Quantum Computing for MIMO Beam Selection Problem: Model and Optical Experimental Solution

Massive multiple-input multiple-output (MIMO) has gained widespread popularity in recent years due to its ability to increase data rates, improve signal quality, and provide better coverage in challenging environments. In this paper, we investigate the MIMO beam selection (MBS) problem, which is proven to be NP-hard and computationally intractable. To deal with this problem, quantum computing that can provide faster and more efficient solutions to large-scale combinatorial optimization is considered. MBS is formulated in a quadratic unbounded binary optimization form and solved with Coherent Ising Machine (CIM) physical machine. We compare the performance of our solution with two classic heuristics, simulated annealing and Tabu search. The results demonstrate an average performance improvement by a factor of 261.23 and 20.6, respectively, which shows that CIM-based solution performs significantly better in terms of selecting the optimal subset of beams. This work shows great promise for practical 5G operation and promotes the application of quantum computing in solving computationally hard problems in communication.Comment: Accepted by IEEE Globecom 202

Highly enhanced thermoelectric and mechanical performance of copper sulfides via natural mineral in-situ phase separation

In situ phase separation precipitates play an important role in enhancing the thermoelectric properties of copper sulfides by suppressing phonon transmission. In this study, Cu1.8S composites were fabricated by melting reactions and spark plasma sintering. The complex structures, namely, micron-PbS, Sb2S3, nano-FeS, and multiscale pores, originate from the introduction of FePb4Sb6S14 into the Cu1.8S matrix. Using effective element (Fe) doping and multiscale precipitates, the Cu1.8S+0.5 wt% FePb4Sb6S14 bulk composite reached a high dimensionless figure of merit (ZT) value of 1.1 at 773 K. Furthermore, the modulus obtained for this sample was approximately 40.27 GPa, which was higher than that of the pristine sample. This study provides a novel strategy for realizing heterovalent doping while forming various precipitates via in situ phase separation by natural minerals, which has been proven to be effective in improving the thermoelectric and mechanical performance of copper sulfides and is worth promoting in other thermoelectric systems

Chitosan-Based Self-Healing Hydrogel: From Fabrication to Biomedical Application

Biocompatible self-healing hydrogels are new-generation smart soft materials that hold great promise in biomedical fields. Chitosan-based self-healing hydrogels, mainly prepared via dynamic imine bonds, have attracted broad attention due to their mild preparation conditions, excellent biocompatibility, and self-recovery ability under a physiological environment. In this review, we present a comprehensive overview of the design and fabrication of chitosan-based self-healing hydrogels, and summarize their biomedical applications in tissue regeneration, customized drug delivery, smart biosensors, and three/four dimensional (3D/4D) printing. Finally, we will discuss the challenges and future perspectives for the development of chitosan-based self-healing hydrogels in the biomedical field