Quantum advantages for image filtering on images with efficient encoding and lower-bounded signal-to-noise ratio

Quantum image processing has long been a fascinating field,but establishing the existence of quantum speedup for all images remains challenging.In this study,we aim to identify a subset of images for which a quantum algorithm can be developed with a guaranteed advantage.Specifically,we present a quantum image filtering algorithm that exhibits an exponential speedup for efficiently encoded images with a lower-bounded signal-to-noise ratio.Our approach relies on a fixed-point Grover's search to emulate the effect of Hadamard multiplication with the filtering function.To demonstrate its effectiveness,we apply our method to three typical filtering problems.Additionally,we emphasize the significance of the efficient-encoding assumption by illustrating that the quantum speedup may diminish for images lacking efficient encoding.Our work underscores the importance of exploring image types and features to realize potential quantum advantages in image processing.

Colloidal quantum dots and two-dimensional material heterostructures for photodetector applications

Photodetectors(PDs)are optoelectronic devices that convert optical signals into electrical responses.Recently,there has been a tremendous increase in research interest in PDs based on colloidal quantum dots(QDs)and two-dimensional(2D)material heterostructures owing to the strong light-absorption capacity and the well-adjustable band gap of QDs and the superior charge carriers transfer ability of 2D materials.In particular,the heterojunction formed between QDs and 2D materials can effectively enhance the separation and transport of photogenerated charge carriers,which is expected to establish PDs with ultrahigh photoconductive gain,high responsivity,and detectivity.This review aimed to summarize the state-of-the-art advances in the research of QDs/2D material nanohybrid PDs,including the device parameters,archi-tectures,working mechanisms,and fabrication technologies.The prog-ress of hybrid PDs based on the heterojunction of QDs with different 2D materials,along with their innovative applications,are comprehensively described.In the end,the challenges and feasible strategies in future research and development are briefly proposed.