31 research outputs found

    Giant fifth-order nonlinearity via tunneling induced quantum interference in triple quantum dots

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    Schemes for giant fifth-order nonlinearity via tunneling in both linear and triangular triple quantum dots are proposed. In both configurations, the real part of the fifth-order nonlinearity can be greatly enhanced, and simultaneously the absorption is suppressed. The analytical expression and the dressed states of the system show that the two tunnelings between the neighboring quantum dots can induce quantum interference, resulting in the giant higher-order nonlinearity. The scheme proposed here may have important applications in quantum information processing at low light level

    Controlling optical bistability via interacting double dark resonances in linear quantum dot molecules

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    The behavior of optical bistability (OB) in linear triple quantum dot molecules (QDMs) using double tunneling coupling by means of a unidirectional ring cavity is investigated. The linear and nonlinear susceptibilities of the system are also investigated. The double tunneling between the quantum dots can induce the interaction of double dark resonances, which can enhance the nonlinear response of the system. The type, the hysteresis loop, and the threshold of OB can be controlled by the intensity of the double tunneling and the detuning of the probe field. Our results give insights for future experiments and applications in optics using QDMs. (C) 2014 Optical Society of Americ

    Tunneling induced dark states and the controllable resonance fluorescence spectrum in quantum dot molecules

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    Optical spectroscopy, a powerful tool for probing and manipulating quantum dots (QDs), has been used to investigate the resonance fluorescence spectrum from linear triple quantum dot molecules controlled by tunneling, using atomic physics methods. Interesting features such as quenching and narrowing of the fluorescence are observed. In such molecules the tunneling between the quantum dots can also induce a dark state. The results are explained by the transition properties of the dressed states generated by the coupling of the laser and the tunneling. Unlike the atomic system, in such quantum dot molecules quantum coherence can be induced using tunneling, requiring no coupling lasers, which will allow tunneling controllable quantum dot molecules to be applied to quantum optics and photonics

    Giant Kerr nonlinearity induced by tunneling in triple quantum dot molecules

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    A scheme for giant enhancement of the Kerr nonlinearity in linear triple quantum dot molecules is proposed. In such a system, the tunneling-induced transparency window obtained in double quantum dot molecules splits into two windows, due to the coupling with the third quantum dot. And most important, the Kerr nonlinearity can be enhanced by several orders of magnitude, compared with that generated in double quantum dot molecules. With proper detuning of the tunneling, giant Kerr nonlinearity accompanied by vanishing absorption can be realized, which opens the possibility to enhance self-phase modulation in tunneling controllable semiconductor nanostructures under conditions of low light levels. Quantitative analysis shows that the giant Kerr nonlinearity is attributed to the interacting double dark resonances induced by the tunneling between the triple quantum dots, therefore no extra laser fields are required. (C) 2014 Optical Society of Americ

    Studies on the crosslinking of electrospun starch nanofibers

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    The starch nanofiber mats were prepared by electrospinning, and crosslinked by deal with glutaraldehyde vapor in a sealed containers. The morphology and structure of the fibers (before and after crosslinking) were characterized by SEM and FT-IR, and the properties of the product were measured by tensile test and contact angle measurements. Test results show that, acetalization reaction occurred between the intermolecular of glutaraldehyde and starch, the morphology of crosslinked fibers can be grossly preserved compared with the uncrosslinked starch fibers, and tensile properties and water resistance of the fiber mats have been greatly improved after glutaraldehyde crosslinking
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