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We set the theoretical basis for scattering cancellation and cloaking of quantum particle waves. We discuss the possibility of cloaking a spherical object from an impinging matter wave by using a homogeneous monolayer with properly tailored effective mass and potential. The method, based on cancellation of scattered s and p waves, is the quantum analog of plasmonic cloaking of electromagnetic waves. We show that it may be possible to use this cloaking mechanism to make semiconductor quantum dots effectively invisible to impinging electrons, providing interesting venues in nano-optics, quantum computing, and furtive quantum sensing. [ABSTRACT FROM AUTHOR]

Enhancement of molecular emission is usually obtained by coupling small optical emitters with external resonant structures and systems, as first established by Purcell several decades ago, and verified in several recent investigations using molecules or quantum dots coupled with plasmonic nanoantennas. Here we theoretically investigate in detail a different mechanism for emission enhancement, based on our recent idea of a plasmonic nanolauncher [Phys. Rev. Lett. 2009, 103, 043902], i.e., a metamaterial-inspired ultranarrow waveguide channel operating near its cut-off frequency. Such system is not necessarily at resonance, but its peculiar operation may provide enhanced emission over a relatively broad physical area, which may allow enhancement of emission independent of the position of an individual or of a group of molecules along such plasmonic channel, and the possibility to bend and route the emitted energy with large flexibility. We present here extensive theoretical and numerical results that confirm this intuition and may envision a novel method for molecular emission enhancement at the nanoscale, with more flexibility than the conventional Purcell resonance techniques. [ABSTRACT FROM AUTHOR]