The lifetime of localized surface plasmon plays an important role in many aspects of plasmonics and its applications. In small metal nanostructures, the dominant mechanism restricting plasmon lifetime is size-dependent Landau damping. We performed quantum-mechanical calculations of Landau damping for the bright surface plasmon mode in a metal nanoshell. In contrast to the conventional model based on the electron surface scattering, we found that the damping rate decreases as the nanoshell thickness is reduced. The origin of this behavior is traced to the spatial distribution of plasmon local field inside the metal shell. We also found that, due to interference of electron scattering amplitudes from nanoshell's two metal surfaces, the damping rate exhibits pronounced quantum beats with changing shell thickness.
Resonanant enhancement of molecular excitation intensity in inelastic electron scattering spectrum owing to interaction with plasmons in metallic nanoshell
Tho-photon absorption holds potential for many practical applications. We theoretically investigate the onset of this phenomenon in a semiconductor quantum dot -- metallic nanoshell composite subjected to a resonant CW excitation. Two-photon absorption in this system may occur in two ways: incoherent -- due to a consecutive ground-to-one-exciton-to-biexciton transition and coherent -- due to a coherent two-photon process, involving the direct ground-to-biexciton transition in the quantum dot. The presence of the nanoshell nearby the quantum dot gives rise to two principal effects: (i) -- renor…
A recent study shows that: when a long lifetime particle is positioned near a plasmonic metal nanoparticle, lifetime of plasmon oscillations extends, but, "only" near that long-life particle [PRB 101, 035416 (2020)]. Here, we show that this phenomenon can be utilized for ultrahigh (single-molecule) resolution ultrafast apertureless (scattering) SNOM applications. We use the exact solutions of 3D Maxwell equations. We illuminate a metal-coated silicon tip, a quantum emitter (QE) placed on the tip apex, with a femtosecond laser. The induced near-field in the apex decays rapidly except in the vic…
The distance-dependent interaction of an emitter with a plasmonic nanoparticle or surface forms the basis of the field of plexitonics. Semiconductor quantum dots (QDs) are robust emitters due to their photostability, and offer the possibility of understanding the fundamental photophysics between one emitter and one metal nanoparticle. A key enabling challenge is the formation of systems containing both QDs and plasmonic nanoparticles in high purity. We present the translation of DNA-based self-assembly techniques to assemble metal and semiconductor nanocrystals into discrete hybrid structures,…
We report a new way to slow down the spontaneous emission rate of excitons in the wetting layer (WL) through radiative field coupling between the exciton emissions and the dipole field of metal islands. As a result, a long-lifetime decay process is detected in the emission of InAs/GaAs single quantum dots (QDs). It is found that when the separation distance from WL layer (QD layer) to the metal islands is around 20 nm and the islands have an average size of approximately 50 nm, QD lifetime may change from approximately 1 to 160 ns. The corresponding second-order autocorrelation function g(2) (…
Tight-binding terahertz plasmons in chemical vapor deposited graphene
包括石墨烯和亚波长金属光栅的晶体管结构对于等离子体激元增强的太赫兹检测具有很大的希望。尽管有相当多的理论研究，但到目前为止，在这种结构中几乎没有发现太赫兹等离子体激元的实验证据。在这里，我们报告了在石墨烯绝缘体光栅结构中使用傅里叶变换光谱在5-10太赫兹范围内的等离子体激元的实验研究。即使在具有低载流子迁移率$\sim 10^3$ cm $^2$ /（Vs）的化学气相沉积（CVD）石墨烯中，等离子体共振在Drude吸收背景之上也是清晰可见的。我们认为，等离子体激元寿命是弱敏感的散射晶界和宏观缺陷，限制了CVD样品的流动性。在将光栅放置在石墨烯附近时，等离子体激元场变得紧密地束缚在金属条下方，而谐振频率由条宽度而不是光栅周期确定。我们的研究结果打开了大面积商用石墨烯共振太赫兹探测器的前景。
Graphene has emerged as a promising platform to bring nonlinear quantum optics to the nanoscale, where a large intrinsic optical nonlinearity enables long-lived and actively tunable plasmon polaritons to strongly interact. Here we theoretically study the collision between two counter-propagating plasmons in a graphene nanoribbon, where transversal subwavelength confinement endows propagating plasmons with %large effective masses a flat band dispersion that enhances their interaction. This scenario presents interesting possibilities towards the implementation of multi-mode polaritonic gates tha…
Understanding plasmon dispersion in nearly-free-electron metals: the relevance of exact constraints for novel exchange-correlation kernels within time-dependent density functional theory
We investigate the two-plasmon spontaneous decay of a quantum emitter near single-walled carbon nanotubes (SWCNT) and graphene-coated wires (GCWs). We demonstrate efficient, enhanced generation of two-plasmon entangled states in SWCNTs due to the strong coupling between tunable guided plasmons and the quantum emitter. We predict two-plasmon emission rates more than twelve orders of magnitude higher than in free-space, with average lifetimes of a few dozens of nanoseconds. Given their low dimensionality, these systems could be more efficient for generating and detecting entangled plasmons in co…
