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Spin-Based Quantum Information Processing in Magnetic Quantum Dots
2005
We define the qubit as a pair of singlet and triplet states of two electrons in a He-type quantum dot (QD) placed in a diluted magnetic semiconductor (DMS) medium. The molecular field is here essential as it removes the degeneracy of the triplet state and strongly enhances the Zeeman splitting. Methods of qubit rotation as well as two-qubit operations are suggested. The system of a QD in a DMS is described in a way which allows an analysis of the decoherence due to spin waves in the DMS subsystem.
Electron Fabry-Perot interferometer with two entangled magnetic impurities
2007
We consider a one-dimensional (1D) wire along which single conduction electrons can propagate in the presence of two spin-1/2 magnetic impurities. The electron may be scattered by each impurity via a contact-exchange interaction and thus a spin-flip generally occurs at each scattering event. Adopting a quantum waveguide theory approach, we derive the stationary states of the system at all orders in the electron-impurity exchange coupling constant. This allows us to investigate electron transmission for arbitrary initial states of the two impurity spins. We show that for suitable electron wave vectors, the triplet and singlet maximally entangled spin states of the impurities can respectively…
A many-body approach to transport in quantum systems : From the transient regime to the stationary state
2022
We review one of the most versatile theoretical approaches to the study of time-dependent correlated quantum transport in nano-systems: the non-equilibrium Green's function (NEGF) formalism. Within this formalism, one can treat, on the same footing, inter-particle interactions, external drives and/or perturbations, and coupling to baths with a (piece-wise) continuum set of degrees of freedom. After a historical overview on the theory of transport in quantum systems, we present a modern introduction of the NEGF approach to quantum transport. We discuss the inclusion of inter-particle interactions using diagrammatic techniques, and the use of the so-called embedding and inbedding techniques w…
Recent applications of point process methods in forestry statistics
2000
Forestry statistics is an important field of applied statistics with a long tradition. Many forestry problems can be solved by means of point processes or marked point processes. There, the "points" are tree locations and the "marks" are tree characteristics such as diameter at breast height or degree of damage by environmental factors. Point pro- cess characteristics are valuable tools for exploratory data analysis in forestry, for describing the variability of forest stands and for under- standing and quantifying ecological relationships. Models of point pro- cesses are also an important basis of modern single-tree modeling, that gives simulation tools for the investigation of forest stru…
Preferential azido bridging regulating the structural aspects in cobalt(III) and copper(II)–Schiff base complexes: Syntheses, magnetostructural corre…
2011
International audience; A tridentate NNO donor Schiff base ligand [(1Z,3E)-3-((pyridin-2-yl)methylimino)-1-phenylbut-1-en-1-ol = LH] in presence of azide ions coordinates with cobalt(II) and copper(II) ions giving rise to three new coordination complexes [Co2(L)2(μ1,1-N3)2(N3)2] (1), [Cu2(L)2(μ1,3-N3)]·ClO4 (2) and [(μ1,1-N3)2Cu5(μ-OL)2(μ1,1-N3)4(μ1,1,1-N3)2]n (3). The complexes have been characterized by elemental analysis, FT-IR, UV–Vis spectral studies, and single crystal X-ray diffraction studies. These complexes demonstrate that under different synthetic conditions the azide ions and the Schiff base ligand (LH) show different coordination modes with cobalt(II) and copper(II) ions, givi…
Synthesis and structural, spectroscopic and magnetic characterization of iron(II) and iron(III) complexes of N-2-pyridinylcarbonyl-2-pyridinecarboxim…
1993
Abstract One iron(II) complex of N -2-pyridinylcarbonyl-2-pyridinecarboximidate monoanion (bpca), [Fe(bpca) 2 ]·H 2 O ( 1 ), and three iron(III) complexes, [Fe(bpca)Cl 2 (H 2 O)]·(CH 3 ) 2 CO ( 2 ), [Fe(bpca) 2 ](NO 3 )·1.67H 2 O ( 3 ), [Fe(bpca) 2 ](ClO 4 ) ( 4 ), have been prepared and characterized by means of IR, UV-Vis and EPR spectroscopy and magnetic susceptibility measurements, where appropriate. The crystal structures of 1 – 3 have been determined from single crystal X-ray data, showing that the metallic ions are surrounded in all cases by distorted octahedral coordination spheres. From magnetic measurements it is evident that compounds 1 and 3 are practically in the low-spin state…
Mono-, di- and tri-nuclear Ni(II) complexes of N-, O-donor ligands: structural diversity and reactivity
2002
A series of mono-, di- and tri-nuclear Ni(II) complexes of N, O-donating molecules possessing ---H2C---NH--- and ---HC=N--- moieties have been synthesized and characterized and the structures have been determined by single crystal X-ray diffraction. All these exhibited interesting molecular packing in their crystal lattices. Di-nuclear complexes were found to be cleaved in pyridine to result in mononuclear ones with additional coordinations being provided by pyridine. Di-nuclear complexes were found to form urea adducts as demonstrated based on absorption and vibrational studies.
Über antimon-haltige heterocyclen
1980
Abstract p -Nitrophenyl- and p -tolyl-oxadithia- and trithiastibocanes have been synthesized from the respective aryldichlorostibane and dithiole. The compounds have been characterised by means of 13 C NMR and vibrational spectra (ν(SBS 2 ) 350–320 cm −1 ). The crystal structure of p -nitrophenyltrithiastibocane has been determined ( R = 0.042). The eight-membered ring exhibits a boat-chair conformation. Single-bond distances of SbC and SbS (219, 244 and 245 pm), a 1,5-transannular Sb⋯S interaction (319 pm), and Sb⋯S and Sb⋯O (339 and 353 pm) intermolecular contacts, result in a six-coordinated Sb III (ψ-monocapped octahedral) species. The two additional Sb⋯S distances are in accordance w…
Synthesis, crystal structure and magnetic properties of two alternating double μ1,1 and μ1,3 azido bridged Cu(ii) and Ni(ii) chains
2014
Two new alternating μ1,1- and μ1,3-azido bridged chains, [Cu(N3)2(mtn)]n (1) and [Ni(N3)2(mtn)]n (2) where mtn = N-methyl-1,3-propanediamine, have been synthesized and characterized by single crystal X-ray diffraction. In both complexes, each metal atom is coordinated to six nitrogen atoms from four azide anions and one N-methyl-1,3-propanediamine molecule in a distorted octahedral geometry. In 1, the basal-apical double μ1,1-azido bridged Cu(ii)-dimers are connected through two asymmetric μ1,3-N3 bridges to form a 1D chain in which one of the azide acts as a μ1,1,3 bridge while the other one is terminal. The structure of 2 is very similar but one of the azide ions acts as μ1,1 and the othe…
ChemInform Abstract: UEBER ARSEN-HALTIGE HETEROCYCLEN 3. MITT. KRISTALLSTRUKTUR VON 2,6-DIMETHYL-4,4-DIPHENYL-1,4-OXOARSENANIUMBROMID-MONOHYDRAT
1975
Abstract The crystal structure of the title compound has been determined from single crystal X-ray data and refined to a conventional R factor of 0.046. The coordination of the As atom is tetrahedral with a mean As—C distance of 1.92 A. The six-membered heterocycle has chair conformation with two equatorial methyl and one equatorial and one axial phenyl substituent. The transannular 1,4-As⋯O distance is 3.11 A, interactions are discussed. The connection of the structure is more van der Waals than ionic type. Some unspecific gaps are statistically occupied by one molecule of crystal water.