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.
Chang, A. M., et al. “Quenching of the Hall resistance in a novel geometry.” Physical Review Letters, vol. 63, no. 9, Aug. 1989, pp. 996–99. Epmc, doi:10.1103/physrevlett.63.996. Full Text
Baranger, H. U., and A. D. Stone. “Quenching of the Hall resistance in ballistic microstructures: A collimation effect.” Physical Review Letters, vol. 63, no. 4, July 1989, pp. 414–17. Epmc, doi:10.1103/physrevlett.63.414. Full Text
Timp, G., et al. “Suppression of the Aharonov-Bohm effect in the quantized Hall regime.” Physical Review. B, Condensed Matter, vol. 39, no. 9, Mar. 1989, pp. 6227–30. Epmc, doi:10.1103/physrevb.39.6227. Full Text
Chang, A. M., et al. “Erratum: Quenching of the Hall resistance in a novel geometry (Physical Review Letters (1989) 63, 996 (2695)).” Physical Review Letters, vol. 63, no. 24, Jan. 1989, p. 2695. Scopus, doi:10.1103/PhysRevLett.63.2695.4. Full Text
Chang, A. M., et al. “Erratum: Quenching of the Hall resistance in a novel geometry [Phys. Rev. Lett. [bold 63], 996 (1989)].” Phys. Rev. Lett., vol. 63, APS, 1989, pp. 2695–2695.
Timp, G., et al. “Propagation around a bend in a multichannel electron waveguide.” Physical Review Letters, vol. 60, no. 20, May 1988, pp. 2081–84. Epmc, doi:10.1103/physrevlett.60.2081. Full Text
Baranger, H. U., et al. “Resistance fluctuations in multiprobe microstructures: Length dependence and nonlocality.” Physical Review. B, Condensed Matter, vol. 37, no. 11, Apr. 1988, pp. 6521–24. Epmc, doi:10.1103/physrevb.37.6521. Full Text
Chang, A. M., et al. “Real-space and magnetic-field correlation of quantum-resistance fluctuations in the ballistic regime in narrow GaAs-AlxGa.” Physical Review. B, Condensed Matter, vol. 37, no. 5, Feb. 1988, pp. 2745–48. Epmc, doi:10.1103/physrevb.37.2745. Full Text
Baranger, H. U., and J. W. Wilkins. “Ballistic structure in the electron distribution function of small semiconducting structures: General features and specific trends.” Physical Review. B, Condensed Matter, vol. 36, no. 3, July 1987, pp. 1487–502. Epmc, doi:10.1103/physrevb.36.1487. Full Text
Baranger, H. U., et al. “Ballistic peaks in the distribution function from intervalley transfer in a submicron structure.” Applied Physics Letters, vol. 51, no. 21, Jan. 1987, pp. 1708–10. Scopus, doi:10.1063/1.98551. Full Text