Characterizing nonclassicality and entanglement

In Quantum Optics, the widely accepted definition of nonclassicality is based on the P function of Glauber and Sudarshan. When it fails to be interpreted as a classical probability density, the corresponding quantum state is said to be a nonclassical one. Here we present the first reconstruction of a nonclassical P function of a single-photon added thermal state. We also consider the nonclassical properties of general spacegtime dependent correlation functions of radiation fields. For the detection of these correlation functions, a balanced homodyne correlation technique was proposed. It is shown that the measurable correlation functions also allow one to completely characterize bipartite entangled quantum states with a negative partial transposition. Finally, we present a method for identifying general bipartite entanglement for continuous variables.     

On optimal allocation of risk vectors

In this paper we extend results on optimal risk allocations for portfolios of real risks w.r.t. convex risk functionals to portfolios of risk vectors. In particular we characterize optimal allocations minimizing the total risk as well as Pareto optimal allocations. Optimal risk allocations are shown to exhibit a worst case dependence structure w.r.t. some specific max-correlation risk measure and they are comonotone w.r.t. a common worst case scenario measure. We also derive a new existence criterion for optimal risk allocations and discuss some examples.     

Entanglement persistency of multiphoton entangled states

We experimentally demonstrate the entanglement persistency when losing photons in three- and four-photon polarization-entangled states. The entanglement properties of the mixed states obtained from multiphoton spontaneous parametric down-conversion are studied via witness and positive partial transpose approaches. Together with a quantification of the bipartite entanglement such analysis enables intuitive understanding of novel multiparty quantum communication protocols.     

Promoting the Electrocatalytic Performance of Noble Metal Aerogels by Ligand-Directed Modulation

Noble metal aerogels (NMAs) are an emerging class of porous materials. Embracing nano-sized highly-active noble metals and porous structures, they display unprecedented performance in diverse electrocatalytic processes. However, various impurities, particularly organic ligands, are often involved in the synthesis and remain in the corresponding products, hindering the investigation of the intrinsic electrocatalytic properties of NMAs. Here, starting from laser-generated inorganic-salt-stabilized metal nanoparticles, various impurity-free NMAs (Au, Pd, and Au-Pd aerogels) were fabricated. In this light, we demonstrate not only the intrinsic electrocatalytic properties of NMAs, but also the prominent roles played by ligands in tuning electrocatalysis through modulating the electron density of catalysts. These findings may offer a new dimension to engineer and optimize the electrocatalytic performance for various NMAs and beyond.     

Experimental analysis of a four-qubit photon cluster state

Linear-optics quantum logic operations enabled the observation of a four-photon cluster state. We prove genuine four-partite entanglement and study its persistency, demonstrating remarkable differences from the usual Greenberger-Horne-Zeilinger (GHZ) state. Efficient analysis tools are introduced in the experiment, which will be of great importance in further studies on multiparticle entangled states.     

Strong Laws and Summability for φ-Mixing Sequences of Random Variables

In this note the almost sure convergence of stationary, -mixing sequences of random variables according to summability methods is linked to the fulfillment of a certain integrability condition generalizing and extending the results for i.i.d. sequences. Furthermore we give via Baum-Katz type results an estimate for the rate of convergence in these laws.     

On the construction of hourly price forward curves for electricity prices

Computational Management Science - There are several approaches in the literature for the derivation of price forward curves (PFCs) which distinguish among each other by the procedure employed for...     

Kristall- und Molekülstruktur der solvatfreien Hexamethyldisilazide des Rubidiums und Caesiums und die Kristallstruktur eines Toluolsolvates

Crystal and Molecular Structure of the Solventfree Hexamethyldisilazides of Rubidium and Cesium and the Crystal Structure of a Toluene Solvate X-ray crystal structures are reported for the dimeric rubidium and cesium hexamethyldisilazides [MN(SiMe₃)₂]₂. [RbN(SiMe₃)₂]₂ ( 1 ) crystallizes in the monoclinic space group P2₁/c with a = 1044.7(2), b = 891.1(2), c = 1281.0(3) pm, β = 100.26(2) °, Z = 2. [CsN(SiMe₃)₂]₂ ( 2 ) crystallizes in the orthorhombic space group Pbca with a = 1270.81(2), b = 1281.16(1), c = 1539.65(2) pm, Z = 4. Both compounds contain a four-membered [M–N–]₂-ring located on an inversion centre. The M–N bond lengths are: 287.8(2), 295.6(2) pm ( 1 ) and 307.4(2), 314.9(2) pm ( 2 ). The solvate [CsN(SiMe₃)₂]₂ · C₇H₈ ( 3 ) crystallizes from toluene in the triclinic space group P1 with a = 854.00(2), b = 979.58(2), c = 1084.45(3) pm, α = 111.482(1), β = 93.821(1), γ = 108.546(1)°, Z = 1. In this compound dimeric units [CsN(SiMe₃)₂]₂ and toluene molecules form a polymeric chain.