Information-Theoretic Measure of Genuine Multi-Qubit Entanglement

We consider pure quantum states of N qubits and study the genuine N-qubit entanglement that is shared among all the N qubits. We introduce an information-theoretic measure of genuine N-qubit entanglement based on bipartite partitions. When N is an even number, this measure is presented in a simple formula, which depends only on the purities of the partially reduced density matrices. It can be easily computed theoretically and measured experimentally. When N is an odd number, the measure can also be obtained in principle.Comment: 5 pages, 2 figure

4-Butyl­anilinium perchlorate

In the crystal structure of the title salt, C10H16N+·ClO4 −, the 4-butyl­anilinium cation is mirror symmetric, the butyl C atoms and anilinium N atom and 1,4-position C atoms of the benzene ring being located on the mirror plane; the perchlorate anion is also mirror symmetric, with two O atoms and one Cl atom lying on the mirror plane. Trifurcated N—H⋯O hydrogen bonding is observed between the cation and anion in the crystal structure

5-(1H-Tetra­zol-5-yl)-1H-indole monohydrate

In the title compound, C9H7N5·H2O, the inter­planar angles between the benzene and tetra­zole rings and between the benzene and imidazole rings are 8.71 (3) and 1.32 (2)°, respectively. In the crystal, strong N—H⋯N hydrogen bonds link the organic 5-(1H-tetra­zol-5-yl)-1H-indole mol­ecules into chains extended along the b axis. The chains are further inter­connected into layers parallel to (100) via strong O—H⋯N and N—H⋯O hydrogen bonds. Furthermore, the layers are inter­connected via strong O—H⋯N hydrogen bonds. Moreover, cohesion between the layers is provided by the π–π inter­actions between the imidazole, tetra­zole and benzene rings with centroid–centroid distances of 3.766 (2), 3.832 (2) and 3.733 (2) Å