No quantum advantage for nonlocal computation

We investigate the problem of "nonlocal" computation, in which separated parties must compute a function with nonlocally encoded inputs and output, such that each party individually learns nothing, yet together they compute the correct function output. We show that the best that can be done classically is a trivial linear approximation. Surprisingly, we also show that quantum entanglement provides no advantage over the classical case. On the other hand, generalized (i.e. super-quantum) nonlocal correlations allow perfect nonlocal computation. This gives new insights into the nature of quantum nonlocality and its relationship to generalised nonlocal correlations.Comment: 4 page

Hetero-Diels–Alder reactions of hetaryl and aryl thioketones with acetylenic dienophiles

Selected hetaryl and aryl thioketones react with acetylenecarboxylates under thermal conditions in the presence of LiClO4 or, alternatively, under high-pressure conditions (5 kbar) at room temperature yielding thiopyran derivatives. The hetero-Diels–Alder reaction occurs in a chemo- and regioselective manner. The initially formed [4 + 2] cycloadducts rearrange via a 1,3-hydrogen shift sequence to give the final products. The latter were smoothly oxidized by treatment with mCPBA to the corresponding sulfones.The authors thank the National Science Center (Cracow, Poland) for generous financial support (Grant Maestro-3 (Dec- 2012/06/A/ST5/00219). Skilful performance of microanalyses by Ms Hanna Jatczak and Ms Agnieszka Cieślińska (University of Łódź) is gratefully acknowledge

Pre- and post-selected quantum states: density matrices, tomography, and Kraus operators

We present a general formalism for charecterizing 2-time quantum states, describing pre- and post-selected quantum systems. The most general 2-time state is characterized by a `density vector' that is independent of measurements performed between the preparation and post-selection. We provide a method for performing tomography of an unknown 2-time density vector. This procedure, which cannot be implemented by weak or projective measurements, brings new insight to the fundamental role played by Kraus operators in quantum measurements. Finally, after showing that general states and measurements are isomorphic, we show that any measurement on a 2-time state can be mapped to a measurement on a preselected bipartite state.Comment: 7 page

The disentangling power of unitaries

We define the disentangling power of a unitary operator in a similar way as the entangling power defined by Zanardi et al. [P. Zanardi, C. Zalka, L. Faoro, Phys. Rev. A 62 (2000) 030301(R), quant-ph/0005031]. A general formula is derived and it is shown that both quantities are directly proportional. All results concerning the entangling power can simply be translated into similar statements for the disentangling power. In particular, the disentangling power is maximal for certain permutations derived from orthogonal Latin squares. These permutations can therefore be interpreted as those that distort entanglement in a maximal way

Equilibration of quantum systems and subsystems

We unify two recent results concerning equilibration in quantum theory. We first generalise a proof of Reimann [PRL 101,190403 (2008)], that the expectation value of 'realistic' quantum observables will equilibrate under very general conditions, and discuss its implications for the equilibration of quantum systems. We then use this to re-derive an independent result of Linden et. al. [PRE 79, 061103 (2009)], showing that small subsystems generically evolve to an approximately static equilibrium state. Finally, we consider subspaces in which all initial states effectively equilibrate to the same state.Comment: 5 page

Identity in research infrastructure and scientific communication: Report from the 1st IRISC workshop, Helsinki Sep 12-13, 2011

Motivation for the IRISC workshop came from the observation that identity and digital identification are increasingly important factors in modern scientific research, especially with the now near-ubiquitous use of the Internet as a global medium for dissemination and debate of scientific knowledge and data, and as a platform for scientific collaborations and large-scale e-science activities.

The 1 1/2 day IRISC2011 workshop sought to explore a series of interrelated topics under two main themes: i) unambiguously identifying authors/creators & attributing their scholarly works, and ii) individual identification and access management in the context of identity federations. Specific aims of the workshop included:

• Raising overall awareness of key technical and non-technical challenges, opportunities and developments.
• Facilitating a dialogue, cross-pollination of ideas, collaboration and coordination between diverse – and largely unconnected – communities.
• Identifying & discussing existing/emerging technologies, best practices and requirements for researcher identification.

This report provides background information on key identification-related concepts & projects, describes workshop proceedings and summarizes key workshop findings

cis-(6RS,13RS)-3,3,10,10-Tetramethyl-6,13-diphenyl-1,8-dioxa-4,11-diazacyclotetradecane-2,5,9,12-tetraone and two of its precursors

The title macrocycle, C26H30N2O6, (VI), was obtained by ;direct amide cyclization' from the linear precursor 3-hydroxy-N-[1-methyl-1-(N-methyl-N-phenylcarbamoyl)ethyl]-2-phenylpropanamide, the N-methylanilide of rac-2-methyl-2-[(3-hydroxy-2-phenylpropanoyl)amino]propanoic acid, C13H17NO4, (IV). The reaction proceeds via the intermediate rac-2-(2-hydroxy-1-phenylethyl)-4,4-dimethyl-1,3-oxazol-5(4H)-one, C13H15NO3, (V), which was synthesized independently and whose structure was also established. Unlike all previously described analogues, the title macrocycle has the cis-diphenyl configuration. The 14-membered ring has a distorted rectangular diamond-based [3434] configuration and intermolecular N-H...O hydrogen bonds link the molecules into a three-dimensional framework. The propanoic acid precursor forms a complex series of intermolecular hydrogen bonds, each of which involves pairwise association of molecules and which together result in the formation of extended two-dimensional sheets. The oxazole intermediate forms centrosymmetric hydrogen-bonded dimers in the solid state

Directional Ionic Bonds

Covalent and ionic bonds represent two fundamental forms of bonding between atoms. In contrast to bonds with significant covalent character, ionic bonds are of limited use for the spatial structuring of matter because of the lack of directionality of the electric field around simple ions. We describe a predictable directional orientation of ionic bonds that contain concave nonpolar shields around the charged sites. Such directional ionic bonds offer an alternative to hydrogen bonds and other directional noncovalent interactions for the structuring of organic molecules and materials

Synthesis of Z-Protected Aib- and Phe(2Me)-Containing Pentapeptides and Their Crystal Structures

A series of pentapeptide derivatives containing alpha,alpha-disubstituted alpha-amino acids have been prepared by a combination of the 'azirine/oxazolone method' and segment condensations. X-Ray crystal-structure determinations of the molecular structures confirmed the presence of helical conformations stabilized by beta-turns of type III or III’. Pentapeptides containing (R)-Phe(2Me) form a right-handed helix, whereas those containing (S)-Phe(2Me) adopt a left-handed helical structure

Thermolysis of imidates: A new method for the generation of carbonyl ylides

Thermolysis of dimethyl 2-[(3-oxo-3H-isoindol-1-yl)oxy]malonate (8) promotes a [1,4]-H shift in the imidic N¼C O CH fragment of the starting molecule, which leads to a reactive carbonyl ylide. This carbonyl ylide can be trapped by the C¼N bond of imidates and imines, as well as the C¼O bond of benzaldehyde. The corresponding cycloadducts 11, 14, and 16 are formed regioselectively in good yields (60 – 95%) and with high stereoselectivity. In the case of 11, the minor cycloadduct in solution undergoes an isomerization to give the more stable stereoisomer. The structures of two cycloadducts, i.e., 11a and 14a, have been established by X-ray crystallography