Semiconductor Cavity QED

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Cavity quantum electrodynamics (QED), one of the most curious and fundamental aspects of AMO physics, explores quantum dynamical processes for individual quantum objects coupled to the resonator's electromagnetic field: Purcell effect, entanglement, quantum/classical boundary, quantum information science, and quantum teleportation. The biggest experimental bottleneck for atomic cavity QED is the movement of the atom, only recently reduced, but not stopped, by cooling and trapping. Now a semiconductor system has a chance to be better than its atomic counterpart. The cavity QED photonic crystal cavity volume is near the minimum possible for a dielectric, the quality factor is very high, and the quantum dot "atom" does not move. Moreover the structure is totally integrated, i.e., it stays together, so it can be used over and over again. This project focuses on this emerging capability to investigate a solid-state nanosystem (cavity/dot) where individual quanta play decisive roles. This group, the first in the world to see vacuum Rabi splitting due to coupling between a single semiconductor quantum dot and a photonic crystal nanocavity, is exploring two research areas. The first target area is an investigation of the effect of atomic layer deposition of titanium oxide upon the surfaces of silicon nanobeam cavities and GaAs photonic crystal nanocavities. The quality factors of several cavities are being measured before and after the deposition in order to gather statistics on its effect. Success with GaAs-based cavities could be one way to reduce the coupled-system linewidths now dominated by cavity decay rates. The other target area is an alteration of the observed coupling between an array of silver split-ring resonators and a quantum well grown very close to the surface on which the array is fabricated. The dependence of the coupling upon separation between the quantum well and split-ring resonators will be studied at low temperature by pump-probe spectroscopy. This study is part of the PI's general interest in the acceleration of the radiative decay of semiconductor nanostructures by a nearby sub-wavelength metallic structure, as originally suggested by Purcell in his famous paper. This project provides training to graduate students on state-of-the-art instrumentation from nanotechnology to laser technology.