A Light-Hole Germanium Quantum Well on Silicon.

The quiet quantum environment of holes in solid-state devices is at the core of increasingly reliable architectures for quantum processors and memories. However, due to the lack of scalable materials to properly tailor the valence band character and its energy offsets, the precise engineering of light-hole (LH) states remains a serious obstacle toward coherent optical photon-spin interfaces needed for a direct mapping of the quantum information encoded in photon flying qubits to stationary spin processors. Herein, to alleviate this long-standing limitation, an all-group-IV low-dimensional system is demonstrated, consisting of a highly tensile strained germanium quantum well grown on silicon allowing new degrees of freedom to control and manipulate the hole states. Wafer-level, high bi-isotropic in-plane tensile strain (<1%) is achieved using strain-engineered, metastable germanium-tin alloyed buffer layers yielding quantum wells with LH ground state, high g-factor anisotropy, and a tunable splitting of the hole sub-bands. The epitaxial heterostructures display sharp interfaces with sub-nanometer broadening and show room-temperature excitonic transitions that are modulated and extended to the mid-wave infrared by controlling strain and thickness. This ability to engineer quantum structures with LH selective confinement and controllable optical response enables manufacturable silicon-compatible platforms relevant to integrated quantum communication and sensing technologies.

Diagnostic performance of thromboelastometry in trauma-induced coagulopathy: a comparison between two level I trauma centres using two different devices.

PURPOSE: The implementation of a ROTEM®-based algorithm requires reliable thresholds to mirror a prothrombin time (PT) ratio > 1.2 and/or a fibrinogen concentration < 1.5 g l-1. Our goal was to compare the diagnostic performances of two devices (ROTEM® Sigma and Delta, IL Werfen, Munich, Germany) in two level-I trauma centres for the diagnostic of post-traumatic coagulopathy. METHODS: We conducted a retrospective analysis of two registries across two periods of time: from September 2014 to December 2015 in Lyon-Sud university trauma centre and from April 2016 to January 2018 in the Grenoble Alps Trauma Centre. Accuracies of EXTEM and FIBTEM assays to detect patients with coagulation disorders were tested for each device using receiver operating characteristic (ROC) analyses. RESULTS: Within the study period, 74 trauma patients in the Grenoble cohort and 75 trauma patients in the Lyon cohort had concomitant ROTEM® and standard coagulation testing on admission. No statistically significant difference was found between the two ROC curves for FIBTEM amplitude at 5 min (A5), FIBTEM maximum clot firmness, EXTEM clotting time (CT) and EXTEM A5 for ROTEM® Sigma and Delta to diagnose post-traumatic coagulation disorders. The best threshold for FIBTEM A5 to predict low fibrinogen concentration was 7 mm for each device. EXTEM CT thresholds to diagnose PT ratio > 1.2 were 78 s and 74 s for ROTEM® Sigma and Delta, respectively. CONCLUSIONS: These results suggest that ROTEM®-based algorithms may be transposed from one trauma centre to another independently of the setting and the ROTEM® device in use.