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.
Woodward, T. K., et al. “Sequential versus coherent tunneling in double-barrier diodes investigated by differential absorption spectroscopy.” Physical Review. B, Condensed Matter, vol. 44, no. 3, July 1991, pp. 1353–56. Epmc, doi:10.1103/physrevb.44.1353. Full Text
Nixon, J. A., et al. “Breakdown of quantized conductance in point contacts calculated using realistic potentials.” Physical Review. B, Condensed Matter, vol. 43, no. 15, May 1991, pp. 12638–41. Epmc, doi:10.1103/physrevb.43.12638. Full Text
Behringer, R., et al. “Quantum-mechanical features in the resistance of a submircon junction.” Physical Review Letters, vol. 66, no. 7, Feb. 1991, pp. 930–33. Epmc, doi:10.1103/physrevlett.66.930. Full Text
Nixon, J. A., et al. “Conductance of quantum point contacts calculated using realistic potentials.” Superlattices and Microstructures, vol. 9, no. 2, Jan. 1991, pp. 187–90. Scopus, doi:10.1016/0749-6036(91)90280-5. Full Text
Woodward, T. K., et al. “Sequential vs. coherent tunneling in double barrier diodes investigated by differential absorption spectroscopy.” Technical Digest International Electron Devices Meeting, Dec. 1990, pp. 959–62.
Baranger, H. U. “Multiprobe electron waveguides: Filtering and bend resistances.” Physical Review. B, Condensed Matter, vol. 42, no. 18, Dec. 1990, pp. 11479–95. Epmc, doi:10.1103/physrevb.42.11479. Full Text
Jalabert, R. A., et al. “Conductance fluctuations in the ballistic regime: A probe of quantum chaos?” Physical Review Letters, vol. 65, no. 19, Nov. 1990, pp. 2442–45. Epmc, doi:10.1103/physrevlett.65.2442. Full Text
Baranger, H. U., and A. D. Stone. “Geometrical effects on the Hall resistance in ballistic microstructures.” Surface Science, vol. 229, no. 1–3, Apr. 1990, pp. 212–15. Scopus, doi:10.1016/0039-6028(90)90873-7. Full Text
Behringer, R. E. “One-dimensional ballistic transport in AlGaAs/GaAs electron waveguides.” Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, vol. 7, no. 6, American Vacuum Society, Nov. 1989, pp. 2039–2039. Crossref, doi:10.1116/1.584644. Full Text
Baranger, H. U., and A. D. Stone. “Electrical linear-response theory in an arbitrary magnetic field: A new Fermi-surface formation.” Physical Review. B, Condensed Matter, vol. 40, no. 12, Oct. 1989, pp. 8169–93. Epmc, doi:10.1103/physrevb.40.8169. Full Text