Realizing Synthetic Dimensions and Artificial Magnetic Flux in a Trapped-Ion Quantum Simulator.

Synthetic dimension is a potent tool in quantum simulation of topological phases of matter. Here we propose and demonstrate a scheme to simulate an anisotropic Harper-Hofstadter model with controllable magnetic flux on a two-leg ladder using the spin and motional states of a single trapped ion. We verify the successful simulation of this model by comparing the measured dynamics with theoretical predictions under various coupling strength and magnetic flux, and we observe the chiral motion of wave packets on the ladder as evidence of the topological chiral edge modes. We develop a quench path to adiabatically prepare the ground states for varying magnetic flux and coupling strength, and we measure the chiral current on the ladder for the prepared ground states, which allows us to probe the quantum phase transition between the Meissner phase and the vortex phase. Our work demonstrates the trapped ion as a powerful quantum simulation platform for topological quantum matter.

Observation of Non-Markovian Spin Dynamics in a Jaynes-Cummings-Hubbard Model Using a Trapped-Ion Quantum Simulator.

The Jaynes-Cummings-Hubbard (JCH) model is a fundamental many-body model for light-matter interaction. As a leading platform for quantum simulation, the trapped ion system has realized the JCH model for two to three ions. Here, we report the quantum simulation of the JCH model using up to 32 ions. We verify the simulation results even for large ion numbers by engineering low excitations and thus low effective dimensions; then we extend to 32 excitations for an effective dimension of 2^{77}, which is difficult for classical computers. By regarding the phonon modes as baths, we explore Markovian or non-Markovian spin dynamics in different parameter regimes of the JCH model, similar to quantum emitters in a structured photonic environment. We further examine the dependence of the non-Markovian dynamics on the effective Hilbert space dimension. Our Letter demonstrates the trapped ion system as a powerful quantum simulator for many-body physics and open quantum systems.

Experimental Realization of the Rabi-Hubbard Model with Trapped Ions.

Quantum simulation provides important tools in studying strongly correlated many-body systems with controllable parameters. As a hybrid of two fundamental models in quantum optics and in condensed matter physics, the Rabi-Hubbard model demonstrates rich physics through the competition between local spin-boson interactions and long-range boson hopping. Here, we report an experimental realization of the Rabi-Hubbard model using up to 16 trapped ions and present a controlled study of its equilibrium properties and quantum dynamics. We observe the ground-state quantum phase transition by slowly quenching the coupling strength, and measure the quantum dynamical evolution in various parameter regimes. With the magnetization and the spin-spin correlation as probes, we verify the prediction of the model Hamiltonian by comparing theoretical results in small system sizes with experimental observations. For larger-size systems of 16 ions and 16 phonon modes, the effective Hilbert space dimension exceeds 2^{57}, whose dynamics is intractable for classical supercomputers.

Quantum Simulation of the Two-Dimensional Weyl Equation in a Magnetic Field.

Quantum simulation of 1D relativistic quantum mechanics has been achieved in well-controlled systems like trapped ions, but properties like spin dynamics and response to external magnetic fields that appear only in higher dimensions remain unexplored. Here we simulate the dynamics of a 2D Weyl particle. We show the linear dispersion relation of the free particle and the discrete Landau levels in a magnetic field, and we explicitly measure the spatial and spin dynamics from which the conservation of helicity and properties of antiparticles can be verified. Our work extends the application of an ion trap quantum simulator in particle physics with the additional spatial and spin degrees of freedom.

Differentially expressed proteins identified by TMT proteomics analysis in children with verrucous epidermal naevi.

BACKGROUND: Verrucous epidermal naevi (VEN) are benign skin tumours, considered keratinocytic epidermal naevi, that appear at birth or early childhood. VEN may display a range of appearances, depending on patient age. Although the number of studies regarding VEN is increasing, the exact mechanism of VEN is still unknown. OBJECTIVES: The aim of this study was to analyse the changes in the expression of protein factors in lesions of VEN children by TMT labelling-based quantitative proteomics. METHODS: A total of 8 children with VEN (5 for experiment and 3 for validation) and 8 healthy children (5 for experiment and 3 for validation) presented to the Department of Dermatology, the First Affiliated Hospital of Anhui Medical University, Boao Super Hospital, between January 2019 and November 2019. The lesions and lesion-adjacent tissues from children with VEN and naevus-adjacent normal skin tissues from children with pigmented naevi were defined as the VEN group, VENC group and C group, respectively. We performed a proteomics analysis to screen for differentially expressed proteins in the lesions of these individuals. We further performed Western blotting to validate the relative expression levels of nine targeted proteins in the validation group. RESULTS: According to the proteomics results, a total of 4970 proteins were identified, and 4770 proteins were quantified. Among these proteins, 586 proteins were up- or downregulated at least 1.3-fold with a P-value < 0.05 (upregulated: 399, downregulated: 187) in lesions between the VEN group and the C group. These proteins played important roles in multiple biological functions, such as cornification, epidermal cell differentiation and neutrophil activation, and formed a complicated protein-protein interaction network. Of the 586 up- or downregulated proteins, nine were selected for further validation. According to Western blotting analysis results, the relative expression levels of Involucrin, NDUFA4, Loricrin, Keratin type II cytoskeletal 6A (Cytokeratin 6A), BRAF, Filaggrin, S100A7 and Desmocollin-3 were significantly upregulated in VEN children and may be associated with skin barrier dysfunction, epidermal cell overgrowth and differentiation, inflammation and immune and oxidative phosphorylation, which are involved in the pathogenesis of VEN. CONCLUSIONS: According to TMT-based proteomics and Western blotting results, we identified eight noteworthy proteins, Involucrin, NDUFA4, Loricrin, Keratin type II cytoskeletal 6A, BRAF, Filaggrin, S100A7 and Desmocollin-3, that were upregulated in the lesions of VEN children and may be associated with the pathogenesis of VEN. Our findings provide new starting points for identifying precise pathogenic mechanisms or therapeutic targets for VEN.

First Report of Brown Rot of Apricot Caused by Monilia mumecola.

In May 2013, apricot (Prunus armeniaca) fruits covered with grayish, conidial masses were collected from an unknown cultivar in an experimental field of Huazhong Agricultural University, Wuhan, Hubei Province. About 3 to 5% of fruit was infected and affected apricots had tan to white zones of sporulation, which resembled brown rot caused by Monilia species. Conidia were harvested from the surface of the sporulating apricot fruit and spread onto shallow potato dextrose agar (PDA) media (about 2 mm in thickness) using sterile cotton swabs. Conidia were lemon-shaped and mean size was 15.7 (10 to 22.5) × 25 (16.25 to 35) µm. Conidia on PDA were incubated at 23°C for 3 h in darkness, then observed under microscope. More than two germ tubes were produced from each conidium, which was the distinctive trait of Monilia mumecola species (2). Single-spore isolates were obtained and 3 isolates were cultured on PDA in petri dishes. Mycelium grew at an average of 15 mm per day, and the colony showed concentric rings of mycelium with lobbed margins at 23°C in darkness. A 712-bp fragment was PCR amplified from ß-tubulin gene (TUB2) of all the nine isolates investigated indicative of M. mumecola (2). The ribosomal ITS1-5.8S-ITS2 regions of nine isolates were also PCR-amplified from genomic DNA using primers ITS1 and ITS4 and then sequenced (4). ITS sequences were identical to ITS sequences of M. mumecola from China (HQ908786) and Japan (AB125613, AB125614, and AB125620), but only has 98% and 97% identity with the closest species M. laxa (EU042149) and M. fructicola (HQ908789) according to BLAST search in GenBank. Pathogenicity was confirmed by inoculating mycelial plugs of three isolates into six surface-sterilized apricots wounded with a 6-mm diameter sterile cork borer. Control fruit received plain PDA plugs and was incubated in a moist chamber at 23°C with 12 h light/12 h dark. All inoculated fruit developed typical brown rot symptoms with sporulating areas as described above after 3 days of incubation, while control fruits remained healthy. The developing spores on inoculated fruit were re-isolated and confirmed to be M. mumecola. M. mumecola was first isolated from Prunus mume in Japan in 1982 as an unknown Monilia species (3), then identified and the nomenclature was provided in 2004 (1). To our knowledge, this is the first report of M. mumecola on P. armeniaca indicating that M. mumecola has spread to different hosts. References: (1) Y. Harada et al. J. Gen. Plant Pathol. 70:297, 2004. (2) M. J. Hu et al. Plos One, 6(9):e24990, 2011. (3) S. Nakao. Kongetsu-no-noyaku, 1:92, 1992. (4) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, 1990.

[Progress in the application of artificial intelligence in gastric cancer imaging].

Gastric cancer is a common malignant tumor of digestive tract, and its prognosis varies greatly with different stages of the tumor. In recent years, more and more evidence shows that artificial intelligence (AI) technology has excellent performance in imaging diagnostic applications, with remarkable diagnostic effects and broad prospects. AI not only improves the accuracy of diagnosis and staging of gastric cancer, but also has great application value in pathological assessment, adjuvant therapy and prognosis prediction. This article systematically reviews domestic and foreign literature to explore the application progress of AI in gastric cancer imaging.

Observation of supersymmetry and its spontaneous breaking in a trapped ion quantum simulator.

Supersymmetry (SUSY) helps solve the hierarchy problem in high-energy physics and provides a natural groundwork for unifying gravity with other fundamental interactions. While being one of the most promising frameworks for theories beyond the Standard Model, its direct experimental evidence in nature still remains to be discovered. Here we report experimental realization of a supersymmetric quantum mechanics (SUSY QM) model, a reduction of the SUSY quantum field theory for studying its fundamental properties, using a trapped ion quantum simulator. We demonstrate the energy degeneracy caused by SUSY in this model and the spontaneous SUSY breaking. By a partial quantum state tomography of the spin-phonon coupled system, we explicitly measure the supercharge of the degenerate ground states, which are superpositions of the bosonic and the fermionic states. Our work demonstrates the trapped-ion quantum simulator as an economic yet powerful platform to study versatile physics in a single well-controlled system.

Observation of a quantum phase transition in the quantum Rabi model with a single trapped ion.

Quantum phase transitions (QPTs) are usually associated with many-body systems in the thermodynamic limit when their ground states show abrupt changes at zero temperature with variation of a parameter in the Hamiltonian. Recently it has been realized that a QPT can also occur in a system composed of only a two-level atom and a single-mode bosonic field, described by the quantum Rabi model (QRM). Here we report an experimental demonstration of a QPT in the QRM using a 171Yb+ ion in a Paul trap. We measure the spin-up state population and the average phonon number of the ion as two order parameters and observe clear evidence of the phase transition via adiabatic tuning of the coupling between the ion and its spatial motion. An experimental probe of the phase transition in a fundamental quantum optics model without imposing the thermodynamic limit opens up a window for controlled study of QPTs and quantum critical phenomena.

Proton resonance assignments for Pseudomonas aeruginosa ferrocytochrome c-551.

A comparison between two sets of resonance assignments for ferrocytochrome c-551 from Pseudomonas aeruginosa reveals that major differences can be explained by pH effects. In turn, these reveal side chain protonation events in c-551 that markedly influence spectra. The behavior of resonances in a homologous protein from Pseudomonas stutzeri help to clarify ambiguities in the P. aeruginosa case. A corrected and completed set of proline assignments is presented. Labile side chain protons in residue 47, which hydrogen bonds to the inner heme propionate, appear to be in fast exchange with the solvent.

NMR comparison of prokaryotic and eukaryotic cytochromes c.

1H NMR spectroscopy has been used to examine ferrocytochrome c-551 from Pseudomonas aeruginosa (ATCC 19429) over the pH range 3.5-10.6 and the temperature range 4-60 degrees C. Resonance assignments are proposed for main-chain and side-chain protons. Comparison of results for cytochrome c-551 to recently assigned spectra for horse cytochrome c (Wand et al. (1989) Biochemistry 28, 186-194) and mutants of yeast iso-1 cytochrome (Pielak et al. (1988) Eur. J. Biochem. 177, 167-177) reveals some unique resonances with unusual chemical shifts in all cytochromes that may serve as markers for the heme region. Results for cytochrome c-551 indicate that in the smaller prokaryotic cytochrome, all benzoid side chains are rapidly flipping on the NMR time scale. In contrast, in eukaryotic cytochromes there are some rings flipping slowly on the NMR time scale. The ferrocytochrome c-551 undergoes a transition linked to pH with a pK around 7. The pH behavior of assigned resonances provides evidence that the site of protonation is the inner or buried 17-propionic acid heme substituent (IUPAC-IUB porphyrin nomenclature). Conformational heterogeneity has been observed for segments near the inner heme propionate substituent.

Electron self-exchange in Pseudomonas cytochromes.

Electron self-exchange has been measured by an NMR technique for cytochromes c551 from Pseudomonas aeruginosa and Pseudomonas stutzeri. The rate for P. aeruginosa cyt c551 is 1.2 x 10(7) M-1 s-1 at 40 degrees C in 50 mM phosphate at pH 7. For P. stutzeri, under the same conditions, the rate is 4 x 10(7) M-1 s-1. For both cytochromes, the rate was independent of ionic strength up to 0.5 M in added NaC1, the enthalpy of activation was 20 +/- 4 kcal mol-1, and the entropy of activation was 38 +/- 10 cal mol-1 deg-1.