- 标题
- 摘要
- 关键词
- 实验方案
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Real-time selection for free-space measurement device independent quantum key distribution
摘要： In consideration of the time-dependent transmittance caused by atmospheric turbulence, we combine real-time selection (RTS) method with measurement device independent quantum key distribution (MDI-QKD). The modi?ed scheme ?lters out the intervals with high channel transmittance and thus in turn increases the secure key rate. The optimal threshold of post-selection is determined by an iterative algorithm in advance, which balances the decrease in the total number of signals and the increase in average transmittance. Simulation results show that our modi?ed scheme has apparent advances in both maximum tolerant loss and secure key rate compared to the original MDI-QKD protocol. The MDI-QKD with RTS even performs better when the level of turbulence becomes larger. Furthermore, the modi?ed scheme is more stable against the statistical ?uctuation as well.
关键词： Quantum key distribution,Measurement device independent quantum key distribution,Atmospheric turbulence
更新于2025-09-04 15:30:14
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Omnidirectional sub-bandgap photo-detection using functionalized moulded composite flexible platforms
摘要： The substrate is an optically functional component of a thin film organic optoelectronic device. In the well-known context of photovoltaics, the functionality of substrate is relatively simple – that of a broadband transmittance which allows almost all the incoming light into the absorber. A less explored idea is that of incorporating other optical functionalities in the substrate bulk. Such unconventional design can help surpass the performance limitations of commonly available optoelectronic materials to achieve novel functionality. Bulk functionalization of substrates is particularly easy when the substrates are made using moldable transparent materials which allow mixing of optically functional materials into a composite substrate bulk. In this paper, the example of photonic-upconversion is considered as a representative optical function, to make organic photo-detectors which detect up-converted infrared light. By incorporating this functionality in a composite substrate two advantages are demonstrated in which the composite substrate architecture surpasses the performance of the conventional thin film device design. First, the composite substrate preserves the electronic performance of the device by spatially isolating the optical and the charge transport functions. Second, the composite architecture enables sub-bandgap photo-detection which is invariant with respect to the angle of incidence of the infrared input light, by placing the optical function before the light can encounter optically reflecting interfaces. In summary, the unconventional design employing a composite optically functional substrate can be extended to multiple optical functionalities and represents a key design finding that can enable considerably more efficient optoelectronic device designs.
关键词： Functionalization,Optoelectronic device,Moulded substrate,Composite,Up-conversion,Photodetection
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Thin Cavity-Backed Slot Antenna for Deeply Implantable Devices
摘要： Active implantable medical devices have tremendously improved the life quality and span of millions of people. Wireless power and/or information transfer between implanted and external devices bring huge benefits to patients, clinicians and researchers in terms of comfortability, mobility, implanted device performance optimisation, transferring critical physiological information for treatment, understanding desease, drug development and so on. In this context, implanted and wearable antennas are critical components for building a robust link between implanted and external devices. This paper reports on a thin cavity-backed slot wearable antenna that was designed for communication with a deeply implanted device. Apart from general requirement of antenna performance, the wearable antenna design places emphasis on ergonomics and user comfort. The fabricated thin and light weight circular cavity-backed slot antenna was assembled with a breathable foam and a flexible conductive sheet. The measured antenna bandwidth overlaps with implanted device operating frequency range. A computer model was used to estimate the path loss in tissue. The antenna was placed on the human model chest wall and the path loss to the target implantation site was calculated. The simulation results suggest that the path loss at an implantation depth of 6 cm from skin is about 25 dB.
关键词： wearable antenna,transmission characterisation,implantable device,cavity-back antenna
更新于2025-09-04 15:30:14
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Understanding Interactions between Lead Iodide Perovskite Surfaces and Lithium Polysulfide toward New-Generation Integrated Solar-Powered Lithium Battery: an ab-Initio Investigation
摘要： Energy conversion devices such as perovskite solar cells and energy storage devices such as lithium sulfur battery flourish in these decades owing to their capabilities to deliver large power conversion efficiency and store superior specific energy, with potentials to solve the global energy crisis and environmental issues. Compared with conventional energy conversion devices and energy storage devices that have limited performances, integrating the energy conversion devices and energy storage devices into a single unit is advantageous to present enhanced performance in multiple applications and satisfy the commercial needs. However, further development of the integration relies on a deeper understanding of the interactions between the functional materials in the energy conversion devices and energy storage devices. In this study, we try to bridge the gap by investigating the interactions between the light absorbing halide perovskite material CH3NH3PbI3 and the lithium polysulfide intermediates (S8, Li2S8, Li2S6, Li2S4, Li2S2 and Li2S) formed during the charging/discharging processes in lithium sulfur batteries via ab-initio calculations. We find that the CH3NH3PbI3 and lithium polysulfide species have decent interactions, with the lithium polysulfide species residing stably on the halide perovskite surfaces and such interactions are strengthened by the charge transfer characters between the adsorbates and the adsorbents. We propose that the light absorbing halide perovskite materials represented by the CH3NH3PbI3 absorber exhibit potentials to be integrated into the lithium sulfur battery cathode to serve as an anchoring material to harness the solar power and mitigate the battery degradation problem, since the dissolution of intermediate lithium polysulfide (Li2Sn) is a severe problem in lithium sulfur batteries. The resulting integrated device is superior in capturing the solar energy due to the presence of the halide perovskite moiety and exhibits a large specific energy, low cost and low toxicity due to the sulfur materials. The comprehensive understanding of the light absorbing halide perovskite material and the lithium polysulfide species in this theoretical work forms a foundation for the further development and commercialization of integrated device that captures solar energy and can be charged/discharged efficiently.
关键词： perovskite solar cells,energy storage,energy conversion,integrated device,lithium polysulfide,lithium sulfur battery,ab-initio calculations,CH3NH3PbI3
更新于2025-09-04 15:30:14
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Measurement-Device-Independent Quantum Key Distribution over asymmetric channel and unstable channel
摘要： We show that a high key rate of Measurement-Device-Independent Quantum Key Distribution (MDIQKD) over asymmetric and unstable quantum channel can be obtained by full optimization and compensation. Employing a gradient optimization method, we make the full optimization taking both the global optimization for the 12 independent parameters and the joint constraints for statistical fluctuations. We present a loss-compensation method by monitoring the channel loss for an unstable channel. The numerical simulation shows that the method can produce high key rate for both the asymmetric channel and the unstable channel. Compared with the existing results of independent constraints, our result here improves the key rate by 1 to tens of times in typical experimental conditions.
关键词： unstable channel,asymmetric channel,Quantum Key Distribution,loss-compensation method,Measurement-Device-Independent,full optimization
更新于2025-09-04 15:30:14
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Plasma Density Measurement on an SCU-PSI Device via a CO<sub>2 </sub>Dispersion Interferometer
摘要： A new CO2 dispersion interferometer (DI) was commissioned on the linear device at Sichuan University for the plasma surface interaction (SCU-PSI) [1]. The SCU-PSI device can generate a plasma pulse with very high density and a short duration. The DI system measured the plasma densities in several plasma discharges with rapid density changes. The results show a high correlation to other diagnostics such as the plasma current signal measured using a Rogowski coil. The line-density resolution of the system is 6.3 × 1017/m2. The time resolution is 0.05 ms.
关键词： dispersion interferometer,interferometer,linear device,pulse discharge,photoelastic modulator
更新于2025-09-04 15:30:14
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Tunable Liquid Crystal Based Phase Shifter with a Slot Unit Cell for Reconfigurable Reflectarrays in F-Band
摘要： An electrically tuned phase shifter based on the single slot unit cell and liquid crystal for a reconfigurable reflectarray antenna was presented. The simulation and measured results obtained at the F-band were used to demonstrate that the dielectric properties of a nematic state liquid crystal could be exploited to realize a slot unit cell phase shifter for the reconfigurable reflectarrays antennas. By reducing the inhomogeneous of the external electric field in the liquid crystal layer, a lower control voltage and improved model accuracy was obtained. In the experiments test, the achieved saturation bias voltage (10 V) was smaller than the previously reported structure, and the phase shift of the reflectarray greater than 300? was achieved in the frequency range 121.5–126 GHz. The maximum phase shift of 306? occurred at 124.5 GHz.
关键词： phase shifter,phase control,liquid crystal device,reconfigurable reflectarray
更新于2025-09-04 15:30:14
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Micro-fabricated wideband band-stop filter using GaAs-based integrated passive device technology
摘要： This paper presents a new concept of implementing a micro-fabricated wideband band-stop filter on a gallium arsenide (GaAs) substrate using integrated passive device technology. The incorporation of an air-bridge structure was explored to enhance design flexibility and achieve excellent radio-frequency performance of the filter. A wideband band-stop filter was realized on a GaAs substrate, generating an insertion loss of ? 0.37 dB and a return loss of ? 38 dB with excellent attenuation of ? 28.78 and ? 22.27 dB, in the lower and the upper passband, respectively. The filter resonates at 10.72 GHz, occupying a die area of 2000 μm × 1540 μm. The selectivity of the filter is reflected by its tremendous suppression of out-of-band signals with the existence of attenuation poles in the vicinity of the resonance frequency. Experimental verification of the filter response demonstrates its potential use as an on-chip device operating in the X-band frequency spectrum.
关键词： Gallium arsenide (GaAs),Wideband band-stop filter,Radio frequency (RF),Integrated passive device technology,Micro-fabrication
更新于2025-09-04 15:30:14
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Charge transport layers manage mobility and Carrier density balance in light-emitting layers influencing the operational stability of organic light emitting diodes
摘要： Organic light emitting diodes (OLEDs) consist of several organic layers, including the charge injection layer, charge transport layer, and light emitting layer (EML). Of these layers, the charge transport layer is crucial for ensuring device longevity, but its overall effects on charge transport and corresponding device stability are poorly understood. Herein we report the factors influencing differences in lifetime between two OLEDs with different hole transporting layers (HTLs). Comprehensive electrical analysis of the materials and the devices reveals that the mobility, accumulation, trapping, and the transport path of holes in the EML are totally changed by the HTLs. The charge transport layers affect mobility and carrier density balance in the EML through the modification of the charge transport path and the energetic barrier. This results in a reduction of overbalanced polaron density, which is critical for bond dissociation in excitonic interactions. Consequently, device lifetime is increased sevenfold through modification of the HTL structure without any alteration of the EML. These results imply that the analysis of polaronic transport through impedance spectroscopy is a crucial step in determining the requisite electrical properties for charge transport layers, with a view to maximizing the operational stability of OLEDs.
关键词： charge transport,Organic light-emitting diodes,device stability,impedance spectroscopy
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE 6th Workshop on Wide Bandgap Power Devices and Applications (WiPDA) - Atlanta, GA, USA (2018.10.31-2018.11.2)] 2018 IEEE 6th Workshop on Wide Bandgap Power Devices and Applications (WiPDA) - Instabilities by Parasitic Substrate-Loop of GaN-on-Si HEMTs in Half-Bridges
摘要： The stability of GaN-on-Si HEMTs with substrate-to-source termination is analyzed in a high-voltage half-bridge. The work exposes that external substrate termination creates a parasitic substrate loop, which leads to unstable switching behavior under certain conditions. Stability analysis reveals that parasitic inductance in the substrate-loop alone is sufficient for instabilities, even with zero parasitic inductance in the gate- and power-loops. A systematic analytical stability analysis is carried out based on a small-signal equivalent circuit. The theory is verified by measurements using a PCB-embedded 600 V GaN HEMT with integrated gate driver. Adequate damping of the substrate loop resonance enables stable operation of the half-bridge module.
关键词： Semiconductor Device Packaging,Gallium Nitride,Switching Circuits,Circuit Stability,Substrate Potential,Bridge Circuits
更新于2025-09-04 15:30:14