1,228 research outputs found

    High-fidelity Rydberg control-Z gates with time-optimal pulses

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    High-fidelity control-ZZ (CZC_Z) gates are essential and mandatory to build a large-scale quantum computer. In neutral atoms, the strong dipole-dipole interactions between their Rydberg states make them one of the pioneering platforms to implement CZC_Z gates. Here we numerically investigate the time-optimal pulses to generate a high-fidelity Rydberg CZC_{Z} gate in a three-level ladder-type atomic system. By tuning the temporal shapes of Gaussian or segmented pulses, the populations on the intermediate excited states are shown to be suppressed within the symmetric gate operation protocol, which leads to a CZC_{Z} gate with a high Bell fidelity up to 0.99980.9998. These optimized pulses are robust to thermal fluctuations and the excitation field variations. Our results promise a high-fidelity and fast gate operation under amenable and controllable experimental parameters, which goes beyond the adiabatic operation regime under a finite Blockade strength.Comment: 6 figure

    On the Miura map between the dispersionless KP and dispersionless modified KP hierarchies

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    We investigate the Miura map between the dispersionless KP and dispersionless modified KP hierarchies. We show that the Miura map is canonical with respect to their bi-Hamiltonian structures. Moreover, inspired by the works of Takasaki and Takebe, the twistor construction of solution structure for the dispersionless modified KP hierarchy is given.Comment: 19 pages, Latex, no figure

    TIME millimeter wave grating spectrometer

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    The Tomographic Ionized-carbon Mapping Experiment (TIME) utilizes grating spectrometers to achieve instantaneous wideband coverage with background-limited sensitivity. A unique approach is employed in which curved gratings are used in parallel plate waveguides to focus and diffract broadband light from feed horns toward detector arrays. TIME will measure singly ionized carbon fluctuations from 5 < z < 9 with an imaging spectrometer. 32 independent spectrometers are assembled into two stacks of 16, one per polarization. Each grating has 210 facets and provides a resolving power R of ~ 200 over the 186–324 GHz frequency range. The dispersed light is detected using 2-D arrays of transition edge sensor bolometers. The instrument is housed in a closed-cycle 4K–1K–300mK cryostat. The spectrometers and detectors are cooled using a dual-stage 250/300 mK refrigerator

    Role of tissue transglutaminase 2 in the acquisition of a mesenchymal-like phenotype in highly invasive A431 tumor cells

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    <p>Abstract</p> <p>Background</p> <p>Cancer progression is closely linked to the epithelial-mesenchymal transition (EMT) process. Studies have shown that there is increased expression of tissue tranglutaminase (TG2) in advanced invasive cancer cells. TG2 catalyzes the covalent cross-linking of proteins, exhibits G protein activity, and has been implicated in the modulation of cell adhesion, migration, invasion and cancer metastasis. This study explores the molecular mechanisms associated with TG2's involvement in the acquisition of the mesenchymal phenotype using the highly invasive A431-III subline and its parental A431-P cells.</p> <p>Results</p> <p>The A431-III tumor subline displays increased expression of TG2. This is accompanied by enhanced expression of the mesenchymal phenotype, and this expression is reversed by knockdown of endogenous TG2. Consistent with this, overexpression of TG2 in A431-P cells advanced the EMT process. Furthermore, TG2 induced the PI3K/Akt activation and GSK3β inactivation in A431 tumor cells and this increased Snail and MMP-9 expression resulting in higher cell motility. TG2 also upregulated NF-κB activity, which also enhanced Snail and MMP-9 expression resulting in greater cell motility; interestingly, this was associated with the formation of a TG2/NF-κB complex. TG2 facilitated acquisition of a mesenchymal phenotype, which was reversed by inhibitors of PI3K, GSK3 and NF-κB.</p> <p>Conclusions</p> <p>This study reveals that TG2 acts, at least in part, through activation of the PI3K/Akt and NF-κB signaling systems, which then induce the key mediators Snail and MMP-9 that facilitate the attainment of a mesenchymal phenotype. These findings support the possibility that TG2 is a promising target for cancer therapy.</p

    A Postverification Method for Solving Forced Duffing Oscillator Problems without Prescribed Periods

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    This paper proposes a postverification method (PVM) for solving forced Duffing oscillator problems without prescribed periods. Comprising a postverification procedure and small random perturbation, the proposed PVM improves the sensitivity of the convergence of Newton’s iteration. Numerical simulations revealed that the PVM is more accurate and robust than Kubíček’s approach. We applied the PVM to previous research on bifurcation problems
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