The optical trapping of Au nanoparticles with dimensions as small as 10 nm in the gap of plasmonic dipole antennas is demonstrated. Single nanoparticle trapping events are recorded in real time by monitoring the Rayleigh scattering spectra of individual plasmonic antennas. Numerical simulations are also performed to interpret the experimental results, indicating the possibility to trap nanoparticles only a few nanometers in size. This work unveils the potential associated with the integration of plasmonic trapping with localized surface plasmon resonance based sensing techniques, in order to deliver analyte to specific, highly sensitive regions ("hot spots").

Near field generated by plasmonic structures has recently been proposed to trap small objects. We report the first integration of plasmonic trapping with microfluidics for lab-on-a-chip applications. A three-layer plasmo-microfluidic chip is used to demonstrate the trapping of polystyrene spheres and yeast cells. This technique enables cell immobilization without the complex optics required for conventional optical tweezers. The benefits of such devices are optical simplicity, low power consumption and compactness; they have great potential for implementing novel functionalities for advanced manipulations and analytics in lab-on-a-chip applications.

The widespread use of electronic equipment, such as computers, cell phones, communication devices and wireless facilities, has increased electromagnetic radiation, which can cause cancer and other diseases in humans. Furthermore, there is an urgent need for excluding the interferences in the aircraft and other precise instruments in military aspects. Therefore, minimizing and attenuating electromagnetic waves are critical issues. In this review, various two-dimensional (2D) materials and structures are discussed for microwave-absorbing and shielding in terms of ‘thin, light, wide, and strong’ requirements. The typical absorption and attenuation mechanisms are analysed and summarized to deliver an overall view and offer possible trends for future developments. Multiple works have revealed that 2D materials and structures are promising for use in microwave devices. In addition to conventional materials with 2D structures, we focus on new graphene-like materials, such as 2D transition metal dichalcogenides and black phosphorus, due to their beneficial absorbing and shielding properties. These 2D materials will likely play an important role in electromagnetic wave absorption and cancellation in the future. Finally, the related challenges and some new 2D materials are briefly discussed.

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The resonance fluorescence of a two-level single molecular system interacting with a plasmonic nanostructure is investigated. Specific regions of space are identified, where a balance exists between the near-field enhancement and the modification of the decay rate, such that the fluorescence spectrum of the molecule exhibits the Mollow triplet and the emission photons are antibunched. The utilization of such quantum phenomena at the vicinity of custom-designed plasmonic nanostructures paves the way for applications in nanoscale quantum devices and quantum information processing. DOI: 10.1103/PhysRevB.81.193103 PACS number͑s͒: 82.37.Vb, 73.20.Mf, 78.67.Bf The interference of resonant transitions between atomic levels leads to many interesting quantum effects: Mollow absorption and triplet peaks, 1 electromagnetically induced transparency, 2 lasing without inversion, 3 quantum switching, 4 and spontaneous-emission cancellation.5 These effects are also exhibited by molecular systems. 6-9 For example, photon antibunching was observed in the fluorescence spectrum of pentacene molecules trapped in a solid. Autler-Townes structures were reported in pump-probe experiments of single terrylene molecules at superfluid helium temperature.8 Mollow fluorescence triplet and coherent oscillations of emission photons were observed at low temperature T = 1.4 K by strongly focusing the far-field excitation onto the extinction area of molecules. 9 In this work, instead of using far-field illumination, we utilize the dramatic nearfield enhancement provided at the vicinity of plasmonic structures to realize the strong coupling between single molecules and fields. Although molecules with complex vibration energy structures have a comparatively broad emission spectrum, the two-level approximation is perfectly well suited to describe them and has been widely used in the literature.7-9 We shall use this framework for this study. When a quantum emitter is approaching a resonant plasmonic structure, it experiences a strong near-field enhancement as well as a significant modification of the decay rate of its transition channels. 10 This modification of the population of excited state and decay rate can control the emission of fluorescent molecules and semiconductor quantum dots. 11Scanning near-field optical microscope probing of singlemolecule fluorescence indicates that near-field enhancement of resonant metallic nanoparticle leads to a change in intensity, lifetime, and spectrum of the fluorescence.12-14 Fluorescence quenching of dye molecules 15 and changes in the shape of fluorescence spectra 16 near gold nanoparticles have also been observed. When a single molecule is approaching a gold nanoparticle, a continuous transition from fluorescence enhancement to quenching is observed experimentally.12 Recently, the emission direction of a single molecule was experimentally realized by coupling the molecule to a specifically designed nanoantenna. 17Surface-dressed Bloch equations were furthermore used to study the fluorescence properties...