Ultra-thin 2-bit anisotropic Huygens coding metasurface for terahertz wave manipulation.

In this work, we design an ultrathin 2-bit anisotropic Huygens coding metasurface (AHCM) composed by bilayer metallic square-ring structures for flexible manipulation of the terahertz wave. Based on the polarized-dependent components of electric surface admittance and magnetic surface impedance, we confirm that both the electric and magnetic resonances on coding meta-atoms are excited, so as to provide a full phase coverage and significantly low reflection. By encoding the elements with distinct coding sequences, the x- and y-polarized incident waves are anomalously refracted into opposite directions. More uniquely, we also demonstrate that the designed AHCM can be utilized as a transmission-type quarter-wave plate. The proposed metasurface paves a new way toward multifunctional terahertz wavefront manipulation.

Discrimination of enantiomers through quantum interference and quantum Zeno effect.

Quantum optical methods have great potential for highly efficient discrimination of chiral molecules. We propose quantum interference-based schemes of enantio-discrimination under microwave regime among molecular rotational states. The quantum interference between field-driven one- and two-photon transitions of two higher states is designed to be constructive for one enantiomer but destructive for the other, since a certain transition dipole moment can be set to change sign with enantiomers. Therefore, two enantiomers can evolve into entirely different states from the same ground state. Through strengthening the constructive interference, the quantum Zeno effect is found in one enantiomer and then its excitation is suppressed, which also enables the enantio-discrimination. We simulate the schemes for differentiating between S and R enantiomers of 1, 2-propanediol (C3H8O2) molecules. With the analysis of the phase sensitivity to microwave fields and the effect of energy relaxations, the highly efficient enantio-discrimination of the 1, 2-propanediol molecules may be achieved.

Multi-qubit phase gate on multiple resonators mediated by a superconducting bus.

We propose a one-step scheme for implementing multi-qubit phase gates on microwave photons in multiple resonators mediated by a superconducting bus in circuit quantum electrodynamics (QED) system. In the scheme, multiple single-mode resonators carry quantum information with their vacuum and single-photon Fock states, and a multi-level artificial atom acts as a quantum bus which induces the indirect interaction among resonators. The method of pulse engineering is used to shape the coupling strength between resonators and the bus so as to improve the fidelity and robustness of the scheme. We also discuss the influence of finite coherence time for the bus and resonators on gate fidelity respectively. Finally, we consider the suppression of unwanted transitions and propose the method of optimized detuning compensation for offsetting unwanted transitions, showing the feasibility of the scheme within the current experiment technology.

Effective Rabi dynamics of Rydberg atoms and robust high-fidelity quantum gates with a resonant amplitude-modulation field.

With a resonant amplitude-modulation field on two Rydberg atoms, we propose a Rydberg antiblockade (RAB) regime, where the Rabi oscillation between collective ground and excited states is induced. A controlled-Z gate can be yielded through a Rabi cycle. Further, several common issues of the RAB gates are solved by modifying the parameter relation. The gate fidelity and gate robustness against the control error are enhanced with a shaped pulse. The requirement of control precision of the Rydberg-Rydberg interaction strength is relaxed. In addition, the atomic excitation is restrained and therefore the gate robustness against atomic decay is enhanced.

Construction of robust Rydberg controlled-phase gates.

One scheme is presented to construct the robust multi-qubit arbitrary-phase controlled-phase gate (CPG) with one control and multiple target qubits in Rydberg atoms using the Lewis-Riesenfeld (LR) invariant method. The scheme is not limited by adiabatic condition while preserves the robustness against control parameter variations of adiabatic evolution. Comparing with the adiabatic case, our scheme does not require very strong Rydberg interaction strength. Taking the construction of two-qubit π CPG as an example, our scheme is more robust against control parameter variations than non-adiabatic scheme and faster than adiabatic scheme.

Shortcut to adiabatic passage in a three-level system via a chosen path and its application in a complicated system.

We construct a shortcut to an adiabatic passage in a three-level system by choosing a dressed state acting as an evolutive path. Two designed auxiliary pulses are added into the original pulses to eliminate the couplings between the chosen evolutive-path state and the other two dressed states. The same target state as one gotten by adiabatic passage can be rapidly obtained, and the population of the lossy intermediate state can be controlled by setting proper parameters. Furthermore, as an example, we use this method in the adiabatic-passage scheme [Opt. Express20, 014547 (2012)], a complicated cavity quantum electrodynamics system, to successfully accelerate the generation of the three-dimensional entanglement between a single atom and a Bose-Einstein condensate.

MicroRNA-374a protects against myocardial ischemia-reperfusion injury in mice by targeting the MAPK6 pathway.

AIMS: Clinical treatment strategies for patients with myocardial ischemia typically include coronary artery recanalization to restore myocardial blood supply. However, myocardial reperfusion insult often induces oxidative stress and inflammation, which further leads to apoptosis and necrosis of myocardial cells. Increasing evidence suggests that microRNAs (miRNAs) participate in the pathological and physiological processes associated with myocardial ischemia reperfusion. MAIN METHODS: In this study, we established a myocardial H/R H9C2 cell model and a mouse I/R model to detect molecules implicated in myocardial I/R regulation and to determine the underlying signal transduction pathways. KEY FINDINGS: Herein, we showed that the expression of miR-374a-5p decreased in a myocardial cell model (H9C2 cells) of hypoxia/reoxygenation (H/R) and mouse model of ischemia/reperfusion (I/R). Alternatively, overexpression of miR-374a-5p was found to ameliorate myocardial cell damage within both in vivo and in vitro models of ischemia. Further, mitogen-activated protein kinase 6 (MAPK6) was identified as a direct target of miR-374a-5p. Thus, by targeting MAPK6, miR-374a-5p was found to negatively regulate MAPK6 expression. However, up-regulation of MAPK6 functioned to inhibit the previously observed protective effect of miR-374a-5p in the H9C2 H/R model. SIGNIFICANCE: Taken together, our study suggests that miR-374a-5p may have protective effects against cardiac I/R injury in vivo, and H/R injury in vitro, thereby providing novel insights into the molecular mechanisms associated with ischemia/reperfusion injury and a potential novel therapeutic target.

Fast adiabatic quantum state transfer and entanglement generation between two atoms via dressed states.

We propose a dressed-state scheme to achieve shortcuts to adiabaticity in atom-cavity quantum electrodynamics for speeding up adiabatic two-atom quantum state transfer and maximum entanglement generation. Compared with stimulated Raman adiabatic passage, the dressed-state scheme greatly shortens the operation time in a non-adiabatic way. By means of some numerical simulations, we determine the parameters which can guarantee the feasibility and efficiency both in theory and experiment. Besides, numerical simulations also show the scheme is robust against the variations in the parameters, atomic spontaneous emissions and the photon leakages from the cavity.

Fast generations of tree-type three-dimensional entanglement via Lewis-Riesenfeld invariants and transitionless quantum driving.

Recently, a novel three-dimensional entangled state called tree-type entanglement, which is likely to have applications for improving quantum communication security, was prepared via adiabatic passage by Song et al. Here we propose two schemes for fast generating tree-type three-dimensional entanglement among three spatially separated atoms via shortcuts to adiabatic passage. With the help of quantum Zeno dynamics, two kinds of different but equivalent methods, Lewis-Riesenfeld invariants and transitionless quantum driving, are applied to construct shortcuts to adiabatic passage. The comparisons between the two methods are discussed. The strict numerical simulations show that the tree-type three-dimensional entangled states can be fast prepared with quite high fidelities and the two schemes are both robust against the variations in the parameters, atomic spontaneous emissions and the cavity-fiber photon leakages.

One-step synthesis of highly monodisperse hybrid silica spheres in aqueous solution.

An effective and reproducible method of preparing highly monodisperse organic-inorganic hybrid silica spheres was studied. One process, one precursor (organosilane) and one solvent (water) were used in our experiments. The size of hybrid silica spheres could be adjusted from 360 to 770 nm with relative standard deviation below 2% by controlling the concentration of the organosilane precursor and the ammonia catalyst. The increasing of the precursor concentration increases the particle size while the catalyst concentration has a reverse effect on the particle size. The concept of homogeneous nucleation and growth processes are introduced to explain the formation mechanism and the effect of reaction conditions. The scanning electron microscopy (SEM) images illustrate the copiousness in quantity and the uniformity in size/shape of the particles that could be routinely accomplished in this synthesis. Fourier transform infrared (FT-IR) and (29)Si nuclear magnetic resonance (NMR) spectra confirm the structure of vinyl hybrid silica spheres, where the vinyl group (-CH=CH(2)) exists and connects to the silicon atom. This method has also been extended to design and prepare other organic-inorganic hybrid materials especially in monodisperse surface-modified silica spheres.

Koopmans' theorem for large molecular systems within density functional theory.

It is shown that in density functional theory (DFT), Koopmans' theorem for a large molecular system can be stated as follows: The ionization energy of the system equals the negative of the highest occupied molecular orbital (HOMO) energy plus the Coulomb electrostatic energy of removing an electron from the system, or equivalently, the ionization energy of an N-electron system is the negative of the arithmetic average of the HOMO energy of this system and the lowest unoccupied molecular orbital (LUMO) energy of the (N - 1)-electron system. Relations between this DFT Koopmans' theorem and its existing counterparts in the literature are discussed. Some of the previous results are generalized and some are simplified. DFT calculation results of a fullerene molecule, a finite single-walled carbon nanotube and a finite boron nitride nanotube are presented, indicating that this Koopmans' theorem approximately holds, even if the orbital relaxation is taken into consideration.

Near homogeneous variation of potentials in large systems and the electronic structure of molecular quantum dots.

It is shown from Kohn-Sham (KS) density-functional theory that in a large molecular system, the Coulomb potential, molecular electrostatic potential, and KS effective potential may exhibit an approximately homogeneous variation in space, in response to a small change of the electron number. The homogeneous variation of potentials underlies the constant interaction (CI) model of quantum dots (QDs) and is related to the delocalization and invariance of KS orbitals, the identical shift of KS levels, and a natural definition of the QD capacitance. Calculation results of a fullerene C60 and a single-walled carbon nanotube are presented. Although the homogeneity of the potential variation is not perfect, it seems to lead to fairly good approximation of the CI model to the addition energy spectra of these systems.