arXiv subjects

Wenqing Dai

Publications and source records attributed to Wenqing Dai.

6 recordsLinked to original sources

arXiv2026

Multi-Objective RIS Deployment Optimization for Physical Layer Security in ISAC Networks

Reconfigurable Intelligent Surfaces (RIS) have emerged as a key enabler for programmable wireless environments in future Beyond-5G (B5G) and 6G networks. In the meantime, Integrated Sensing and Communication (ISAC) and Physical-Layer Security (PLS) are becoming essential functionalities for next-generation wireless systems, particularly in safety and mission-critical applications. However, jointly optimizing RIS-assisted systems to support communication, sensing, and security introduces complex and often conflicting design trade-offs. In this work, a multi-objective optimization framework for RIS-assisted networks is proposed, aiming to jointly analyze communication performance, sensing accuracy, and security-related channel properties in a unified system perspective. The proposed model jointly considers RIS deployment location, orientation, surface size, and an ISAC configuration weight that controls the allocation of RIS reflection gain between communication and sensing tasks. Simulation results reveal inherent trade-offs among communication reliability, sensing accuracy, and security performance. The proposed framework provides valuable insights into the interplay between communication, sensing, and security, and enables the design of efficient RIS deployment and configuration strategies for secure ISAC-enabled 6G wireless networks.

eess.SP↗

arXiv2024

Meta-creatures: Developing an omnipotent hydrogel cell to construct bio-inspired systems

Due to current technological challenges, including the complexity of precise control, low long-term survival and success rates, difficulty in maintaining function over extended periods, and high energy consumption, the construction of life-like creatures with multilevel structures and varied physiological characteristics is a goal that has yet to be achieved1-3. Here, to create a parallel entity termed a meta-creature with similar functions and characteristics to those of natural organisms, we introduce a process for the transformation of an omnipotent hydrogel cell (OHC), which is inspired by totipotent stem cells and carries bio-inspired bioelectricity, into a meta-creature. We captured the electrical signals transmitted between the meta-nerve fibres and rat sciatic nerves, the physicochemical signals perceived by the meta-mouth, and the information exchanged between the meta-skin and the external environment. Notably, the meta-cardiovascular system, which is capable of exchanging matter and energy with external environments, exhibited similar electrocardiogram signals during testing in rabbits; these results indicated feedback with a biological system and the potential for ex vivo bioelectric remodelling. Finally, a meta-creature was designed and exhibited bio-inspired bioelectricity signals during the simulated outdoor flight. This work reveals new possibilities for constructing bio-inspired systems, thereby improving our understanding of bioelectricity and biomimicry.

physics.chem-ph↗

arXiv2024

"Stumbling-to-Fetters" mechanism and Virginia Creeper model in hydrogel for designing bionic cardiovascular system

Manufacturing hydrogels with identical electrochemical properties are typically riddled with unresolved inquiries and challenges. Here, we utilized ultra-light graphene flakes to trace the influence of convection phenomena during reactions on hydrogels' formation and structural non-uniformity, elucidating its mechanisms. Furthermore, we confirmed that an external electric field induced the orientation of functional groups of hydrogels along the direction of this field, revealing the mechanism of its influence on the structural non-uniformity and electrochemical properties of hydrogels. Additionally, we discovered that ion diffusion was "Stumbling-to-Fetters" by the functional groups on the polymer chains within the hydrogel, unveiling this mechanism and developing the Virginia Creeper (VC) model for hydrogels. We demonstrated the scalability and application of the VC model. Furthermore, we proposed a molecular-ion diffusion and current decay equation to describe the electrochemical properties of hydrogels. As an application of the VC model, we developed a bionic cardiovascular system and proved its potential to seamlessly interface with living organisms and generate bio-like bioelectricity. Our findings provide novel insights into triboelectricity and guidance for producing hydrogels with identical electrochemical properties, and offer a new pathway for bioelectric generation and the design of new hydrogel devices.

cond-mat.soft↗

arXiv2017

Proximity-effect-induced Superconducting Gap in Topological Surface States - A Point Contact Spectroscopy Study of NbSe2/Bi2Se3 Superconductor-Topological Insulator Heterostructures

Proximity-effect-induced superconductivity was studied in epitaxial topological insulator Bi2Se3 thin films grown on superconducting NbSe2 single crystals. A point contact spectroscopy (PCS) method was used at low temperatures down to 40 mK. An induced superconducting gap in Bi2Se3 was observed in the spectra, which decreased with increasing Bi2Se3 layer thickness, consistent with the proximity effect in the bulk states of Bi2Se3 induced by NbSe2. At very low temperatures, an extra point contact feature which may correspond to a second energy gap appeared in the spectrum. For a 16 quintuple layer Bi2Se3 on NbSe2 sample, the bulk state gap value near the top surface is ~ 159 μeV, while the second gap value is ~ 120 μeV at 40 mK. The second gap value decreased with increasing Bi2Se3 layer thickness, but the ratio between the second gap and the bulk state gap remained about the same for different Bi2Se3 thicknesses. It is plausible that this is due to superconductivity in Bi2Se3 topological surface states induced through the bulk states. The two induced gaps in the PCS measurement are consistent with the three-dimensional bulk state and the two-dimensional surface state superconducting gaps observed in the angle-resolved photoemission spectroscopy (ARPES) measurement.

cond-mat.supr-con↗

arXiv2014

Momentum space imaging of Cooper pairing in a half-Dirac-gas topological superconductor (a helical 2D topological superconductor)

Superconductivity in Dirac electrons has recently been proposed as a new platform between novel concepts in high-energy and condensed matter physics. It has been proposed that supersymmetry and exotic quasiparticles, both of which remain elusive in particle physics, may be realized as emergent particles in superconducting Dirac electron systems. Using artificially fabricated topological insulator-superconductor heterostructures, we present direct spectroscopic evidence for the existence of Cooper pairing in a half Dirac gas 2D topological superconductor. Our studies reveal that superconductivity in a helical Dirac gas is distinctly different from that of in an ordinary two-dimensional superconductor while considering the spin degrees of freedom of electrons. We further show that the pairing of Dirac electrons can be suppressed by time-reversal symmetry breaking impurities removing the distinction. Our demonstration and momentum-space imaging of Cooper pairing in a half Dirac gas and its magnetic behavior taken together serve as a critically important 2D topological superconductor platform for future testing of novel fundamental physics predictions such as emergent supersymmetry and quantum criticality in topological systems.

cond-mat.supr-con↗

arXiv2014

Energy Gap Substructures in Conductance Measurements of MgB2-based Josephson Junctions: Beyond the 2-Gap Model

Several theoretical analyses of the two superconducting energy gaps of magnesium diboride, $Δ_π$ and $Δ_σ$, predict substructures within each energy gap, rather than two pure numbers. Recent experiments have revealed similar structures. We report tunneling conductance data providing additional experimental evidence for these features. The absence of these features in c-axis tunneling, and a sharp peak in the subgap (associated with the counterelectrode material), support the conclusion that these features are intrinsic to MgB2. By demonstrating the inadequacy of a simple two-gap model in fitting the data, we illustrate that some distinctions between theoretical models of energy gap substructures are experimentally accessible.

cond-mat.supr-con↗