Simulation of three supersonic transport configurations with the Boeing 367-80 in-flight dynamic simulation airplane

In-flight dynamic simulator used to evaluate problems of low-speed approach and landing of supersonic transpor

Operation speed of polariton condensate switches gated by excitons

We present a time-resolved photoluminescence (PL) study in real- and momentum-space of a polariton condensate switch in a quasi-1D semiconductor microcavity. The polariton flow across the ridge is gated by excitons inducing a barrier potential due to repulsive interactions. A study of the device operation dependence on the power of the pulsed gate beam obtains a satisfactory compromise for the ON/OFF-signal ratio and -switching time of the order of 0.3 and $\thicksim50$ ps, respectively. The opposite transition is governed by the long-lived gate excitons, consequently the OFF/ON-switching time is $\thicksim200$ ps, limiting the overall operation speed of the device to $\thicksim3$ GHz. The experimental results are compared to numerical simulations based on a generalized Gross-Pitaevskii equation, taking into account incoherent pumping, decay and energy relaxation within the condensate.Comment: 11 pages, 11 figure

Spin Selective Filtering of Polariton Condensate Flow

Spin-selective spatial filtering of propagating polariton condensates, using a controllable spin-dependent gating barrier, in a one-dimensional semiconductor microcavity ridge waveguide is reported. A nonresonant laser beam provides the source of propagating polaritons while a second circularly polarized weak beam imprints a spin dependent potential barrier, which gates the polariton flow and generates polariton spin currents. A complete spin-based control over the blocked and transmitted polaritons is obtained by varying the gate polarization.Comment: 5 pages, 4 figure

Energy relaxation of exciton-polariton condensates in quasi-1D microcavities

We present a time-resolved study of energy relaxation and trapping dynamics of polariton condensates in a semiconductor microcavity ridge. The combination of two non-resonant, pulsed laser sources in a GaAs ridge-shaped microcavity gives rise to profuse quantum phenomena where the repulsive potentials created by the lasers allow the modulation and control of the polariton flow. We analyze in detail the dependence of the dynamics on the power of both lasers and determine the optimum conditions for realizing an all-optical polariton condensate transistor switch. The experimental results are interpreted in the light of simulations based on a generalized Gross-Pitaevskii equation, including incoherent pumping, decay and energy relaxation within the condensate.Comment: 15 pages, 20 figure

Dynamics of a polariton condensate transistor switch

We present a time-resolved study of the logical operation of a polariton condensate transistor switch. Creating a polariton condensate (source) in a GaAs ridge-shaped microcavity with a non-resonant pulsed laser beam, the polariton propagation towards a collector, at the ridge edge, is controlled by a second weak pulse (gate), located between the source and the collector. The experimental results are interpreted in the light of simulations based on the generalized Gross-Pitaevskii equation, including incoherent pumping, decay and energy relaxation within the condensate.Comment: 4 pages, 2 figure

Optical control of spin textures in quasi-one-dimensional polariton condensates

We investigate, through polarization-resolved spectroscopy, the spin transport by propagating polariton condensates in a quasi one-dimensional microcavity ridge along macroscopic distances. Under circularly polarized, continuous-wave, non-resonant excitation, a sinusoidal precession of the spin in real space is observed, whose phase depends on the emission energy. The experiments are compared with simulations of the spinor-polariton condensate dynamics based on a generalized Gross-Pitaevskii equation, modified to account for incoherent pumping, decay and energy relaxation within the condensate.Comment: 10 pages, 9 figure

Observational properties of massive black hole binary progenitors

The first directly detected gravitational waves (GW 150914) were emitted by two coalescing black holes (BHs) with masses of ~36Msun and ~29Msun. Several scenarios have been proposed to put this detection into an astrophysical context. The evolution of an isolated massive binary system is among commonly considered models. Various groups have performed detailed binary-evolution calculations that lead to BH merger events. However, the question remains open as to whether binary systems with the predicted properties really exist. The aim of this paper is to help observers to close this gap by providing spectral characteristics of massive binary BH progenitors during a phase where at least one of the companions is still non-degenerate. Stellar evolution models predict fundamental stellar parameters. Using these as input for our stellar atmosphere code (PoWR), we compute a set of models for selected evolutionary stages of massive merging BH progenitors at different metallicities. The synthetic spectra obtained from our atmosphere calculations reveal that progenitors of massive BH merger events start their lives as O2-3V stars that evolve to early-type blue supergiants before they undergo core-collapse during the Wolf-Rayet phase. When the primary has collapsed, the remaining system will appear as a wind-fed high-mass X-ray binary. We provide feedback parameters, broad band magnitudes, and spectral templates that should help to identify such binaries in the future. Comparisons of empirically determined mass-loss rates with those assumed by evolution calculations reveal significant differences. The consideration of the empirical mass-loss rates in evolution calculations will possibly entail a shift of the maximum in the predicted binary-BH merger rate to higher metallicities, that is, more candidates should be expected in our cosmic neighborhood than previously assumed.Comment: 64 pages, 30 figures, accepted for publication in Astronomy & Astrophysics, v2: typos correcte

Absence of the Rashba effect in undoped asymmetric quantum wells

To an electron moving in free space an electric field appears as a magnetic field which interacts with and can reorient the electron spin. In semiconductor quantum wells this spin-orbit interaction seems to offer the possibility of gate-voltage control in spintronic devices but, as the electrons are subject to both ion-core and macroscopic structural potentials, this over-simple picture has lead to intense debate. For example, an externally applied field acting on the envelope of the electron wavefunction determined by the macroscopic potential, underestimates the experimentally observed spin-orbit field by many orders of magnitude while the Ehrenfest theorem suggests that it should actually be zero. Here we challenge, both experimentally and theoretically, the widely held belief that any inversion asymmetry of the macroscopic potential, not only electric field, will produce a significant spin-orbit field for electrons. This conclusion has far-reaching consequences for the design of spintronic devices while illuminating important fundamental physics.Comment: 7 pages, 5 fig

VFTS 243 as predicted by the BPASS fiducial models

The recent discovery of an unambiguous quiescent BH and main sequence O star companion in VFTS 243 opens the door to new constraints on theoretical stellar evolution and population models looking to reproduce the progenitors of black hole - black hole binaries. Here we show that the Binary Population and Spectral Synthesis fiducial models (BPASSv2.2.1) natively predict VFTS 243-like systems: We find that VFTS 243 likely originated from a binary system in a \about 15 day orbit with primary mass ranging from 40 to 50 \msol\, and secondary star with initial mass 24--25\msol. %BPASS systems with initial parameters similar to the ones inferred in the discovery paper result in a final system with an O star 10\msol more massive than indicated by the observations. Additionally we find that the death of the primary star must have resulted in a low energy explosion $E<10^{50}$ ergs. With a uniform prior we find that the kick velocity of the new-born black hole was $<33$ \kms (90 percent credible interval). The very low eccentricity reported for VFTS~243 and the subsequent conclusion by the authors that the SN kick must have been very small is in line with the peak in the posterior distribution between 0 and 5 \kms. Finally, the reduced Hobbs kick distribution commonly used in black hole population synthesis is strongly disfavoured, whereas the Bray kick with the most recent parameter calibration predicts 2 $\pm$ 3.5 \kms, which is very consistent with the posterior velocity distributions obtained for our matching VFTS 243-like models using a uniform kick prior.Comment: 3 figures, 1 table, submitted to MNRA