The negative Bogoliubov dispersion in exciton-polariton condensates

Bogoliubov's theory states that self-interaction effects in Bose-Einstein condensates produce a characteristic linear dispersion at low momenta. One of the curious features of Bogoliubov's theory is that the new quasiparticles in the system are linear combinations of creation and destruction operators of the bosons. In exciton-polariton condensates, this gives the possibility of directly observing the negative branch of the Bogoliubov dispersion in the photoluminescence (PL) emission. Here we theoretically examine the PL spectra of exciton-polariton condensates taking into account of reservoir effects. At sufficiently high excitation densities, the negative dispersion becomes visible. We also discuss the possibility for relaxation oscillations to occur under conditions of strong reservoir coupling. This is found to give a secondary mechanism for making the negative branch visible

Mechanical properties of magnesium based amorphous alloys produced by powder metallurgy

The newly developed "clean process" enabled safe atomization and consolidation of fine Mg base alloy powders. Amorphous Mg75Cu5Y75 and Mg, ,Ca ..Al.„. powders (smaller than 25 ¡1 mj were extruded at 673 K above Tx. They showed a mixed structure consisting of Mg24Y5+Mg2Cu and ALCa respectively dispersed in a hcp-Mg matrix. The tensile strengths for the bulk MgS75Cu5Y75 and Mg70Ca10AI0 alloys are 740 MPa and 600 MPa at 298 K respectively which are about twice as high as the highest value for conventional Mg alloys. The high strengths are presumably due to the formation of the fine microstructure consisting of nanoscale intermetallic compound particulates homogeneously embedded in the Mg matrix with a fine grain size. These data allow us to expect that the newly developed Mg-based alloys will proceed hereafter as a new type of high specific strength material

Anastrozole-related acute hepatitis with autoimmune features: a case report

<p>Abstract</p> <p>Background</p> <p>Two cases of acute hepatitis occurring during treatment with anastrozole have previously been reported, but the underlying mechanisms of liver injury are still uncertain. We report the case of anastrozole-related acute hepatitis with some autoimmune features.</p> <p>Case presentation</p> <p>A 70-year-old woman developed acute hepatitis associated with serum antinuclear antibodies during anastrozole treatment; after drug withdrawal, liver function parameters rapidly improved and serum auto-antibodies were no longer detectable.</p> <p>Conclusions</p> <p>Anastrozole-induced hepatotoxicity is a very rare event. Drug-drug interactions or metabolically-mediated damage might be involved, with a possible role of individual susceptibility. Our report suggests that an immune-mediated mechanism may also be considered in anastrozole-related liver injury.</p

Two-photon interference at telecom wavelengths for time-bin-encoded single photons from quantum-dot spin qubits

This work was supported by the JST through its ImPACT Program, NICT, NSF CCR-08 29694, NIST 60NANB9D9170, Special Coordination Funds for Promoting Science and Technology, and the State of Bavaria. C.L. and M.M.F. acknowledge support through the AFOSR. C.M.N. acknowledges a SU2P Entrepreneurial Fellowship and R.H.H. acknowledges a Royal Society University Research Fellowship.Practical quantum communication between remote quantum memories rely on single photons at telecom wavelengths. Although spin-photon entanglement has been demonstrated in atomic and solid-state qubit systems, the produced single photons at short wavelengths and with polarization encoding are not suitable for long-distance communication, because they suffer from high propagation loss and depolarization in optical fibres. Establishing entanglement between remote quantum nodes would further require the photons generated from separate nodes to be indistinguishable. Here, we report the observation of correlations between a quantum-dot spin and a telecom single photon across a 2-km fibre channel based on time-bin encoding and background-free frequency downconversion. The downconverted photon at telecom wavelengths exhibits two-photon interference with another photon from an independent source, achieving a mean wavepacket overlap of greater than 0.89 despite their original wavelength mismatch (900 and 911 nm). The quantum-networking operations that we demonstrate will enable practical communication between solid-state spin qubits across long distances.Publisher PDFPeer reviewe