Shanghai University

About: Shanghai University is a education organization based out in Shanghai, Shanghai, China. It is known for research contribution in the topics: Microstructure & Graphene. The organization has 59583 authors who have published 56840 publications receiving 753549 citations. The organization is also known as: Shànghǎi Dàxué.

Optimally robust shortcuts to population inversion in two-level quantum systems

Abstract: We examine the stability versus different types of perturbations of recently proposed shortcuts to adiabaticity to speed up the population inversion of a two-level quantum system. We find the optimally robust processes by using invariant-based engineering of the Hamiltonian. Amplitude noise and systematic errors require different optimal protocols.

Stability analysis for solitons in PT-symmetric optical lattices

Abstract: Stability of solitons in parity-time (PT)-symmetric periodic potentials (optical lattices) is analyzed in both one- and two-dimensional systems First we show analytically that when the strength of the gain-loss component in the PT lattice rises above a certain threshold (phase transition point), an infinite number of linear Bloch bands turn complex simultaneously Second, we show that while stable families of solitons can exist in PT lattices, increasing the gain-loss component has an overall destabilizing effect on soliton propagation Specifically, when the gain-loss component increases, the parameter range of stable solitons shrinks as new regions of instability appear Third, we investigate the nonlinear evolution of unstable PT solitons under perturbations, and show that the energy of perturbed solitons can grow unbounded even though the PT lattice is below the phase transition point

Atomically dispersed metal catalysts for the oxygen reduction reaction: synthesis, characterization, reaction mechanisms and electrochemical energy applications

Abstract: In recent years, atomically dispersed metal catalysts (ADMCs) with well-defined structures have attracted great interest from researchers for electrocatalytic applications due to their maximum atom utilization efficiency (100%), distinct active sites and high catalytic activity, stability and selectivity. Based on this, this review will comprehensively discuss the recent developments in advanced single-atom and dual-atom ADMCs for the oxygen reduction reaction (ORR), including synthesis and characterization, reaction mechanisms and energy applications such as in fuel cells and metal–air batteries. In addition, challenges will be summarized and analyzed, including the rational design and fabrication of ADMCs and a deeper understanding of their geometric configuration, electronic structure and reaction dynamics towards the ORR. Furthermore, to facilitate further development, future research directions are proposed to overcome associated challenges, such as (1) the exploration of new/advanced materials including metal precursors and supporting substrates for the fabrication of ADMCs; (2) the optimization of rational design and synthesis techniques for single- and dual-atom catalysts to significantly enhance catalytic ORR activity and stability based on modern characterization techniques; (3) a deeper understanding of ADMC structures, reactive active sites, interactions between metal atoms and support surfaces and corresponding electrocatalytic ORR mechanisms at the atomic level using a combination of density functional theory (DFT) calculations and advanced experimental techniques; (4) the optimization of ADMC-based catalyst layers and membrane electrode assemblies to achieve high performance fuel cells and metal–air batteries using advanced electrochemical testing strategies.