlation can be tunably enhanced or suppressed by other effects (such as confinement or interference), potentially causing a quantum phase transition-- a sudden, qualitative change in the correlations in the system.
My recent work has addressed correlations in both electronic systems (quantum wires and dots) and photonic systems (photon waveguides). We have focused on 3 different systems: (1) qubits coupled to a photonic waveguide, (2) quantum dots in a dissipative environment, and (3) low-density electron gas in a quantum wire. The methods used are both analytical and numerical, and are closely linked to experiments.
Hentschel, M., et al. “Fermi edge singularities in the mesoscopic regime: Anderson orthogonality catastrophe.” Physical Review B Condensed Matter and Materials Physics, vol. 72, no. 3, July 2005. Scopus, doi:10.1103/PhysRevB.72.035310. Full Text
Miller, M., et al. “Statistics of wave functions in disordered systems with applications to Coulomb blockade peak spacing.” Physical Review B Condensed Matter and Materials Physics, vol. 72, no. 4, July 2005. Scopus, doi:10.1103/PhysRevB.72.045305. Full Text
Lee, J. W., et al. “Quantum Monte Carlo study of disordered fermions.” Physical Review B Condensed Matter and Materials Physics, vol. 72, no. 2, July 2005. Scopus, doi:10.1103/PhysRevB.72.024525. Full Text
Getty, S. A., et al. “Near-perfect conduction through a ferrocene-based molecular wire.” Physical Review B Condensed Matter and Materials Physics, vol. 71, no. 24, June 2005. Scopus, doi:10.1103/PhysRevB.71.241401. Full Text
Ghosal, A., et al. “Interaction effects in the mesoscopic regime: A quantum Monte Carlo study of irregular quantum dots.” Physical Review B Condensed Matter and Materials Physics, vol. 71, no. 24, June 2005. Scopus, doi:10.1103/PhysRevB.71.241306. Full Text
Yoo, Jaebeom, et al. “Multilevel algorithm for quantum-impurity models..” Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics, vol. 71, no. 3 Pt 2B, Mar. 2005. Epmc, doi:10.1103/physreve.71.036708. Full Text
Ke, S. H., et al. “Electron transport through molecules: Gate-induced polarization and potential shift.” Physical Review B Condensed Matter and Materials Physics, vol. 71, no. 11, Mar. 2005. Scopus, doi:10.1103/PhysRevB.71.113401. Full Text
Jiang, H., et al. “Scrambling and gate-induced fluctuations in realistic quantum dots.” Physical Review B Condensed Matter and Materials Physics, vol. 71, no. 8, Feb. 2005. Scopus, doi:10.1103/PhysRevB.71.085313. Full Text
Ke, San-Huang, et al. “Contact atomic structure and electron transport through molecules..” The Journal of Chemical Physics, vol. 122, no. 7, Feb. 2005. Epmc, doi:10.1063/1.1851496. Full Text
Ullmo, D., et al. “Interactions and broken time-reversal symmetry in chaotic quantum dots.” Physical Review B Condensed Matter and Materials Physics, vol. 71, no. 20, Jan. 2005. Scopus, doi:10.1103/PhysRevB.71.201310. Full Text