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.
Ullmo, D., and H. U. Baranger. “Wireless propagation in buildings: a statistical scattering approach.” Ieee Transactions on Vehicular Technology, vol. 48, no. 3, Jan. 1999, pp. 947–55. Scopus, doi:10.1109/25.765025. Full Text
Narimanov, E. E., et al. “Chaos in quantum dots: Dynamical modulation of coulomb blockade peak heights.” Physical Review Letters, vol. 83, no. 13, Jan. 1999, pp. 2640–43. Scopus, doi:10.1103/PhysRevLett.83.2640. Full Text
Mello, P. A., and H. U. Baranger. “Interference phenomena in electronic transport through chaotic cavities: An information-theoretic approach.” Latin American School of Physics Xxxi Elaf, edited by S. Hacyan et al., vol. 464, AMER INST PHYSICS, Jan. 1999, pp. 281–333.
Narimanov, E. E., et al. “Anomalous low temperature behavior of superconducting Nd1.85Ce0.15CuO4-y.” Physical Review Letters, vol. 83, no. 13, 1999, pp. 2644–47.
Ullmo, D., et al. “Chaos and interacting electrons in ballistic quantum dots.” Physical Review Letters, vol. 80, no. 5, Jan. 1998, pp. 895–99. Scopus, doi:10.1103/PhysRevLett.80.895. Full Text
Ullmo, D., et al. “Semiclassical approach to orbital magnetism of interacting diffusive quantum systems.” Physica E: Low Dimensional Systems and Nanostructures, vol. 1, no. 1–4, Jan. 1997, pp. 268–73.
Hasen, J., et al. “Large excitonic confinement in asymmetric quantum T wires.” Superlattices and Microstructures, vol. 22, no. 3, Jan. 1997. Scopus, doi:10.1006/spmi.1996.0283. Full Text
Gopar, V. A., et al. “The invariant measure for scattering matrices with block symmetries.” Journal of Physics A: Mathematical and General, vol. 29, no. 4, Dec. 1996, pp. 881–88. Scopus, doi:10.1088/0305-4470/29/4/014. Full Text
Baranger, H. U., and P. A. Mello. “Reflection symmetric ballistic microstructures: Quantum transport properties.” Physical Review. B, Condensed Matter, vol. 54, no. 20, Nov. 1996, pp. R14297–300. Epmc, doi:10.1103/physrevb.54.r14297. Full Text
Matveev, K. A., et al. “Coulomb blockade of tunneling through a double quantum dot.” Physical Review. B, Condensed Matter, vol. 54, no. 8, Aug. 1996, pp. 5637–46. Epmc, doi:10.1103/physrevb.54.5637. Full Text