Fast quantum logic gates with trapped-ion qubits.

Quantum bits (qubits) based on individual trapped atomic ions are a promising technology for building a quantum computer. The elementary operations necessary to do so have been achieved with the required precision for some error-correction schemes. However, the essential two-qubit logic gate that is used to generate quantum entanglement has hitherto always been performed in an adiabatic regime (in which the gate is slow compared with the characteristic motional frequencies of the ions in the trap), resulting in logic speeds of the order of 10 kilohertz. There have been numerous proposals of methods for performing gates faster than this natural 'speed limit' of the trap. Here we implement one such method, which uses amplitude-shaped laser pulses to drive the motion of the ions along trajectories designed so that the gate operation is insensitive to the optical phase of the pulses. This enables fast (megahertz-rate) quantum logic that is robust to fluctuations in the optical phase, which would otherwise be an important source of experimental error. We demonstrate entanglement generation for gate times as short as 480 nanoseconds-less than a single oscillation period of an ion in the trap and eight orders of magnitude shorter than the memory coherence time measured in similar calcium-43 hyperfine qubits. The power of the method is most evident at intermediate timescales, at which it yields a gate error more than ten times lower than can be attained using conventional techniques; for example, we achieve a 1.6-microsecond-duration gate with a fidelity of 99.8 per cent. Faster and higher-fidelity gates are possible at the cost of greater laser intensity. The method requires only a single amplitude-shaped pulse and one pair of beams derived from a continuous-wave laser. It offers the prospect of combining the unrivalled coherence properties, operation fidelities and optical connectivity of trapped-ion qubits with the submicrosecond logic speeds that are usually associated with solid-state devices.

Ultrasonic assisted synthesis of RGO supported HoVO4-ZnO nanocomposites, their enhanced photocatalytic activities and Rhodamine B degradation.

The RGO-supported HoVO4-ZnO nanocomposite was synthesized using the ultra sonication process. X-ray diffraction patterns, Field emission scanning electron microscopy, high resolution transmission electron microscopy, Diffractive Reflectance spectroscopy, and photoluminescence spectroscopy were employed to examine the heterostructured photocatalyst in this research study. The photocatalytic efficiency of the RGO-supported HoVO4-ZnO nanoparticles, under UV light irradiation, in the degradation of Rhodamine-B dye was investigated. Undoped ZnO, bare HoVO4, and HoVO4 -ZnO, degraded at 55.6, 57.5, and 74.33 percent in 45 min, respectively. This new RGO coupled HoVO4-ZnO exhibits enhanced photocatalytic efficiency compared to the bare ZnO and HoVO4-ZnO nanocomposite.

Benchmarking a High-Fidelity Mixed-Species Entangling Gate.

We implement a two-qubit logic gate between a ^{43}Ca^{+} hyperfine qubit and a ^{88}Sr^{+} Zeeman qubit. For this pair of ion species, the S-P optical transitions are close enough that a single laser of wavelength 402 nm can be used to drive the gate but sufficiently well separated to give good spectral isolation and low photon scattering errors. We characterize the gate by full randomized benchmarking, gate set tomography, and Bell state analysis. The latter method gives a fidelity of 99.8(1)%, comparable to that of the best same-species gates and consistent with known sources of error.

High-Rate, High-Fidelity Entanglement of Qubits Across an Elementary Quantum Network.

We demonstrate remote entanglement of trapped-ion qubits via a quantum-optical fiber link with fidelity and rate approaching those of local operations. Two ^{88}Sr^{+} qubits are entangled via the polarization degree of freedom of two spontaneously emitted 422 nm photons which are coupled by high-numerical-aperture lenses into single-mode optical fibers and interfere on a beam splitter. A novel geometry allows high-efficiency photon collection while maintaining unit fidelity for ion-photon entanglement. We generate heralded Bell pairs with fidelity 94% at an average rate 182 s^{-1} (success probability 2.18×10^{-4}).

UV-A Light Driven Activated Charcoal Supported Bi2O3-ZnO Nanocomposites; Hydrothermal Synthesis and Their Enhanced Photocatalytic and Self Cleaning Applications.

The Activated Charcoal supported Bi2O3-ZnO (AC-BZ) nanocomposite is successfully synthesized by simple and efficient hydrothermal followed by thermal decomposition method. The addition of Activated charcoal into the Bi2O3-ZnO matrices increases the active sites and shows efficient catalytic activity upon the degradation of azo dyes, Rhodamine-B (Rh-B) and Trypan Blue (TB). Prepared photocatalysts further prove its ability by the way of structure and absorption capacity. For understanding the efficiency of photocatalyst, it was characterized by X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Field Emission Transmission Electron Microscopy (FE-TEM), High Resolution Transmission Electron Microscopy (HR-TEM), Diffused Reflectance Spectroscopy (UV-DRS), Photo Luminescense spectroscopy (PL) and N2 adsorption- desorption isotherms (BET). The FESEM images of the activated charcoal supported Bi2O3-ZnO show a nanocomposite structure and reveal that most of particles have hexagonal and spherical type in nano range. Absorption range and band gap energy were examined by UV-DRS techniques, which indicate the photogenerated electrons and holes are responsible for better photocatalytic activity. The prepared AC-BZ nanocomposite has maximum efficiency at pH 7, and it shows enhanced degradation efficiency up to four cycles which proves reusability of the catalyst. The obtained catalyst shows higher efficiency in self cleaning property by forming maximum degree of contact angle when compared with pure ZnO and Bi2O3-ZnO. This work may provide new strategy for eco-friendly and cost effective photocatalysts for various applications.

Fabrication of an effectual, stable and reusable Mg-doped CdAl2O4 nanoparticles for photodegradation of toxic pollutants under visible light illumination.

The water contamination caused by discharging extensive organic dyes stuff into water bodies is one of the utmost significant concerns disturbing the environment and human life. CdAl2O4 spinel materials have been excellent in the elimination of emerging pollutants by the photocatalysis route. These materials, when altered through methods namely doping with Mg ions, have benefits over CdAl2O4, especially reduced energy gap and light absorbed in the visible region. The XRD established the creation of space group R 3‾ with no other phase step being found. The photoluminescence outcomes indicated that Mg-doped CdAl2O4 nanoparticles had the preventing e--h+ recombination possibility, which was favorable for the photocatalytic process. The Mg (0.075 M)-doped CdAl2O4 catalyst had higher photocatalytic performance with 94 and 96% removal of two azo (BB and BG) dyes under a mere 90 min visible light irradiation, which indicated enhanced Photodegradation behaviors when compared to other Mg (0.025, 0.050 M)-doped and pure CdAl2O4 materials. More interestingly, pH 5 was optimum for the Mg (0.075 M)-doped CdAl2O4 samples photodegradation of both dyes, and the optimum catalyst amount was 5 mg/100 mL. The doped Mg ions influenced the elimination of both dyes by inducing the manufacture of more active species. The Mg (0.075 M)-doped CdAl2O4 samples is reusable and highly stable with only a 5% reduction in degradation rate after six cycles. Based on the quencher and ESR investigations, the .OH- and h+ are described as active species in the removal reaction. We hope our present examinations highlight the possibility of using Mg (0.075 M)-doped CdAl2O4 product for a broad range of photodegradation applications, also it may be applied for several ecological remediations, surface cleaning devices, foods and pharmaceutical industry applications.

Strategies for ameliorating the photodegradation efficiency of Mn-doped CdAl2O4 nanoparticles for the toxic dyes under visible light illumination.

Worldwide environmental issues have been escalating with the growth of the global economy and become a vital problem. To solve the problems, we require an eco-friendly and sustainable binary catalyst for the degradation of Azo dye pollutants. In this work, magnetically reusable, multifunctional novel Mn-doped CdAl2O4 nanoparticles were effectively fabricated by the co-precipitation approach. It was utilized for the degradation of two Azo dyes, exhibiting 96 and 98% Mn (0.050 M)-doped CdAl2O4 removal rates under visible light illumination, and presenting improved photocatalytic capability than that of pure and other dopants. More notably, the Mn (0.050 M)-doped CdAl2O4 catalyst was recycled using centrifuges without major loss and displays almost similar photodegradation behaviors for six successive runs. According to the ESR measurements, outcome and quenching tests affirmed that .OH- and h+ radicals were better reactive species responsible for Azo dyes removal. A possible photodegradation reaction mechanism underlying the elimination of Azo dyes by Mn (0.050 M)-doped CdAl2O4 catalyst is also proposed. Elaborated analyzes by variable reaction parameters such as the role of reactive species and catalyst dosage, pH, COD and irradiation time in the degradation route was also discussed. We assume that our outcomes will provide novel insights into using a highly effectual Mn (0.050 M)-doped CdAl2O4 catalyst, with possible applications in the treatment of both industrial and domestic wastewater.

Preparation and characterization of a novel cobalt-substitution cadmium aluminate spinel for the photodegradation of azo dye pollutants.

Modern-year organic contaminants have been highly observed in ecosystems since they are not removed entirely and remain dangerous. Semiconductor binary oxide photocatalysts have been well accredited as capable technology for ecological contaminants degradation in the existence of visible irradiation. In this research, novel Co ions doped CdAl2O4 materials were fabricated by a facile co-precipitation approach. The fabricated pure and Co-doped CdAl2O4 exhibited the typical peaks of CdAl2O4 with the Eg of 3.66, 3.24, 2.57, and 2.41 eV respectively. The HR-TEM microstructures revealed that the Co (0.075 M) doped CdAl2O4 has rod-like morphology, and some places are spherical with particle sizes reaching 21 nm. The PL peaks of the Co (0.075 M)-CdAl2O4 are much lesser than that of the other dopant and pure CdAl2O4, representing much more effectual separation of generated e- and h+ at the interface which in fact outcomes in superior expected photodegradation behaviours. The Co (0.075 M)-CdAl2O4 catalyst demonstrated the highest performances of 92 and 94% toward the degradation of both dyes, respectively, owing to the lowest e- and h+ recombination rate. The Co (0.075 M) doped CdAl2O4 photocatalyst revealed outstanding reusability and stability under visible irradiation, retaining the performance of about 83 and 86% after the fifth consecutive run of BB and BG elimination. A probable photodegradation mechanism of Co (0.075 M) doped CdAl2O4 was suggested since the photoexcited h+, OH- and O2- species contributed to the removal process, and that was affirmed by the scavenging test and ESR analysis. This research offers new ways to improve the photodegradation performance of the Co-doped CdAl2O4 catalyst that will be employed in pharmaceutical applications and wastewater treatment.

A synergistic consequence of catalyst dosage, pH solution and reactive species of Fe-doped CdAl2O4 nanoparticles on the degradation of toxic environmental pollutants.

Industrial wastewater treatment techniques are one of the biggest challenges of the scientific community that necessitate an increased consciousness to address water scarcity worldwide. Herein, an eco-friendly and cost-effective process was demonstrated to cope with tannery, textile and pharmaceutical dye wastes through the co-precipitation of highly reusable Fe-doped CdAl2O4 samples. The XRD studies exposed the space group R 3‾ with no secondary phase step being found for all samples. The outcomes of optical absorbance spectra demonstrate that Fe doping diminished the energy gap from 3.66 to 1.67 eV. HR-TEM images of existing spherical particles and some of the particles' rod-like structures with little agglomeration were found for Fe (0.075 M) doped CdAl2O4 nanoparticles. The PL emission outcomes show that Fe doping effectively prevented the charge carrier's recombination in CdAl2O4 during photocatalysis. All Fe-doped CdAl2O4 samples demonstrated higher photodegradation behaviors towards the effectual degradation of both dye solutions as compared to pure CdAl2O4 samples. Particularly, Fe (0.075 M)-doped CdAl2O4 samples exhibited improved photodegradation performance of 93 and 95% for both dye solutions. The amount of photodegradation was noticed to rely on dye pH, irradiation time, catalyst dosage, initial dye amount, and reactive species. The recyclability of the Fe (0.075 M) doped CdAl2O4 nanoparticles denotes that 78 and 82% of BB and BG were removed up to the 6th run of usage. The outcomes of trapping tests,.OH- and h+ radicals were the major Scavenging in the photodegradation reaction. COD studies affirmed the whole mineralization of BB and BG dye molecules. It is expected that our present examination could offer to improve various spinal oxide materials for the photodegradation activity of pharmaceutical contaminants and environmental issues and can also resolve energy storage applications.

Novel Ag-TiO2/ZnFe2O4 Nanocomposites for Effective Photocatalytic, Electrocatalytic and Cytotoxicity Applications.

We report the preparation and characterization of a new heterostructured Ag-TiO2/ZnFe2O4 (ATZ) nanocomposite. X-ray diffraction (XRD) reveals the presence of spinel type ZnFe2O4 and anatase TiO2. Scanning electron microscope (SEM) images of ATZ nanocomposites show that Ag nanoparticles are successfully loaded on the composite Ag-TiO2 and is uniformly distributed on surface of ZnFe2O4 forming a nanocomposite with an approximate particle size of 44.8 nm. High-resolution transmission electron microscope (HR-TEM) analysis clearly indicates the particles with spherical and hexagonal structure and sizes of most of the particles are below 50 nm. Ultra violet-visible diffuse reflectance spectra (UV-vis-DRS) show that Ag-TiO2/ZnFe2O4 has increased visible absorption than TiO2. Photoluminescence (PL) spectra shows that the intensity of ATZ is low relative to prepared TiO2. The photocatalytic degradation of Reactive Yellow 86 (RY 86) dye was studied. Based on the band gap energies of TiO2 and ZnFe2O4, a mechanism of degradation is given. Photocatalytic activity results suggest that as-prepared ATZ shows higher photodegradation efficiency than pure TiO2. The main reactive oxidative species involved in the degradation and stability of photocatalyst were also investigated. ATZ shows higher electrocatalytic activity than TiO2 for methanol electrooxidation. The cytotoxicity of ATZ was analysed. Multifunctionality of ATZ makes it useful for environmental and biomedical applications.

One-Pot Synthesis of Tetra Substituted Imidazoles Catalyzed by Fly Ash Supported Bi2O3-ZnO.

A simple and efficient one pot synthesis of 1,2,4,5-tetra substituted imidazoles is achieved by condensation-cyclization reaction of benzil, aromatic aldehyde, 2-amino ethyl pyrrolidine, ammonium acetate using fly ash loaded Bi2O3-ZnO. Different substituted aldehydes have been used in this reaction. The process is operationally simple, environmentally safe and has magnificent yield. Furthermore this catalyst can be recycled at least four times without any loss of activity.

Magnetic field stabilization system for atomic physics experiments.

Atomic physics experiments commonly use millitesla-scale magnetic fields to provide a quantization axis. As atomic transition frequencies depend on the magnitude of this field, many experiments require a stable absolute field. Most setups use electromagnets, which require a power supply stability not usually met by commercially available units. We demonstrate the stabilization of a field of 14.6 mT to 4.3 nT rms noise (0.29 ppm), compared to noise of >100 nT without any stabilization. The rms noise is measured using a field-dependent hyperfine transition in a single 43Ca+ ion held in a Paul trap at the center of the magnetic field coils. For the 43Ca+ "atomic clock" qubit transition at 14.6 mT, which depends on the field only in second order, this would yield a projected coherence time of many hours. Our system consists of a feedback loop and a feedforward circuit that control the current through the field coils and could easily be adapted to other field amplitudes, making it suitable for other applications such as neutral atom traps.

IpaB, a Shigella flexneri invasin, colocalizes with interleukin-1 beta-converting enzyme in the cytoplasm of macrophages.

Shigellae are the most prevalent etiological agents of dysentery. A crucial step in shigella pathogenesis is the induction of macrophage apoptosis. The invasion plasmid antigen B (IpaB) is necessary and sufficient to induce macrophage programmed cell death. IpaB activates apoptosis by binding to interleukin-1 beta (IL-1 beta)-converting enzyme (ICE) or a highly homologous protease. Here, we show that IpaB is disseminated throughout the cytoplasm of shigella-infected macrophages as detected by both immunofluorescence and immunoelectron microscopy. The cytoplasmic distribution of IpaB requires phagosome escape, and it is specific to IpaB, since lipopolysaccharide, used here as a bacterial marker, remains closely associated with the bacteria. In double-labeling experiments, we show that IpaB and ICE colocalize in the cytoplasm of the macrophage, suggesting that soon after secretion, IpaB binds to ICE to initiate apoptosis and to promote the cleavage of IL-1 beta.

The interleukin 1beta-converting enzyme, caspase 1, is activated during Shigella flexneri-induced apoptosis in human monocyte-derived macrophages.

Shigella, the etiological agent of bacillary dysentery, rapidly kills human monocyte-derived macrophages in vitro. Wild-type Shigella flexneri, but not a nonvirulent derivative, induced human macrophage apoptosis as determined by morphology and terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL). Shigella-mediated macrophage cell death was blocked by the peptide inhibitors of caspases, acetyl-Tyr-Val-Ala-Asp-aldehyde (acetyl-YVAD-CHO) and acetyl-Tyr-Val-Ala-Asp-chloromethylketone (acetyl-YVAD-CMK). Protection from apoptosis by YVAD was observed in monocytes matured in the presence or absence of colony-stimulating factors (CSF) like macrophage-CSF or granulocyte-macrophage-CSF. Furthermore, lipopolysaccharide (LPS) or gamma interferon (IFN-gamma) rendered human macrophages partially resistant to Shigella cytotoxicity. Macrophages stimulated with either LPS or IFN-gamma were also protected by YVAD from Shigella-induced cell death. During Shigella infections of human macrophages, interleukin-1beta (IL-1beta) was cleaved to the mature form. IL-1beta maturation was severely retarded by YVAD, indicating that IL-1beta-converting enzyme (ICE; caspase 1) is activated in Shigella-induced apoptosis. The finding that Shigella induces apoptosis in human macrophages by activating ICE supports the hypothesis that the acute inflammation characteristic of shigellosis is initially triggered by apoptotic macrophages which release mature IL-1beta during programmed cell death.

A bacterial invasin induces macrophage apoptosis by binding directly to ICE.

Shigella, the etiological agent of dysentery, kills macrophages by inducing apoptosis. Deletion mutants in the invasion invasion plasmid antigen B (ipaB) of Shigella flexneri are not cytotoxic. Here, we localized IpaB to the cytoplasm of macrophages infected with S. flexneri. Purified IpaB induced apoptosis when microinjected into macrophages, indicating that IpaB is sufficient to induce apoptosis. Using a GST-IpaB fusion protein as a ligand in affinity purification, we isolated four IpaB binding proteins from macrophages which were identified as the precursor and the mature polypeptides of interleukin-1beta converting enzyme (ICE) or a highly homologous protease. We found that IpaB binds directly to ICE and this enzyme is activated during S. flexneri infection. Furthermore, specific inhibitors of ICE prevented Shigella-induced apoptosis.

In vivo apoptosis in Shigella flexneri infections.

Shigella flexneri, an etiological agent of bacillary dysentery, causes apoptosis in vitro. Here we show that it also induces apoptosis in vivo. We were able to quantify the number of apoptotic cells in rabbit Peyer's patches infected with S. flexneri by detecting cells with fragmented DNA. Infection with virulent S. flexneri results in massive numbers of apoptotic cells within the lymphoid follicles. In contrast, neither an avirulent strain nor an avirulent strain capable of colonizing Peyer's patches increases the background level of apoptotic cells. Macrophages, T cells, and B cells are shown to undergo apoptosis in vivo. These results indicate that apoptosis may play a crucial role in the pathogenesis of shigellosis.

Caspase-1 activation of IL-1beta and IL-18 are essential for Shigella flexneri-induced inflammation.

Caspases are intracellular proteases that mediate mammalian cell apoptosis. Caspase-1 (Casp-1) is a unique caspase because it activates the proinflammatory cytokines interleukin (IL)-1beta and IL-18. Shigella flexneri, the etiological agent of bacillary dysentery, induces macrophage apoptosis, which requires Casp-1 and results in the release of mature IL-1beta and IL-18. Here we show that casp-1(-/-) mice infected with S. flexneri do not develop the acute inflammation characteristic of shigellosis and are unable to resolve the bacterial infection. Using casp-1(-/-) mice supplemented with recombinant cytokines and experiments with IL-1beta(-/-) and IL-18(-/-) mice, we show that IL-1beta and IL-18 are both required to mediate inflammation in S. flexneri infections. Together, these data demonstrate the importance of Casp-1 in acute inflammation and show the different roles of its substrates, IL-1beta and IL-18, in this response.