Equivalent qubit dynamics under classical and quantum noise

We study the dynamics of quantum systems under classical and quantum noise, focusing on decoherence in qubit systems. Classical noise is described by a random process leading to a stochastic temporal evolution of a closed quantum system, whereas quantum noise originates from the coupling of the microscopic quantum system to its macroscopic environment. We derive deterministic master equations describing the average evolution of the quantum system under classical continuous-time Markovian noise and two sets of master equations under quantum noise. Strikingly, these three equations of motion are shown to be equivalent in the case of classical random telegraph noise and proper quantum environments. Hence fully quantum-mechanical models within the Born approximation can be mapped to a quantum system under classical noise. Furthermore, we apply the derived equations together with pulse optimization techniques to achieve high-fidelity one-qubit operations under random telegraph noise, and hence fight decoherence in these systems of great practical interest.Comment: 5 pages, 2 figures; converted to PRA format, added Fig. 2, corrected typo

Free vibration of symmetric angly-plane layered truncated conical shells under classical theory

Truncated conical shell finds wide ranging of engineering applications. They are used in space crafts, robots, shelters, domes, tanks, nozzles and in machinery devices. Thus, the study of their vibrational characteristics has long been of interest for the designers. The use of the lamination for the structures leads to design with the maximum reliability and minimum weight. Moreover, the study of free vibration of laminated conical shells has been treated by a number of researchers. Irie et al. (1982) studied free vibration of conical shells with variable thickness using Rayleigh-Ritz method of solution. Wu and Wu (2000) provided 3D elasticity solutions for the free vibration analysis of laminated conical shells by an asymptotic approach. Wu and Lee (2001) studied the natural frequencies of laminated conical shells with variable stiffness using the differential quadrature method under first-order shear deformation theory (FSDT). Tripathi et al. (2007) studied the free vibration of composite conical shells with random material properties of the finite element method. Civalek (2007) used the Discrete Singular Convolution (DSC) to investigate the frequency response of orthotropic conical and cylindrical shells. Sofiyez et al. (2009) studied the vibrations of orthotropic non-homogeneous conical shells with free boundary conditions. Ghasemi et al. (2012) presented their study of free vibration of composite conical shells which was investigated under various boundary conditions using the solution of beam function and Galerkin method. Viswanathan et al. (2007, 2011) studied free vibration of laminated cross-ply plates, including shear deformation, symmetric angle-ply laminated cylindrical shells of variable thickness with shear deformation theory using the spline collocation method. In the present work, free vibration of symmetric angle-ply laminated truncated conical shells is analyzed and displacement functions are approximated using cubic and quantic spline and collocation procedure is applied to obtain a set of field equations. The field equations along with the equations of boundary conditions yield a system of homogeneous simultaneous algebraic equations on the assumed spline coefficients which resulting to the generalized eigenvalue problem. This eigenvalue problem is solved using eigensolution technique to get as many eigenfrequencies as required. The effect of circumferential mode number, length ratio, cone angle, ply angles and number of layers under two boundary conditions on the frequency parameter is studied for three- and five- layered conical shells consisting of two types of layered materials

Low-temperature characterization of Nb-Cu-Nb weak links with Ar ion-cleaned interfaces

We characterize niobium-based lateral Superconductor (S) - Normal metal (N) - Superconductor weak links through low-temperature switching current measurements and tunnel spectroscopy. We fabricate the SNS devices in two separate lithography and deposition steps, combined with strong argon ion cleaning before the normal metal deposition in the last step. Our SNS weak link consists of high-quality sputtered Nb electrodes that are contacted with evaporated Cu. The two-step fabrication flow enables great flexibility in the choice of materials and pattern design. A comparison of the temperature-dependent equilibrium critical supercurrent with theoretical predictions indicates that the quality of the Nb-Cu interface is similar to that of evaporated Al-Cu weak links. Aiming at increased sensitivity, range of operation temperatures, and thermal isolation, we investigate how these SNS structures can be combined with shadow-evaporated aluminum tunnel junctions for sensor applications that utilize the superconducting proximity effect. To this end, we demonstrate a hybrid magnetic flux sensor based on a Nb-Cu-Nb SNS junction, where the phase-dependent normal metal density of states is probed with an Al tunnel junction.Comment: 5 pages, 3 figure

Modelling of novel-structured copper barium tin sulphide thin film solar cells

[EN] In this work, a novel structured Cu2BaSnS4 (CBTS)/ZnS/Zn(O, S) photovoltaic device is proposed. A nontoxic, earth-abundant and auspicious quaternary semiconductor compound copper barium tin sulphide (Cu2BaSnS4) is used as an absorber layer. We propose a novel Zn(O, S) buffer layer for a high-power conversion efficiency (PCE) of CBTS-based thin film photovoltaic cells. Solar cell capacitance simulator software is used for device modelling and simulations are performed under a 1.5 AM illumination spectrum. The proposed device is investigated by means of numerical modelling and optimized the parameters to maximize its efficiency. Promising optimized functional parameters had been achieved from the proposed structure with back surface field layer with a PCE of 18.18%, a fill factor of 83.45%, a short-circuit current of 16.13 mA cm¿2 and an open-circuit voltage of 1.3 V. The promising results give an imperative standard for possible manufacturing of high efficiency, eco-friendly inorganic CBTS-based photovoltaic cells.This work was supported by Ministerio de Economia y Competitividad (ENE2016-77798-C4-2-R) and Generalitat valenciana (Prometeus 2014/044).Hameed, KY.; Baig, F.; Toura, H.; Marí, B.; Beg, S.; Khani, NAK. (2019). Modelling of novel-structured copper barium tin sulphide thin film solar cells. Bulletin of Materials Science. 42(5):1-8. https://doi.org/10.1007/s12034-019-1919-9S18425Ge J, Koirala P, Grice C R, Roland P J, Yu Y, Tan X et al 2017 Adv. Energy Mater. 7 1601803Khattak Y H, Mahmood T, Alam K, Sarwar T, Ullah I and Ullah H 2014 Am. J. Electr. Power Energy Syst. 3 86Steinmann V, Brandt R E and Buonassisi T 2015 Nat. Photonics 9 355Jackson P, Hariskos D, Wuerz R, Kiowski O, Bauer A, Friedlmeier T M et al 2015 Phys. Status Solidi: Rapid. Res. Lett. 9 28Shin D, Saparov B and Mitzi D B 2017 Adv. Energy Mater. 7 1602366Paper C, Le A, Universit D, Universit B, Universit M A, Marchionna S et al 2017 Eur. Photovolt. Sol. Energy Conf. 33 25Khattak Y H, Baig F, Ullah S, Marí B, Beg S and Ullah H 2018 J. Renew. Sustain. Energy 10 033501Fontané X, Izquierdo-Roca V, Saucedo E, Schorr S, Yukhymchuk V O, Valak M Y et al 2012 J. Alloys Compd. 539 190Zhang X, Bao N, Ramasamy K, Wang Y-H A, Yifeng Wang B L and Gupta A 2012 Chem. Commun. 48 4956Adewoyin A D, Olopade M A and Chendo M 2017 Optik—Int. J. Light Electron Opt. 133 122Boutebakh F Z, Zeggar M L, Attaf N and Aida M S 2017 Optik—Int. J. Light Electron Opt. 144 180Ananthakumar S, Ram Kumar J and Moorthy Babu S 2016 Optik—Int. J. Light Electron Opt. 127 10360Jianjun L, Dongxiao W, Xiuling L and Zeng Y 2018 Adv. Sci. 5 1700744Khattak Y H, Baig F, Ullah S, Marí B, Beg S and Ullah H 2018 Optik—Int. J. Light Electron Opt. 164 547Xiao Z, Meng W, Li J V. and Yan Y 2017 ACS Energy Lett. 2 29Shin D, Saparov B, Zhu T, Huhn W P, Blum V and Mitzi D B 2016 Chem. Mater. 28 477Repins I L, Romero M J, Li J V, Wei S-H, Kuciauskas D, Jiang C-S et al 2013 J. Photovoltaics 3 439Zhou H, Hsu W-C, Duan H-S, Bob B, Yang W, Song T-B et al 2013 Energy Environ. Sci. 6 2822Khattak Y H, Baig F, Toura H, Ullah S, Marí B, Beg S et al 2018 Curr. Appl. Phys. 18 633Ge J, Roland P J, Koirala P, Meng W, Young J L, Petersen R et al 2017 Chem. Mater. 29 916Ge J and Yan Y 2017 J. Mater. Chem. C 5 6406Hong F, Lin W, Meng W and Yan Y 2016 Phys. Chem. Chem. Phys. 18 4828Todorov T, Gunawan O and Guha S 2016 Mol. Syst. Des. Eng. 1 370Baig F, Ullah H, Khattak Y H and Mari Soucase B 2016 Int. Ren. Sus. En. Conf. 596, https://doi.org/10.1109/IRSEC.2016.7983899Lin L-Y, Qiu Y, Zhang Y and Zhang H 2016 Chinese Phys. Lett. 33 10780Platzer B C, Törndahl T, Abou-Ras D, Malmström J, Kessler J and Stolt L 2006 J. Appl. Phys. 100 044506Persson C, Platzer-Björkman C, Malmström J, Törndahl T and Edoff M 2006 Phys. Rev. Lett. 97 146403Burgelman M, Nollet P and Degrave S 2000 Thin Solid Films 361 527Khattak Y H, Baig F, Soucase B M and Beg S 2018 Mater. Focus 84 758Simya O K, Mahaboobbatcha A and Balachander K A 2015 Superlattices Microstruct. 82 248Shin D, Zhu T, Huang X, Gunawan O, Blum V and Mitzi D B 2017 Adv. Mater. 29 1Saha U and Alam M K 2018 Phys. Status Solidi: Rapid Res. Lett. 12 1Zhu T, Huhn W P, Wessler G C, Shin D, Saparov B, Mitzi D B et al 2017 Chem. Mater. 29 7868Ge J, Grice C R and Yan Y 2017 J. Mater. Chem. A 5 2920Baig F, Khattak Y H, Marí B, Beg S, Gillani S R and Ahmed A 2018 Optik—Int. J. Light Electron Opt. 170 463Khattak Y H, Baig F, Ullah S, Marí B, Beg S and Gillani S R 2018 Optik—Int. J. Light Electron Opt. 171 45

Candida tropicalis endocarditis successfully treated with AngioVac and micafungin followed by long-term isavuconazole suppression

We provide a review of current literature of native valve Candida tropicalis endocarditis. A 41-year old man presented with C. tropicalis candidemia complicated by superior vena cava mass and right main pulmonary artery thrombus. The patient achieved clinical and microbiologic cure with AngioVac of the mass and echinocandin for six weeks. Long-term suppression was challenging given the C. tropicalis strain was resistant to fluconazole, voriconazole and posaconazole. Additional susceptibilities were obtained and he remained relapse-free at 12 months with isavuconazole

Thermal transistor: Heat flux switching and modulating

Thermal transistor is an efficient heat control device which can act as a heat switch as well as a heat modulator. In this paper, we study systematically one-dimensional and two-dimensional thermal transistors. In particular, we show how to improve significantly the efficiency of the one-dimensional thermal transistor. The study is also extended to the design of two-dimensional thermal transistor by coupling different anharmonic lattices such as the Frenkel-Kontorova and the Fermi-Pasta-Ulam lattices. Analogy between anharmonic lattices and single-walled carbon nanotube is drawn and possible experimental realization with multi-walled nanotube is suggested.Comment: To appear in J. Phys. Soc. Jp

Suppression of 1/f noise in one-qubit systems

We investigate the generation of quantum operations for one-qubit systems under classical noise with 1/f^\alpha power spectrum, where 2>\alpha > 0. We present an efficient way to approximate the noise with a discrete multi-state Markovian fluctuator. With this method, the average temporal evolution of the qubit density matrix under 1/f^\alpha noise can be feasibly determined from recently derived deterministic master equations. We obtain qubit operations such as quantum memory and the NOT}gate to high fidelity by a gradient based optimization algorithm. For the NOT gate, the computed fidelities are qualitatively similar to those obtained earlier for random telegraph noise. In the case of quantum memory however, we observe a nonmonotonic dependency of the fidelity on the operation time, yielding a natural access rate of the memory.Comment: 8 pages, 7 figure

Structural Features Essential to the Antimicrobial Functions of Human SPLUNC1

SPLUNC1 is an abundantly secreted innate immune protein in the mammalian respiratory tract that exerts bacteriostatic and antibiofilm effects, binds to lipopolysaccharide (LPS), and acts as a fluid-spreading surfactant. Here, we unravel the structural elements essential for the surfactant and antimicrobial functions of human SPLUNC1 (short palate lung nasal epithelial clone 1). A unique α-helix (α4) that extends from the body of SPLUNC1 is required for the bacteriostatic, surfactant, and LPS binding activities of this protein. Indeed, we find that mutation of just four leucine residues within this helical motif to alanine is sufficient to significantly inhibit the fluid spreading abilities of SPLUNC1, as well as its bacteriostatic actions against Gram-negative pathogens Burkholderia cenocepacia and Pseudomonas aeruginosa. Conformational flexibility in the body of SPLUNC1 is also involved in the bacteriostatic, surfactant, and LPS binding functions of the protein as revealed by disulfide mutants introduced into SPLUNC1. In addition, SPLUNC1 exerts antibiofilm effects against Gram-negative bacteria, although α4 is not involved in this activity. Interestingly, though, the introduction of surface electrostatic mutations away from α4 based on the unique dolphin SPLUNC1 sequence, and confirmed by crystal structure, is shown to impart antibiofilm activity against Staphylococcus aureus, the first SPLUNC1-dependent effect against a Gram-positive bacterium reported to date. Together, these data pinpoint SPLUNC1 structural motifs required for the antimicrobial and surfactant actions of this protective human protein

Effect of alkali treatment of lower concentrations on the structure and tensile properties of Pakistan’s coarse cotton fibre

Cotton fibres of high Micronaire values are known to have inferior spinning performance. Either reduction of fibres’ fineness or increase in tensile strength is generally expected to improve the spinnability of fibres. In this piece of research, the effects of alkali treatment at lower concentrations (0.75–2.25M) and higher temperatures (70–100 °C) on the cross-section of cotton fibre and on the tensile strength have been investigated. Observations were made using scanning electron microscopy (SEM) and single fibre tensile strength testing. It was found that the roundness of the fibre cross section was improved and the tensile strength of the fibres also increased after treatment with alkali at lower concentration (0.75 M) and relatively lower temperature (70 °C). It is proposed that such changes occurred due to possible cellulose dissolution/transformations. It was thus concluded that the alkali treatment of cotton fibres at lower concentrations (0.75 M) and 70 °C for a shorter period of time (45 mins) could lead to improvement in tensile strength and roundness of fibre cross-section, thereby improving micronaire