Quantum-classical transition for an analog of double-slit experiment in complex collisions: Dynamical decoherence in quantum many-body systems

We study coherent superpositions of clockwise and anti-clockwise rotating intermediate complexes with overlapping resonances formed in bimolecular chemical reactions. Disintegration of such complexes represents an analog of famous double-slit experiment. The time for disappearance of the interference fringes is estimated from heuristic arguments related to fingerprints of chaotic dynamics of a classical counterpart of the coherently rotating complex. Validity of this estimate is confirmed numerically for the H+D$_2$ chemical reaction. Thus we demonstrate the quantum--classical transition in temporal behavior of highly excited quantum many-body systems in the absence of external noise and coupling to an environment.Comment: 5 pages, 2 ps color figures. Accepted for publication in Phys. Rev.

Gamma-ray burst contributions to constraining the evolution of dark energy

We explore the gamma-ray bursts' (GRBs') contributions in constraining the dark energy equation of state (EOS) at high ($1.8 < z < 7$) and at middle redshifts ($0.5 < z < 1.8$) and estimate how many GRBs are needed to get substantial constraints at high redshifts. We estimate the constraints with mock GRBs and mock type Ia supernovae (SNe Ia) for comparisons. When constraining the dark energy EOS in a certain redshift range, we allow the dark energy EOS parameter to vary only in that redshift bin and fix EOS parameters elsewhere to -1. We find that it is difficult to constrain the dark energy EOS beyond the redshifts of SNe Ia with GRBs unless some new luminosity relations for GRBs with smaller scatters are discovered. However, at middle redshifts, GRBs have comparable contributions with SNe Ia in constraining the dark energy EOS.Comment: 3 pages, 5 figures. Published in Astronomy and Astrophysics. Corrected referenc

Evolution of Magnetism in Single-Crystal Honeycomb Iridates

We report the successful synthesis of single-crystals of the layered iridate, (Na$_{1-x}$Li$_{x}$)$_2$IrO$_3$, $0\leq x \leq 0.9$, and a thorough study of its structural, magnetic, thermal and transport properties. The new compound allows a controlled interpolation between Na$_2$IrO$_3$ and Li$_2$IrO$_3$, while maintaing the novel quantum magnetism of the honeycomb Ir$^{4+}$ planes. The measured phase diagram demonstrates a dramatic suppression of the N\'eel temperature, $T_N$, at intermediate $x$ suggesting that the magnetic order in Na$_2$IrO$_3$ and Li$_2$IrO$_3$ are distinct, and that at $x\approx 0.7$, the compound is close to a magnetically disordered phase that has been sought after in Na$_2$IrO$_3$ and Li$_2$IrO$_3$. By analyzing our magnetic data with a simple theoretical model we also show that the trigonal splitting, on the Ir$^{4+}$ ions changes sign from Na$_2$IrO$_3$ and Li$_2$IrO$_3$, and the honeycomb iridates are in the strong spin-orbit coupling regime, controlled by \jeff=1/2 moments.Comment: updated version with more dat

Análisis de volátiles mediante GC-MS de aceites esenciales de canela extraídos por diferentes métodos

Cinnamon essential oil (CEO) was extracted by three different methods: steam distillation (SD), ultrasound-assisted steam distillation (UASD) and microwave-assisted steam distillation (MASD). The volatiles in CEO were separated and identified by gas chromatography–mass spectrometry (GC-MS), and the differences in volatiles among the three different methods were further analyzed through principal component analysis. The results showed that 36 individual volatile components were present in the CEO from the three different methods. In general, the numbers of aldehydes, esters, alcohols, terpenes, aromatics and ketones were 6, 3, 7, 17, 2, and 1, respectively. The most abundant volatile component was determined to be cinnamic aldehyde. The content of total cinnamic aldehydes, which determines the price of CEO, was the highest among the three methods in the UASD sample (85.633%). Moreover, the highest yield (8.33‰) of essential oil was extracted by the UASD method. Therefore, UASD was the best way for CEO extraction in this research and was recommended for future industrial applications.El aceite esencial de canela (AEC) se extrajo mediante tres métodos diferentes: destilación al vapor (DV), destilación al vapor asistida por ultrasonido (DVAU) y destilación al vapor asistida por microondas (DVAM). Los volátiles del AEC se separaron e identificaron mediante cromatografía de gases-espectrometría de masas (GC-MS), las diferencias de los volátiles entre los tres métodos se analizaron adicionalmente a través del análisis de componentes principales. Los resultados mostraron la presencia de 36 componentes volátiles en el AEC mediante los tres métodos diferentes. En general, el número de aldehídos, ésteres, alcoholes, terpenos, aromáticos y cetonas presentes fue de 6, 3, 7, 17, 2 y 1, respectivamente. Se determinó que el componente volátil más abundante era el aldehído cinámico. El contenido de aldehído cinámico total, el cual decide el precio del AEC, en la muestra de DVAU (85,633%), fue el más alto entre tres métodos. Además, el mayor rendimiento (8,33‰) de aceite esencial se encontró mediante el método DVAU. Por lo tanto, DVAU fue la mejor forma de extracción de AEC en esta investigación y se recomienda en futuras aplicaciones industriales