354 research outputs found

    Observation of Quantum Capacitance of individual single walled carbon nanotubes

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    We report a measurement on quantum capacitance of individual semiconducting and small band gap SWNTs. The observed quantum capacitance is remarkably smaller than that originating from density of states and it implies a strong electron correlation in SWNTs

    Determination of the Sign of g factors for Conduction Electrons Using Time-resolved Kerr Rotation

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    The knowledge of electron g factor is essential for spin manipulation in the field of spintronics and quantum computing. While there exist technical difficulties in determining the sign of g factor in semiconductors by the established magneto-optical spectroscopic methods. We develop a time resolved Kerr rotation technique to precisely measure the sign and the amplitude of electron g factor in semiconductors

    The generalized Kloosterman's sums and its fourth power mean

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    The main purpose of this article is to study the calculating problem of one kind fourth power mean of the generalized Kloosterman's sums and provide an accurate calculating formula for it utilizing analytical methods and character sums' properties. Simultaneously, the work also provides a fresh and valuable approach for researching the related power mean problem

    Concurrency attacks

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    Just as errors in sequential programs can lead to security exploits, errors in concurrent programs can lead to concurrency attacks. In this paper, we present an in-depth study of concurrency attacks and how they may affect existing defenses. Our study yields several interesting findings. For instance, we find that concurrency attacks can corrupt non-pointer data, such as user identifiers, which existing memory-safety defenses cannot handle. Inspired by our findings, we propose new defense directions and fixes to existing defenses.

    Anomalously Robust Valley Polarization and Valley Coherence in Bilayer WS2

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    Coherence is a crucial requirement to realize quantum manipulation through light-matter interactions. Here we report the observation of anomalously robust valley polarization and valley coherence in bilayer WS2. The polarization of the photoluminescence from bilayer WS2 inherits that of the excitation source with both circularly and linearly polarized and retains even at room temperature. The near unity circular polarization of the luminescence reveals the coupling of spin, layer and valley degree of freedom in bilayer system, while the linear polarized photoluminescence manifests quantum coherence between the two inequivalent band extrema in momentum space, namely, the valley quantum coherence in atomically thin bilayer WS2. This observation opens new perspectives for quantum manipulation in atomically thin semiconductors
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