Exact Solution of the Bose-Hubbard Model with Unidirectional Hopping.

A one-dimensional Bose-Hubbard model with unidirectional hopping is shown to be exactly solvable. Applying the algebraic Bethe ansatz method, we prove the integrability of the model and derive the Bethe ansatz equations. The exact eigenvalue spectrum can be obtained by solving these equations. The distribution of Bethe roots reveals the presence of a superfluid-Mott insulator transition at the ground state, and the critical point is determined. By adjusting the boundary parameter, we demonstrate the existence of a non-Hermitian skin effect even in the presence of interaction, but it is completely suppressed for the Mott insulator state in the thermodynamical limit. Our result represents a new class of exactly solvable non-Hermitian many-body systems, which has no Hermitian correspondence and can be used as a benchmark for various numerical techniques developed for non-Hermitian many-body systems.

Zinc(II)-Quinoline module and ROS cleavable crosslinker functionalized self-fluorescent siRNA vectors for selective gene silencing of cancer cells.

A highly efficient siRNA vector (Zn-PQD) capable of selectively silencing genes in cancer cells was obtained by using ROS-cleavable DED to crosslink low molecular weight (LMW) polyethylene imine (PEI) modified by self-fluorescent metal coordinatied multifunctional module Zn-QS. Under the combined action of DED cross-linking and Zn-QS modification, Zn-PQD performs well in the siRNA delivery process in cancer cells, including siRNA condensation, cell uptake, endosome escape, and siRNA release. Zn-PQD exhibited higher transfection efficiency than commercial PEI25k and Lipo2k in multiple cancer cell lines including HepG2, HeLa, 4 T1, H520 and PANC-1, as well as cancer treatment-related stem cell rADSC. Ultimately, Zn-PQD can achieve extremely high and selective gene silencing effects in cancer cells (with a gene silencing rate of 98.3% in HepG2). This work is expected to provide an efficient and safe siRNA carrier for the future tumor siRNA therapy and its study of fluorescence mediated mechanism.

Tet1 peptide and zinc (II)-adenine multifunctional module functionalized polycations as efficient siRNA carriers for Parkinson's disease.

A bioreducible Zn (II)-adenine multifunctional module (BS) and Tet1 peptide were used to modify low-molecular-weight PEI3.5k (polyethyleneimine with molecular weight of 3.5 kDa)into a siRNA vector Zn-PB-T with high transfection efficiency in neurons. A GSH-responsive breakable disulfide spacer was introduced into BS to realize the controlled release of siRNA from the polyplexes in cytoplasm. Zn-PB showed >90% transfection rates in multiple cell lines (3 T3, HK-2, HepG2, 293 T, HeLa, PANC-1)，and 1.8-folds higher EGFP knockdown rates than commercial Lipo2k in normal cell line 293 T and cancer cell line HepG2. And Zn-PB-T1 showed 4.7-4.9- and 8.0-8.1-folds higher transfection efficiency comparing to commercial Lipo2k and PEI25k (polyethyleneimine with molecular weight of 25 kDa) in PC12 cells respectively, 2.1-fold EGFP gene silencing efficiency (96.6% EGFP knockdown rates) superior to commercial Lipo2k in neurons. In Parkinson's model, Zn-PB-T1/SNCA-siRNA can effectively protect neurons against MPP+-induced cell death and apoptosis, increasing the cell survival rate to 84.6% and reducing the cell apoptosis rate to 10.8%. This work demonstrated the promising application prospects of the resulting efficient siRNA carriers in siRNA-mediated gene therapy of Parkinson's disease.

Expanding the Scope of Polymerization-Induced Self-Assembly: Recent Advances and New Horizons.

Over the past decade or so, polymerization-induced self-assembly (PISA) has become a versatile method for rational preparation of concentrated block copolymer nanoparticles with a diverse set of morphologies. Much of the PISA literature has focused on the preparation of well-defined linear block copolymers by using linear macromolecular chain transfer agents (macro-CTAs) with high chain transfer constants. In this review, a recent process is highlighted from an unusual angle that has expanded the scope of PISA including i) synthesis of block copolymers with nonlinear architectures (e.g., star block copolymer, branched block copolymer) by PISA, ii) in situ synthesis of blends of polymers by PISA, and iii) utilization of macro-CTAs with low chain transfer constants in PISA. By highlighting these important examples, new insights into the research of PISA and future impact these methods will have on polymer and colloid synthesis are provided.

How the Reactive End Group of Macro-RAFT Agent Affects RAFT-Mediated Emulsion Polymerization-Induced Self-Assembly.

Polymerization-induced self-assembly via reversible addition-fragmentation chain transfer (RAFT)-mediated emulsion polymerization is an emerging method in which macro-RAFT agents are chain extended with hydrophobic monomers in water to form block copolymer nano-objects. However, almost all RAFT-mediated emulsion polymerizations are limited to AB diblock copolymers by using monofunctional macro-RAFT agents with non-reactive end groups. In this study, the first investigation on how the reactive end group of macro-RAFT agent affects RAFT-mediated emulsion polymerization is reported. Three macro-RAFT agents with different end groups are synthesized and employed in RAFT-mediated emulsion polymerization. Effects of end groups on morphologies of block copolymer nano-objects and polymerization process are studied. Block copolymer nano-objects prepared by using an asymmetric difunctional macro-RAFT agent can be functionalized by further chain extension on the surface. It is expected that the current study will not only expand the scope of RAFT-mediated emulsion polymerization, but also provide a novel strategy to prepare functional polymer nanoparticles.

Thermoresponsive Block Copolymer Vesicles by Visible Light-Initiated Seeded Polymerization-Induced Self-Assembly for Temperature-Regulated Enzymatic Nanoreactors.

Block copolymer vesicles loaded with active compounds have been employed as decent candidates to mimic complex biological systems that attract considerable interest in different research communities. We herein report a visible light-initiated seeded reversible addition-fragmentation chain transfer (RAFT)-mediated polymerization-induced self-assembly (PISA) for in situ preparation of enzyme-loaded cross-linked block copolymer vesicles without compromising the bioactivity. Permeability of the vesicular membrane can be regulated through changing the solution temperature, allowing further control over the enzymatic reaction rate of enzyme-loaded vesicles. Finally, non-cross-linked thermoresponsive block copolymer vesicles that can transform into worm-like micelles at low temperature are also prepared by this method, allowing the release of bimacromolecules from the vesicles under mild conditions.

Maximal Holevo Quantity Based on Weak Measurements.

The Holevo bound is a keystone in many applications of quantum information theory. We propose " maximal Holevo quantity for weak measurements" as the generalization of the maximal Holevo quantity which is defined by the optimal projective measurements. The scenarios that weak measurements is necessary are that only the weak measurements can be performed because for example the system is macroscopic or that one intentionally tries to do so such that the disturbance on the measured system can be controlled for example in quantum key distribution protocols. We evaluate systematically the maximal Holevo quantity for weak measurements for Bell-diagonal states and find a series of results. Furthermore, we find that weak measurements can be realized by noise and project measurements.

Quantum speed limit for arbitrary initial states.

The minimal time a system needs to evolve from an initial state to its one orthogonal state is defined as the quantum speed limit time, which can be used to characterize the maximal speed of evolution of a quantum system. This is a fundamental question of quantum physics. We investigate the generic bound on the minimal evolution time of the open dynamical quantum system. This quantum speed limit time is applicable to both mixed and pure initial states. We then apply this result to the damped Jaynes-Cummings model and the Ohimc-like dephasing model starting from a general time-evolution state. The bound of this time-dependent state at any point in time can be found. For the damped Jaynes-Cummings model, when the system starts from the excited state, the corresponding bound first decreases and then increases in the Markovian dynamics. While in the non-Markovian regime, the speed limit time shows an interesting periodic oscillatory behavior. For the case of Ohimc-like dephasing model, this bound would be gradually trapped to a fixed value. In addition, the roles of the relativistic effects on the speed limit time for the observer in non-inertial frames are discussed.

Tunable band topology reflected by fractional quantum Hall States in two-dimensional lattices.

Two-dimensional lattice models subjected to an external effective magnetic field can form nontrivial band topologies characterized by nonzero integer band Chern numbers. In this Letter, we investigate such a lattice model originating from the Hofstadter model and demonstrate that the band topology transitions can be realized by simply introducing tunable longer-range hopping. The rich phase diagram of band Chern numbers is obtained for the simple rational flux density and a classification of phases is presented. In the presence of interactions, the existence of fractional quantum Hall states in both |C| = 1 and |C| > 1 bands is confirmed, which can reflect the band topologies in different phases. In contrast, when our model reduces to a one-dimensional lattice, the ground states are crucially different from fractional quantum Hall states. Our results may provide insights into the study of new fractional quantum Hall states and experimental realizations of various topological phases in optical lattices.

Off-diagonal Bethe ansatz and exact solution of a topological spin ring.

A general method is proposed for constructing the Bethe ansatz equations of integrable models without U(1) symmetry. As an example, the exact spectrum of the XXZ spin ring with a Möbius-like topological boundary condition is derived by constructing a modified T-Q relation based on the functional connection between the eigenvalues of the transfer matrix and the quantum determinant of the monodromy matrix. With the exact solution, the elementary excitations of the topological XX spin ring are discussed in detail. It is found that the excitation spectrum indeed shows a nontrivial topological nature.

Fidelity susceptibility in the two-dimensional transverse-field Ising and XXZ models.

We study the fidelity susceptibility in the two-dimensional (2D) transverse-field Ising model and the 2D XXZ model numerically. It is found that in both models, the fidelity susceptibility as a function of the driving parameter diverges at the critical points. The validity of the fidelity susceptibility to signal for the quantum phase transition is thus verified in these two models. We also compare the scaling behavior of the extremum of the fidelity susceptibility to that of the second derivative of the ground-state energy. From those results, the theoretical argument that fidelity susceptibility is a more sensitive seeker for a second-order quantum phase transition is also testified in the two models.