Disorder effects on the quantum coherence of a many-boson system

The effects of disorders on the quantum coherence for many-bosons are studied in a double well model. For the ground state, the disorder enhances the quantum coherence. In the deep Mott regime, dynamical evolution reveals periodical collapses and revivals of the quantum coherence which is robust against the disorder. The average over variations in both the on-site energy and the interaction reveals a beat phenomenon of the coherence-decoherence oscillation in the temporal evolution.Comment: 4 figure

Persistent Ballistic Entanglement Spreading with Optimal Control in Quantum Spin Chains

Entanglement propagation provides a key routine to understand quantum many-body dynamics in and out of equilibrium. In this work, we uncover that the ``variational entanglement-enhancing'' field (VEEF) robustly induces a persistent ballistic spreading of entanglement in quantum spin chains. The VEEF is time dependent, and is optimally controlled to maximize the bipartite entanglement entropy (EE) of the final state. Such a linear growth persists till the EE reaches the genuine saturation $\tilde{S} = - \log_{2} 2^{-\frac{N}{2}}=\frac{N}{2}$ with $N$ the total number of spins. The EE satisfies $S(t) = v t$ for the time $t \leq \frac{N}{2v}$, with $v$ the velocity. These results are in sharp contrast with the behaviors without VEEF, where the EE generally approaches a sub-saturation known as the Page value $\tilde{S}_{P} =\tilde{S} - \frac{1}{2\ln{2}}$ in the long-time limit, and the entanglement growth deviates from being linear before the Page value is reached. The dependence between the velocity and interactions is explored, with $v \simeq 2.76$, $4.98$, and $5.75$ for the spin chains with Ising, XY, and Heisenberg interactions, respectively. We further show that the nonlinear growth of EE emerges with the presence of long-range interactions.Comment: 5 pages, 4 figure

Penta­aqua­(1H-benzimidazole-5,6-dicarboxyl­ato-κN 3)nickel(II) penta­hydrate

In the title mononuclear complex, [Ni(C9H4N2O4)(H2O)5]·5H2O, the NiII atom is six-coordinated by one N atom from a 1H-benzimidazole-5,6-dicarboxyl­ate ligand and by five O atoms from five water mol­ecules and displays a distorted octa­hedral geometry. Inter­molecular O—H⋯O hydrogen-bonding inter­actions among the coordinated water mol­ecules, solvent water mol­ecules and carboxyl O atoms of the organic ligand and additional N—H⋯O hydrogen bonding lead to the formation of a three-dimensional supra­molecular network

Diaqua­bis­(4-carb­oxy-2-propyl-1H-imidazole-5-carboxyl­ato-κ2 N 3,O 4)cobalt(II) N,N-dimethyl­formamide disolvate

In the title complex, [Co(C8H9N2O4)2(H2O)2]·2C3H7NO, the CoII cation (site symmetry ) is six-coordinated by two 5-carb­oxy-2-propyl-1H-imidazole-4-carboxyl­ate ligands and two water mol­ecules in a distorted octa­hedral environment. In the crystal structure, the complex mol­ecules and dimethyl­formamide solvent mol­ecules are linked by extensive O—H⋯O and N—H⋯O hydrogen bonding into sheets lying parallel to (21)

Hexaaqua­nickel(II) 4,4′-(1,2-dihy­droxy­ethane-1,2-di­yl)dibenzoate monohydrate

In the title compound, [Ni(H2O)6](C16H12O6)·H2O, the NiII cation is located on a mirror plane and is coordinated by six water mol­ecules, two of which are also located on the mirror plane, in a distorted octa­hedral geometry. The 4,4′-(1,2-dihy­droxy­ethane-1,2-di­yl)dibenzoate anion is centrosymmetric with the mid-point of the central ethane C—C bond located on an inversion center. The uncoordinated water mol­ecule is located on a mirror plane. Extensive O—H⋯O hydrogen bonding is present in the crystal structure