Comparing Geometric Discord and Negativity for Bipartite States

The geometric discord $\mathcal{D}$ of a state is a measure of the quantumness of the state and the negativity $\mathcal{N}$ is a measure of the entanglement of a state. It was proved by D. Girolami and G. Adesso that for states on $\mathbb{C}^2\otimes\mathbb{C}^2$, the geometric discord is always greater than or equal to the square of the negativity and conjectured that this holds in general. S. Rana and P. Parashar showed that this relation does not hold for all states on $\mathbb{C}^2\otimes\mathbb{C}^n$ for $n>2$. We provide several analytic families of states on $\mathbb{C}^2\otimes\mathbb{C}^3$ violating this relation. Certain upper and lower bounds for $\mathcal{N}^2-\mathcal{D}$ are obtained for states on $\mathbb{C}^m\otimes\mathbb{C}^n$ for any $m, n\in\mathbb{N}$.Comment: Bounds for the difference of the square of the negativity and the geometric discord are improved. 9 pages, 4 figure

Aerosol-Jet-Assisted Thin-Film Growth of CH3NH3PbI3 Perovskites—A Means to Achieve High Quality, Defect-Free Films for Efficient Solar Cells

AbstractA high level of automation is desirable to facilitate the lab‐to‐fab process transfer of the emerging perovskite‐based solar technology. Here, an automated aerosol‐jet printing technique is introduced for precisely controlling the thin‐film perovskite growth in a planar heterojunction p–i–n solar cell device structure. The roles of some of the user defined parameters from a computer‐aided design file are studied for the reproducible fabrication of pure CH3NH3PbI3 thin films under near ambient conditions. Preliminary power conversion efficiencies up to 15.4% are achieved when such films are incorporated in a poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate‐perovskite‐phenyl‐C71‐butyric acid methyl ester type device format. It is further shown that the deposition of atomized materials in the form of a gaseous mist helps to form a highly uniform and PbI2 residue‐free CH3NH3PbI3 film and offers advantages over the conventional two‐step solution approach by avoiding the detrimental solid–liquid interface induced perovskite crystallization. Ultimately, by integrating full 3D motion control, the fabrication of perovskite layers directly on a 3D curved surface becomes possible. This work suggests that 3D automation with aerosol‐jet printing, once fully optimized, could form a universal platform for the lab‐to‐fab process transfer of solution‐based perovskite photovoltaics and steer development of new design strategies for numerous embedded structural power applications

On Numerical Radius of a Matrix and Estimation of Bounds for Zeros of a Polynomial

We obtain inequalities involving numerical radius of a matrix A∈Mn(ℂ). Using this result, we find upper bounds for zeros of a given polynomial. We also give a method to estimate the spectral radius of a given matrix A∈Mn(ℂ) up to the desired degree of accuracy