No abstract

Surface plasmon polaritons (SPPs) may serve as ultimate data processing expedients in future nanophotonic applications. SPPs combine the high localization of electrons with the bandwidth, frequency and propagation properties of photons, thus supplying nature with the best of two worlds. However, although plasmonics have recently gained constantly growing scientific attention, logic devices that operate on SPPs on a deep nanometer scale are yet to be demonstrated. Here, we design, fabricate and experimentally verify the smallest, first ever reported all optical nanoplasmonic XOR logic gate. The introduced XOR device is based on a novel engineerable interferometry scheme with extremely compact dimensions of λ(3)/15,500, which can be used to realize a variety of plasmonic logic functionalities. We use frequency modulated Kelvin probe microscopy to provide evidence of binary XOR functionality performed directly on SPPs with λ(3)/80,000 mode volumes. An extinction ratio of 10 dB is achieved for a device length of 150 nm, increasing up to 30 dB for a device length of 280 nm. Our findings confirm plasmonics as the favorite data carriers in integrated all optical logic devices operating on the deep nanoscale, and pave the way to the development of future ultrafast information processing technologies based on SPPs.

Audience considerations play an important role in the development of text by experienced writers but are often nonexistent in the writing of school-age children. The lack of audience awareness found in school writing may index the slow development of the social-cognitive skills necessary to conceptualize different audiences or it may result from the decontextual approach to writing that is prevalent in classrooms. This study examined the quality of students’ writing in two audience conditions: to their teacher for a term assessment and to a distant peer audience to share ideas. Seventh-grade students wrote two compositions on the same topic, one addressed to peers in other countries via a computer network and the other to their teacher for their semester grade, counterbalanced for order effects. In both conditions, there was significantly higher ratings of the papers written to communicate with peers than those written to demonstrate skill in writing. The findings suggest that the development of functional writing environments to contextualize students’ work can lead to improvements in the quality of students’ classroom writing.