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Quantum state preparation (QSP) is an essential step in many quantum information processing tasks and has been deeply studied in a closed system. However, environmental noise inevitably destroys the quantumness of the system, resulting in decreased fidelity. In this work, we investigate the enhancement of fidelity by pulse control for arbitrary single or two-qubit QSP in a noisy environment. The control pulses are designed by leveraging supervised learning. The environment is modeled as a collection of bosons, and we use the quantum state diffusion equation technique to deal with the dynamics of the system. We consider two types of noise: quasistatic noise and dynamic noise. We propose active and adaptive denoising schemes for the quasistatic and dynamic noise, respectively. The environmental parameters are required to construct the dataset when training the neural network (NN) in adaptive denoising, while they are not needed in active denoising. The adaptive denoising scheme is universal in that it can be effectively applied to both quasistatic and dynamic noises. High-fidelity QSP has been obtained by the well-trained NN. Our work demonstrates that machine learning has great potential in optimal pulse design in a dynamic environment.

Pulse-controlled non-adiabatic quantum state transmission (QST) was proposed many years ago. However, in practice environmental noise inevitably damages communication quality in the proposal. In this paper, we study the optimally controlled non-adiabatic QST in the presence of quantum noise. By using the Adam algorithm, we find that the optimal pulse sequence can dramatically enhance the transmission fidelity of such an open system. In comparison with the idealized pulse sequence in a closed system, it is interesting to note that the improvement of the fidelity obtained by the Adam algorithm can even be better for a bath strongly coupled to the system. Furthermore, we find that the Adam algorithm remains powerful for different numbers of sites and different types of Lindblad operators, showing its universality in performing optimal control of quantum information processing tasks.

We investigate the time-dependent behaviour of the energy current between a quantum spin chain and its surrounding non-Markovian and finite temperature baths, together with its relationship to the coherence dynamics of the system. To be specific, both the system and the baths are assumed to be initially in thermal equilibrium at temperature Ts and Tb, respectively. This model plays a fundamental role in study of quantum system evolution towards thermal equilibrium in an open system. The non-Markovian quantum state diffusion (NMQSD) equation approach is used to calculate the dynamics of the spin chain. The effects of non-Markovianity, temperature difference and system-bath interaction strength on the energy current and the corresponding coherence in cold and warm baths are analyzed, respectively. We show that the strong non-Markovianity, weak system-bath interaction and low temperature difference will help to maintain the system coherence and correspond to a weaker energy current. Interestingly, the warm baths destroy the coherence while the cold baths help to build coherence. Furthermore, the effects of the Dzyaloshinskii–Moriya (DM) interaction and the external magnetic field on the energy current and coherence are analyzed. Both energy current and coherence will change due to the increase of the system energy induced by the DM interaction and magnetic field. Significantly, the minimal coherence corresponds to the critical magnetic field which causes the first order phase transition.

A novel dual air-gap transverse-flux six-phase permanent magnet electric machine using C-shaped configured architecture with laminated silicon steel is designed and implemented in this study. The magnetic flux density distribution and magnetic flux linkage of the C-shaped configured architecture with laminated silicon steel have been achieved to verify the design concept which leading the magnetic line in the same direction as laminated silicon steel arrangement. The notches on both stators and rotors are designed aiming at lowering down cogging torque and compared with a normal permanent magnet electric machine. The optimal combination is resulted in the cogging torque reduction of 70.2%, and the output torque reduction is 6.5%. Additionally, a new model-free predictive current control, insensitive to parameter variations of the electric machines, is proposed to drive the permanent magnet electric machine aiming at six-phase current error reduction within 0.36 A. As a result, a better satisfactory current tracking ability of the proposed model-free predictive current control law in the six-phase permanent magnet electric machine has been validated successfully in experimental results.

Considering its vertical distribution characteristics, this article argues that the Lower Palaeozoic source rock in the Manjieer Sag is composed of three sets of source rocks of Middle-Lower Cambrian, Middle-Lower Ordovician, and Upper Ordovician. The source rock of the Middle-Lower Ordovician Heituwa Formation has similar sedimentary facies and developmental features to the Middle-Lower Cambrian source rock, and has abundant organic material. The Upper Ordovician source rock is poor and limited in distribution. The source rocks have different thermal evolution histories. In central and western Manjiaer sag, Middle-Lower Cambrian source rock entered oil generation peak in Late Caledonian and Early Hercynian, Middle-Lower Ordovician source rock in Late Hercynian, and Upper Ordovician source rock in Late Yanshan and Himalayan. The threefold division of the source rock is the foundation of detailed study on the derived source and the accumulation process of marine oil in Tarim platform area. Key words: Lower Palaeozoic, source rock, thermal evolution history, Manjiaer Sag, Tarim Basin

A total of 1502 samples, including feces of sheep (793) and cattle (348), pasture soil (118), dung compost (147) and barn soil (96), were examined between October 2012 and August 2014 to discover potential strains of nematophagous fungi for the biological control of livestock-parasitic nematodes. These samples were collected from 87 sites located in 48 counties of 20 provinces (autonomous regions/municipalities) of China. Fungi were identified down to a species level. Four hundred and seventy-seven isolates, which were distributed in 8 genera and 28 taxa, were identified as nematophagous fungi. Nematode-trapping fungi included 17 species and one unidentified species of Arthrobotrys, two of Dactylella, Drechslerella dactyloides, and Duddingtonia flagrans. Five identified species and two unidentified species of endoparasitic fungi were isolated. The predominant species from all regions were Arthrobotrys oligospora, followed by Arthrobotrys musiformis, Arthrobotrys ( Monacrosporium) thaumasiun, and Arthrobotrys ( Monacrosporium) microscaphoides. Species with adhesive networks were the most frequently isolated. Among the endoparasitic fungi, Podocrella harposporifera ( Harposporium anguillulae) was the most common species, followed by Harposporium lilliputanum and Harposporium arcuatum. Based on Shannon diversity index, the diversity levels of nematophagous fungi were relatively higher in samples associated with cattle, barn soil, and subtropical monsoon climate zone. Three species isolated from this study, namely, Duddingtonia flagrans, Arthrobotrys salina ( Monacrosporium salinum), and Arthrobotrys oligospora var. sarmatica, are newly recorded in China, and 20 species (including one unidentified species) are newly recorded in sheep and cattle barn soils worldwide. [ABSTRACT FROM AUTHOR]

Nematophagous fungi are considered to have the best potential as biological agents for the control of gastrointestinal nematodes in domestic animals. However, relatively few studies have been conducted with the genus Monacrosporium, especially with strains native to China. In the present study, we isolated and identified nematophagous fungi from fresh sheep feces. A pure fungal strain was molecularly characterized, and its nematophagous activity was evaluated. The morphological plasticity of the isolated strain, as well as its interaction with the nematode targets, was observed by scanning electron microscopy of the infected Trichostrongylus colubriformis L3 and the free-living nematode Caenorhabditis elegans. Three isolated fungal strains from the 30 fresh fecal samples of sheep from Inner Mongolia, China exhibited predatory activity; however, only a single strain was successfully purified (SF 0459). The SF 0459 strain was characterized by morphological analysis of its conidia and sequencing of its ITS1-5.8S rDNA-ITS2 region. This strain was identified to be Monacrosporium salinum (GenBank ID: KP036623). Nematophagous fungus helper bacteria were found at the interaction points between fungi and nematodes. The percentage of live T. colubriformis L3 was reduced by 83.79-88.69% based on the in vitro assay. [ABSTRACT FROM AUTHOR]

Desmoplastic small-round-cell tumor (DSRCT) is an uncommon type of malignancy, which primarily occurs in adolescent males and develops in the abdominal cavity. The present study reports the case of two manifestations of DSRCT complicated with other diseases, which involved the invasion of the pelvis or abdominal vessels. The first case was of a 25-year-old man with repeated diarrhea and abdominal distension for 9 months; the second case was of a 68-year-old man who presented with persistent abdominal pain for 20 days. In each patient, a mass was identified in the abdomen and biopsies were performed in order to reach a diagnosis. Immunohistochemical staining of the biopsy material revealed a diagnosis of DSRCT in each case. In addition, the present study aimed to discuss the use of imaging techniques in providing evidence for the early diagnosis of DSRCT. [ABSTRACT FROM AUTHOR]

We show that a category of one-dimensional XY-type models may enable high-fidelity quantum state transmissions, regardless of details of coupling configurations. This observation leads to a fault-tolerant design of a state transmission setup. The setup is fault-tolerant, with specified thresholds, against engineering failures of coupling configurations, fabrication imperfections or defects, and even time-dependent noises. We propose an experimental implementation of the fault-tolerant scheme using hard-core bosons in one-dimensional optical lattices. [ABSTRACT FROM AUTHOR]

We investigate the entanglement transfer in two parallel spin chains by anisotropic Heisenberg XY interaction in an external magnetic field. The perfect entanglement transfer condition is obtained. We find that perfect entanglement transfer can be realized from one spin pair to another spin pair at certain times by adjusting the magnetic field strength and the anisotropy parameter, which suggests its potential usefulness in quantum information process. [ABSTRACT FROM AUTHOR]

Original article: EPL, 125 (2019) 10010. [ABSTRACT FROM AUTHOR]

Adiabatic evolution is required in performing quantum information processing tasks and adiabatic speedup is often used to avoid decoherence problems for a long evolution time. Here, we add a leakage elimination operator (LEO) Hamiltonian to the evolution and adiabatic speedup can be obtained. LEO Hamiltonians can be realized by a sequence of periodic zero-energy-change pulses. By using the Feshbach partitioning technique, we obtain the exact control parameters to realize adiabatic speedup for different types of pulses. Furthermore, we show that this control scheme is fault-tolerant against pulse strength and pulse frequency for specified thresholds. [ABSTRACT FROM AUTHOR]

Dynamical decoupling operations have been shown to reduce errors in quantum information processing. Leakage from an encoded subspace to the rest of the system space is a particularly serious problem for which leakage elimination operators (LEOs) were introduced. Here we provide an analysis of nonideal pulses rather than the well-understood idealization or bang-bang controls. Under realistic conditions we show that these controls will provide the same protection from errors as idealized controls. Our work indicates that the effectiveness of LEOs depends on the integral of the pulse sequence in the time domain which has been missing because of the idealization of pulse sequences. Our results are applied to a three-level system for the nitrogen-vacancy centers under an external magnetic field and are illustrated by the fidelity dynamics of LEO sequences ranging from regular rectangular pulses random pulses and even disordered (noisy) pulses. [ABSTRACT FROM AUTHOR]