A polymorph of diaqua­bis(pyrazine-2-carboxyl­ato-κ2 N 1,O)copper(II)

The title compound, [Cu(C5H3N2O2)2(H2O)2], is a new polymorph of the previously reported compound [Klein et al. (1982 ▶). Inorg. Chem. 21, 1891–1897]. The CuII atom, lying on an inversion center, is coordinated by two N atoms and two O atoms from two pyrazine-2-carboxyl­ate ligands and by two water mol­ecules in a distorted octa­hedral geometry with the water mol­ecules occupying the axial sites. Inter­molecular O—H⋯O, O—H⋯N and C—H⋯O hydrogen bonds connect the complex mol­ecules into a two-dimensional layer parallel to (10), whereas the previously reported polymorph exhibits a three-dimensional hydrogen-bonded network

catena-Poly[[dichloridozinc(II)]-μ-1,1′-(butane-1,4-di­yl)diimidazole-κ2 N 3:N 3′]

The title compound, [ZnCl2(C10H14N4)]n, is a coordination polymer consisting of zigzag chains propagating in [001], in which the metal cation exhibits a distorted tetrahedral ZnCl2N2 coordination. Adjacent chains are linked by inter­molecular C—H⋯Cl hydrogen bonds, forming a three-dimensional supra­molecular network

Inguinal canal angioleiomyoma: case report of a rare disease entity within inguinal canal

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Secure Key from Quantum Discord

The study of quantum information processing seeks to characterize the resources that enable quantum information processing to perform tasks that are unfeasible or inefficient for classical information processing. Quantum cryptography is one such task, and researchers have identified entanglement as a sufficient resource for secure key generation. However, quantum discord, another type of quantum correlation beyond entanglement, has been found to be necessary for guaranteeing secure communication due to its direct relation to information leakage. Despite this, it is a long-standing problem how to make use of discord to analyze security in a specific quantum cryptography protocol. Here, based on our proposed quantum discord witness recently, we successfully address this issue by considering a BB84-like quantum key distribution protocol and its equivalent entanglement-based version. Our method is robust against imperfections in qubit sources and qubit measurements as well as basis misalignment due to quantum channels, which results in a better key rate than standard BB84 protocol. Those advantages are experimentally demonstrated via photonic phase encoding systems, which shows the practicality of our results