MBE growth of multiple quantum wells with room-temperature exciton peaks at 1.3 μm

multiple quantum wells have been grown lattice matched on InP substrates by taking into account the time dependence of the fluxes as the shutters open and close. RHEED oscillations are observed and used to calibrate layer thicknesses and growth quality. The half width of the lowest exciton peak is 12 meV.     

Entanglement between a photon and a quantum well

The lack of translational invariance perpendicular to the plane of a single quantum well causes equal probability for spontaneous emission to the left or right. Combining one emission path from the left and one from the right into a common detector leads to interference fringes for fundamentally indistinguishable paths corresponding to geometries where the same in-plane momentum is transferred to the quantum well. For all other paths, no interference is observed because of the entanglement between the photon and extended Bloch states of the many-body system. In multiple-quantum-well structures the interference can be controlled via the spacing between the wells.     

Weak localization of light in a disordered microcavity

We report the observation of weak localization of light in a semiconductor microcavity. The intrinsic disorder in a microcavity leads to multiple scattering and hence to static speckle. We show that averaging over realizations of the disorder reveals a coherent backscattering cone that has a coherent enhancement factor > or =2, as required by reciprocity. The coherent backscattering cone is observed along a ring-shaped pattern due to confinement by the microcavity.     

Quantum correlations in the nonperturbative regime of semiconductor microcavities

The nonlinear optical response of semiconductor microcavities in the nonpertubative regime is studied in resonant single-beam-transmission and pump-probe experiments. In both cases a pronounced third transmission peak lying spectrally between the two normal modes is observed. A fully quantized theory is essential for the agreement with the experimental observations, demonstrating that quantum fluctuations leading to intraband polarizations are responsible for this effect.     

Erbium-induced interdiffusion of gallium and aluminum in GaAs/AlGaAs quantum-well structures

Incorporation of erbium into GaAs/AlGaAs quantum-well structures in the course of their MBE growth has been shown experimentally to initiate effective Ga and Al interdiffusion and Er diffusion due to the erbium-induced enhanced vacancy formation. A mechanism for the formation of cation vacancies is proposed, which is based on the generation of local strains by the incorporating erbium. It is shown that erbium interacts with aluminum to produce in AlGaAs aluminum-enriched, erbium-containing clusters. Fiz. Tverd. Tela (St. Petersburg) 41, 540–544 (March 1999)     

Reaction of chloromercuriocobaltacarborane with derivatives of the undecaborate anion

The reactions of the undecaborate anion Cs⁺C₂B₉H₁₂ ^– (1) and exo-nido-ruthenacarborane exo-nido-5,6,10-[Cl(Ph₃P)₂Ru]-5,6,10-(-H)₃-10-H-7,8-C₂B₉H₈ (2) with the 9-chloromercurated cobaltacarborane, viz., 3-(⁵-Cp)-9-ClHg-3,1,2-CoC₂B₉H₁₀ (3), afforded Cs[10-{3"-(⁵-Cp)-3",1",2"-CoC₂B₉H₁₀-9"-Hg}-7,8-C₂B₉H₁₁] (4) and 5,6,10-exo-nido-[Cl(Ph₃P)₂Ru]-5,6,10-(-H)₃-10-{3"-(⁵-Cp)-3",1",2"-CoC₂B₉H₁₀-9"-Hg}-7,8-C₂B₉H₈ (5), respectively. The latter compound exists as two isomers. Compound 5 was prepared also by the reaction of compound 4 with Ru(PPh₃)₃Cl₂.