Quantum imaging with incoherent photons

We propose a technique to obtain subwavelength resolution in quantum imaging with potentially 100% contrast using incoherent light. Our method requires neither path-entangled number states nor multiphoton absorption. The scheme makes use of N photons spontaneously emitted by N atoms and registered by N detectors. It is shown that for coincident detection at particular detector positions a resolution of lambda/N can be achieved.     

Dirac equation and quantum relativistic effects in a single trapped ion

We present a method of simulating the Dirac equation in 3+1 dimensions for a free spin-1/2 particle in a single trapped ion. The Dirac bispinor is represented by four ionic internal states, and position and momentum of the Dirac particle are associated with the respective ionic variables. We show also how to simulate the simplified 1+1 case, requiring the manipulation of only two internal levels and one motional degree of freedom. Moreover, we study relevant quantum-relativistic effects, like the Zitterbewegung and Klein's paradox, the transition from massless to massive fermions, and the relativistic and nonrelativistic limits, via the tuning of controllable experimental parameters.     

Generation of symmetric Dicke states of remote qubits with linear optics

We propose a method for generating all symmetric Dicke states, either in the long-lived internal levels of N massive particles or in the polarization degrees of freedom of photonic qubits, using linear optical tools only. By means of a suitable multiphoton detection technique, erasing Welcher-Weg information, our proposed scheme allows the generation and measurement of an important class of entangled multiqubit states.     

Diferrocenophosphaborin: A Planar‐Chiral,Redox‐Active and Anion‐Responsive Ambiphilic Ligand

A new class of Janus‐like ambiphilic ligands is introduced. The rigid diferrocene backbone in heterocycles 4‐SnP and 4‐BP creates an unprecedented chiral environment as demonstrated by multinuclear NMR and single‐crystal X‐ray studies. In addition, the ligands are redox‐responsive and the Lewis acidic borane moiety in 4‐BP can be exploited to further tune the properties: a clear decrease in the CO stretching frequency of a Vaska‐type Rh^I complex 5‐BP is observed upon addition of fluoride ions. Thus, the Lewis acid and Lewis base sites influence each other and their strength can be modulated by redox chemistry and anion binding.     

Facile syntheses of novel benzo-1,3-dioxolo-, benzothiazolo-, pyrido-, and quinolino-fused 5H-benzo[d]-pyrazolo[5,1-b][1,3]-oxazines and 1H-pyrazoles

A number of novel benzo-1,3-dioxolo-, benzothiazolo-, pyrido-, and quinolino-fused 5H-benzo[d]pyrazolo[5,1-b][1,3]-oxazines and 1H-pyrazoles were synthesized utilizing an easy and effective N,N-bond forming heterocyclization reaction. In so doing, the substrate scope of this heterocyclization reaction, which starts with o-nitroheterocyclic aldehydes, was expanded to provide several unique heterocyclic compounds for biological screening. This work further demonstrates the versatility of this simple, base-mediated, one-pot heterocyclization method in the construction of novel heterocycles.     

Aero-thermal investigation of a multi-splitter axial turbine

This paper reports the external convective heat transfer in an innovative low-pressure vane, designed with a multi-splitter configuration. Three aerodynamic airfoils are positioned in between larger structural vanes, replacing struts presently used in current aero-engines, which results in superior aerodynamic performance. Static pressure and heat flux measurements were carried out in the large compression tube facility of the von Karman Institute, using pneumatic taps and single-layered thin film gauges respectively. The steady and unsteady heat transfer distributions were obtained at representative conditions of modern aero-engines, with M_2,is close to unity and a Reynolds number of approximately 10⁶. This facility is specially suited to control the gas-to-wall temperature ratio that drives transition mechanisms. The heat transfer across the multi-splittered passages is confronted with correlations on ducts to further characterize the boundary layer status. The data will be used to guide code developers by verifying their boundary layer transition models, and designers by showing the areas of the vane where heat transfer is most sensitive to the off-design conditions.     

Etude cinetique de l'hydrolyse du paranitrophenylphosphate dans l'acetonitrile faiblement aqueux. Processus dissociatif.

Basic hydrolysis of paranitrophenylphosphate in acetonitrile of low water content (0.02 to 0.5 M) is an unimolecular process, with likely a phosphenium cation as intermediate. Comparison with reaction in water - also occuring through an unimolecular process - indicates that the large rate enhancement in CH₃ CN (3.10⁶ for [H₂O] 0.02 M) is entropy controlled.     

Expeditious access to the most easily ionized closed-shell molecule, W2(hpp)4

A new synthetic path, far superior to either of those previously available, to the W2(hpp)4 molecule (Hhpp = 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine) is reported. The reaction of W(CO)6 with Hhpp in o-dichlorobenzene at 200 degrees C produces W2(hpp)4Cl2 in a one-pot reaction in over 90% yield. This compound is stable and easily stored for further use, and it can be efficiently reduced in a one-step reaction to the title compound W2(hpp)4.     

Relativity and lorentz invariance of entanglement distillability

We study entanglement distillability of bipartite mixed spin states under Wigner rotations induced by Lorentz transformations. We define weak and strong criteria for relativistic isoentangled and isodistillable states to characterize relative and invariant behavior of entanglement and distillability. We exemplify these criteria in the context of Werner states, where fully analytical methods can be achieved and all relevant cases presented.     

Dynamic equilibrium between cyclic oligomers. Thermodynamic and structural characterization of a square and a triangle

A dynamic equilibrium has been found in CDCl3 between a neutral molecular square, [cis-Mo2(DAniF)2]4(O2CC6F4CO2)4 (1) and triangle, [cis-Mo2(DAniF)2]3(O2CC6F4CO2)3 (2) (DAniF = the anion of N,N'-di-p-anisylformamidine). The two components have been crystallographically characterized and solution studies by 1H and 19F NMR spectra of the concentration- and the temperature-dependence of the equilibrium have been performed. The conversion of three moles of molecular squares 1 to four moles of molecular triangles 2 has an equilibrium constant of 1.98(7) x 10(-4) at 23.7 degrees C. At this temperature, the DeltaG(0) for the conversion of three moles of squares to four moles of triangles is 21.0 kJ mol(-1). The conversion is enthalpically disfavored (DeltaH(0) = 23.5 kJ mol(-1)), but entropically favored (DeltaS(0) = 8.2 J K(-1) mol(-1)).