Quantum information becomes classical when distributed to many users

Any physical transformation that equally distributes quantum information over a large number M of users can be approximated by a classical broadcasting of measurement outcomes. The accuracy of the approximation is at least of the order O(M(-1)). In particular, quantum cloning of pure and mixed states can be approximated via quantum state estimation. As an example, for optimal qubit cloning with 10 output copies, a single user has an error probability p(err) > or = 0.45 in distinguishing classical from quantum output, a value close to the error probability of the random guess.     

Neural network prediction of cycle-to-cycle power variability in a spark-ignited internal combustion engine

Cycle-to-cycle variation (CCV) limits how lean a spark-ignited (SI) internal combustion engine (ICE) can stably operate at, restricts efficiency, and increases emissions through incomplete combustion. Therefore, a way to cleaner, more efficient SI ICEs is to minimize the CCV. Current methods to study CCV include experimental investigations and CFD-based numerical simulations. This study, in contrast, investigates the ability of neural networks to accurately model the indicated mean effective pressure (IMEP) and its coefficient of variation (COV of IMEP). Experimental data from a previous study of spark-ignited propane/air combustion in the TCC-III engine was used to train and evaluate a neural network. An optimized network was generated that utilizes 109 experimental inputs and is operated with 15 neurons in one hidden layer to determine IMEP for 18 engine operating conditions, with 625 individual consecutive engine cycles for each condition. The impact of training set size and the number of input parameters was also investigated. The average deviation for IMEP from the experimental measurements is 0.7–2.2% for the training data set and less than 12% for the entire predicted range of operating conditions. Data sets consisted of tests under rich, lean, and stoichiometric conditions without and with 9% nitrogen dilution. Predicted COV of IMEP strongly correlates with experimental data (R²?=?0.8453). However, a systematic over prediction of COV of IMEP for low COVs was observed while higher COVs were under-predicted by the neural network. The cause for this systematic behavior has not yet been identified but histograms of the predicted IMEP data indicate that this could be related to missing physical parameters that have a significant impact on combustion variability.     

Photochemical and photocatalytic degradation of 1‐propanol using UV/H2O2: Identification of malonate as byproduct

1‐propanol is a primary alcohol extensively used in the pharmaceutical, chemical, and food industries. It has been also found as a contaminant in the atmosphere and is considered a model compound to mimic the behavior and fate of aliphatic alcohols exposed to environmental conditions. In order to understand that role of relevant variables, this paper presents results obtained with a simple experimental set‐up to investigate the reactivity of 1‐propanol under mild oxidizing conditions. Coupling this system with CE‐C⁴D allowed the quantification of the carboxylic acids formed. For the described experiments, aqueous solutions of 1‐propanol were placed inside a photoreactor and oxidized upon the addition of TiO₂ and/or H₂O₂. According to the described results, the addition of H₂O₂ (0.1% w/w) was the most significant variable, roughly tripled the amount of carboxylic acids generated and led to the conversion of up to 70% of the initially available 1‐propanol (1 mmol/L). More importantly, the reaction yielded the formation (within 10 min) of propionate (50 µmol/L), acetate (400 µmol/L), formate (50 µmol/L), and malonate (200 µmol/L). The latter is critically important because it represents the first example of the photochemical oxidation of both terminal carbons of the C₃‐chain of 1‐propanol under mild conditions, and opens new avenues for the production of this important chemical building block.     

Diastereoselective sulfonate-directed carbonyl reduction of γ-keto-sulfonates

The diastereoselective reduction of γ-keto-sulfonates to afford α,γ-substituted γ-hydroxy sulfonates has been investigated. Herein we report the first example of a diastereoselective carbonyl reduction whereby hydride attack is directed via chelation of a neighbouring sulfonate group to a boron atom, thus affording prevalently trans γ-hydroxy sulfonates.     

NMR investigation of degradation processes of ancient and modern paper at different hydration levels

The degradation process of cellulose-made materials was investigated by means of nuclear magnetic resonance (NMR) spectroscopy, with particular emphasis on the role of water and on the hydration mechanism of cellulose fibrils. To accomplish this, the structure and dynamics of water within ancient and modern samples with different aging histories were investigated. The results mainly indicated that hydrolytic and oxidative reactions provoked the formation of acidic by-products. Furthermore, degradation processes were enhanced by higher amounts of water giving a progressive consumption of the amorphous regions of the cellulose. We propose NMR experiments as a benchmark for characterization of the degradation state of paper, as well as for investigating the effectiveness of restoration treatments.     

Diode-pumped Yb3+:KYF4 femtosecond laser

Passive mode locking of a diode-pumped Yb(3+):KYF(4) laser is demonstrated using a semiconductor saturable absorber mirror. A high-stability, transform-limited pulse train with a repetition rate of 57 MHz is generated. Solitonlike pulses with maximum average output power of 250 mW, minimum pulse duration of 170 fs, and rms time jitter of 360 fs were obtained.     

Top-hat cw-laser-induced time-resolved mode-mismatched thermal lens spectroscopy for quantitative analysis of low-absorption materials

Thermal lens spectroscopy is a highly sensitive and versatile photothermal technique for material analysis, providing optical and thermal properties. To use less expensive multimode non-Gaussian lasers for quantitative analysis of low-absorption materials, this Letter presents a theoretical model for time-resolved mode-mismatched thermal lens spectroscopy induced by a cw laser with a top-hat profile. The temperature profile in a sample was calculated, and the intensity of the probe beam center at the detector plane was also derived using the Fresnel diffraction theory. Experimental validation was performed with glass samples, and the results were found well consistent with literature values of the thermo-optical properties of the samples.     

Angular dependence of the thermal-lens effect on LiSrAlF6 and LiSrGaF6 single crystals

We apply thermal-lens (TL) spectrometry to measure the angular dependence of the TL effect on colquiriite single crystals. The experiments were performed with LiSrAlF(6) and LiSrGaF(6) using a two-beam mode-mismatched configuration. The results show that it is possible to minimize the TL effect by selecting the appropriate crystal orientation. Our data also show that the anisotropy of the linear thermal expansion coefficient drives the amplitude of the TL effect, including the inversion from focusing to defocusing as the crystal orientation angle tends to the c-axis direction. The results may be useful for those working to develop a high-power laser using LiSrAlF(6)(:Cr) and LiSrGaF(6)(:Cr) single crystals, allowing for optimization of the designed laser cavity.     

Dissociation of water molecule at three-fold oxygen coordinated V site on the InVO4 (0 0 1) surface

Water molecule adsorption properties at the surface of InVO₄ have been investigated using an ab initio molecular dynamics approach. It was found that the water molecules were adsorbed dissociatively to the three-fold oxygen coordinated V sites on the (0 0 1) surface. The dissociative adsorption energy was estimated to be 0.8-0.9 eV per molecule. The equilibrium distance between V and O of the hydroxyl -OH was almost the same as the V-O distance of tetrahedra VO₄ in the InVO₄ bulk crystal (1.7-1.8 Å).     

Inversion of configuration of alcohols through nucleophilic displacement promoted by nitrate ions.

Inversion of configuration of hydroxy functionalities in biologically significant structures has been performed under mild conditions through nucleophilic displacement by nitrate ion.