Aditya Kulkarni — Page 2

arXiv2020

Generating Synthetic Multispectral Satellite Imagery from Sentinel-2

Multi-spectral satellite imagery provides valuable data at global scale for many environmental and socio-economic applications. Building supervised machine learning models based on these imagery, however, may require ground reference labels which are not available at global scale. Here, we propose a generative model to produce multi-resolution multi-spectral imagery based on Sentinel-2 data. The resulting synthetic images are indistinguishable from real ones by humans. This technique paves the road for future work to generate labeled synthetic imagery that can be used for data augmentation in data scarce regions and applications.

cs.CV↗

arXiv2019

Explaining Observed Stability of Excitons in Highly Excited CdSe Nanoplatelets

Two-dimensional electron-hole gases in colloidal semiconductors have a wide variety of applications. Therefore, a proper physical understanding of these materials is of great importance. In this paper we present a detailed theoretical analysis of the recent experimental results by Tomar et al., that show an unexpected stability of excitons in CdSe nanoplatelets at high photoexcitation densities. Including the screening effects by free charges on the exciton properties, our analysis shows that CdSe nanoplatelets behave very differently from bulk CdSe, and in particular do not show a crossover to an electron-hole plasma in the density range studied experimentally, even though there is substantial overlap between the excitons at the highest densities achieved. From our results we also conclude that a quantum degenerate exciton gas is realized in the experiments, which opens the prospect of observing superfluidity in CdSe nanoplatelets in the near future.

cond-mat.mes-hall↗