Approach to accurately measuring the speed of optical precursors

Precursors can serve as a bound on the speed of information with dispersive medium. We propose a method to identify the speed of optical precursors using polarization-based interference in a solid-state device, which can bound the accuracy of the precursors' speed to less than $10^{-4}$ with conventional experimental conditions. Our proposal may have important implications for optical communications and fast information processing.Comment: 4 pages, 4 figure

Experimental detection of quantum coherent evolution through the violation of Leggett-Garg-type inequalities

We discuss the use of inequalities of the Leggett-Garg type (LGtI) to witness quantum coherence and present the first experimental violation of this type of inequalities using a light-matter interfaced system. By separately benchmarking the Markovian character of the evolution and the translational invariance of the conditional probabilities, the observed violation of a LGtI is attributed to the quantum coherent character of the process. These results provide a general method to benchmark `quantumness' when the absence of memory effects can be independently certified and confirm the persistence of quantum coherent features within systems of increasing complexity.Comment: published version, including supplementary materia

2,10-Dibromo-6-isobutyl-6-methyl­dibenzo[d,f][1,3]dioxepine

In the crystal structure of the title compound, C18H18Br2O2, the two benzene rings of the bridged biphenyl unit are twisted by 38.0 (1)°

A simulated study on the performance of diesel engine with ethanol-diesel blend fuel

This paper describes the simulated study on atomization, wall-film formation, combustion and emission forming process of ethanol-diesel blend fuels in a high speed light duty diesel engine. The result shows that increased ethanol volume percentage of the blend fuels could improve atomization and reduce wall-film formation. However, in the meanwhile, with the increased ethanol volume percentage, low heat values of blend fuels decrease, while both total heat releases and cylinder pressures drop. By adding codes into the FIRE software, the NOx and soot formation region mass fractions are outputted. The simulated results display a good correlation with the NOx and soot formation. Besides, the NOx, soot and CO emissions decrease with the increased ethanol volume percentage. The power output of engine penalize, while energy utilization of blend fuels improve and combustion noise reduce, owing to the increased ethanol volume percentage

3,9-Dibromo-5,7-dihydro­dibenzo[c,e]oxepine

The title compound, C14H10Br2O, is a biphenyl derivative containing a –CH2—O—CH2– bridge in the 2,2′-position. The compound displays a twisted conformation with the two benzene rings making a dihedral angle of 45.02 (5)°, while the central seven-membered ring is in a boat conformation. The mol­ecule lies on a crystallographic twofold axis of symmetry passing through the O atom and bis­ecting the 1,1′ C—C bond

Phase Compensation Enhancement of Photon Pair Entanglement Generated from Biexciton Decays in Quantum Dots

Exciton fine-structure splittings within quantum dots introduce phase differences between the two biexciton decay paths that greatly reduce the entanglement of photon pairs generated via biexciton recombination. We analyze this problem in the frequency domain and propose a practicable method to compensate the phase difference by inserting a spatial light modulator, which substantially improves the entanglement of the photon pairs without any loss.Comment: 4 pages, 3 figure