Electrical control of hole spin relaxation in charge tunable InAs/GaAs quantum dots

We report on optical orientation of singly charged excitons (trions) in charge-tunable self-assembled InAs/GaAs quantum dots. When the charge varies from 0 to -2, the trion photoluminescence of a single quantum dot shows up and under quasiresonant excitation gets progressively polarized from zero to approximately 100%. This behavior is interpreted as the electric control of the trion thermalization process, which subsequently acts on the hole-spin relaxation driven in nanosecond time scale by the anisotropic electron-hole exchange. This is supported by the excitation spectroscopy and time-resolved measurements of a quantum dot ensemble.     

Experimental investigation of amplitude and phase quantum correlations in a type II optical parametric oscillator above threshold: from nondegenerate to degenerate operation

We describe a stable type II optical parametric oscillator operated above threshold that provides 9.7 +/- 0.5 dB (89%) of quantum noise reduction on the intensity difference of the signal and idler modes. We also report the first experimental study, to our knowledge, by homodyne detection of the generated bright two-mode state in the case of frequency-degenerate operation obtained by the introduction of a birefringent plate inside an optical cavity.     

Equilateral Dimension of the Rectilinear Space

Itis conjectured that there exist at most 2k equidistantpoints in the k-dimensional rectilinear space.This conjecture has been verified for k ≤ 3; we show here its validity in dimension k = 4. We alsodiscuss a number of related questions. For instance, what isthe maximum number of equidistant points lying in the hyperplane: $\sum\nolimits_{i = 1}^k {x_i } = 0?$ If this number would be equal to k, then the above conjecture would follow. Weshow, however, that this number is ≥ k + 1 for k ≥ 4.     

Selective alkylation of a 6,7-dihydroxyquinazoline

A convenient 3-step multi-parallel process for the preparation of 4-(3-chloro-2-fluoroanilino)-6,7-bisalkoxyquinazolines is highlighted.     

Structure of the bromination product of 2-ethyl-1,4-benzothiazin-3(4H)-one

2-Ethyl-1,4-benzothiazin-3(4H)-one and bromine react smoothly to give Z-2-(1-bromoethylidine)-2(H)-1,4-benzothiazin-3(4H)-one, which results from a complex bromination-oxidation sequence. The structure of this product was determined by an X-ray study.     

Novel transition metal phospha-alkyne complexes: tBuCP acting as a 6 electron donor ligand. Synthesis,crystal and molecular structure of [Co2(CO)6(μ-tBuCP)W(CO)5]

A single crystal X-ray diffraction study of [Co₂(CO)₆(μ-^tBuCP)W(CO)₅] establishes that phospha-alkyne behaves as a 6e donor. Synthesis of the related [(η⁵-C₅H₅)₂Mo₂(CO)₄(μ-^tBuCP)W(CO)₅] complex is reported.