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Charge noise analysis of metal oxide semiconductor dual-gate Si/SiGe quantum point contacts
摘要： The frequency dependence of conductance noise through a gate-defined quantum point contact fabricated on a Si/SiGe modulation doped wafer is characterized. The 1/f2 noise, which is characteristic of random telegraph noise, is reduced by application of a negative bias on the global top gate to reduce the local gate voltage. Direct leakage from the large global gate voltage also causes random telegraph noise, and therefore, there is a suitable point to operate quantum dot measurement.
关键词： quantum point contacts,global top gate,charge noise,Si/SiGe,random telegraph noise
更新于2025-09-23 15:21:21
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SparseCast: Hybrid Digital-Analog Wireless Image Transmission Exploiting Frequency Domain Sparsity
摘要： A hybrid digital-analog wireless image transmission scheme, called SparseCast, is introduced, which provides graceful degradation with channel quality. SparseCast achieves improved end-to-end reconstruction quality while reducing the bandwidth requirement by exploiting frequency domain sparsity through compressed sensing. The proposed algorithm produces a linear relationship between the channel signal-to-noise ratio (CSNR) and peak signal-to-noise ratio (PSNR), without requiring the channel state knowledge at the transmitter. This is particularly attractive when transmitting to multiple receivers or over unknown time-varying channels, as the receiver PSNR depends on the experienced channel quality, and is not bottlenecked by the worst channel. SparseCast is benchmarked against two alternative algorithms: SoftCast and BCS-SPL. Our findings show that the proposed algorithm outperforms SoftCast by approximately 3.1 dB and BCS-SPL by 14.8 dB.
关键词： hybrid digital-analog,compressed sensing,channel signal-to-noise ratio,frequency domain sparsity,peak signal-to-noise ratio,wireless image transmission
更新于2025-09-23 15:21:21
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Evaluation method for the performance of light screen array measurement system based on semi-physical simulation
摘要： The paper presents a method to evaluate the performance of light screen array measurement system (LSA for short) objectively and scienti?cally. We put forward the scheme of semi-physical veri?cation platform based on arbitrary waveform generator (AWG), and this instrument is used as a substitute for light screen detector in the LSA. according to some main characteristics of dynamic signal, the waveform ?les of two simulation signals with a certain time interval are compiled and created through con?guring some options through a signal waveform edition software. Furthermore, these waveform ?les are downloaded into the AWG to generate two channel simulation signals. Then, the time interval of these two signals can be measured in the signal acquisition & processing module of LSA. Finally, we can compare the di?erence between true values and measured results. Through experiment and analysis, the proposed method can meet the requirement of performance evaluation on the LSA, and it is superior to the other previous methods.
关键词： Semi-physical simulation,Noise environment,Waveform modeling and editing,Photoelectric measurement,Dynamic signal generation
更新于2025-09-23 15:21:21
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Improving the Secret Key Rate of Coherent Quantum Key Distribution with Bayesian Inference
摘要： Laser phase noise is one of the major limitations in continuous-variable quantum key distribution, when the local oscillator is placed at the receiver site. Thus, improving phase noise mitigation can improve the secret key rate. This paper provides an experimental investigation of different Bayesian methods for that purpose. It is shown that, compared to a previously reported method, the excess noise power can be reduced by about 15%. In some scenarios, this can improve the secret key rate by a factor of 9.
关键词： phase noise,Bayes procedures,quantum communications
更新于2025-09-23 15:21:21
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Novel OSNR Measurement Techniques Based on Optical Spectrum Analysis and their Application to Coherent-Detection Systems
摘要： We discuss and review in-service Optical-Signal-to-Noise-Ratio measurement techniques with a focus on methods relying on optical spectrum analysis. We briefly review the OSNR definition and the measurement procedure employed in early multi-wavelength systems with in-line amplification, and present in detail the development of the spectrum-based OSNR measurement methods to account for polarized, filtered DWDM signals, and further still, to the current generation of DWDM systems based on coherent detection. We present mathematical implementations for the measurement of polarized signals and their evolution to a reference-based method, suitable for measuring polarization-multiplexed signals independent of coherent transmission formats and receiver metrics. The performance of this reference-based technique is illustrated in a wide range of coherent transmission use cases, thus demonstrating its tolerance to fiber non-linearity induced spectral deformation of the signal. We also explain and demonstrate the ability of this technique to discriminate the amplified spontaneous emission noise due to in-line amplifiers from “Gaussian-like” noise generated in a non-linear operating regime. Finally, we present an extension of this OSNR measurement technique for links where in-line filtering causes significant spectral deformations of the signal and we show how it can be applied to troubleshooting and maintenance-monitoring use cases. The OSNR measurement statistics across all test conditions indicate accuracy levels suitable for use in deployed DWDM networks with ROADMs and coherent transponders.
关键词： signal to noise ratio,optical receivers,optical fiber testing,Optical fiber communication
更新于2025-09-23 15:21:21
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ROBUST ADAPTIVE WIDEBAND BEAMFORMING USING PROBABILITY-CONSTRAINED OPTIMIZATION
摘要： The existing robust narrowband beamformers based on probability-constrained optimization have an excellent performance as compared to several state-of-the-art robust beamforming algorithms. However, they always assume that the steering vector errors are small enough. Without this assumption, we extend the probability-constrained approach to a wideband beamformer. In addition, a novel robust wideband beamformer with frequency invariance constraints is proposed by introducing the response variation (RV) element. Our problems can be reformulated in a convex form as the iterative second order cone programming (SOCP) problem and solved effectively using well-established interior point method. Compared with existing robust wideband beamformers, a more efficient control over the beamformer’s response against the steering vector errors is achieved with an improved output signal-to-interference-plus-noise ratio (SINR).
关键词： response variation (RV),robust adaptive wideband beamforming,frequency invariance constraints,second order cone programming (SOCP),probability-constrained optimization,signal-to-interference-plus-noise ratio (SINR)
更新于2025-09-23 15:21:21
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Speckle Noise Reduction of Time Series Sar Images Based on Wavelet Transform and Kalman Filter
摘要： Synthetic Aperture Radar (SAR) imaging systems can provide valuable sources of earth observation data for various applications. Speckle noise reduction of images produced by these systems is a challenging issue. In this paper, a novel method is proposed for reducing the speckle noise from time series SAR images. This method is mainly based on wavelet transform and Kalman filter. The proposed method is applied to a time series SAR images acquired by Sentinel-1 over Tehran, Iran. To demonstrate the performance of the proposed method, both qualitative and quantitative evaluations are reported compared to those of conventional speckle filtering methods. The experimental results show the good performance and efficiency of the proposed method for the speckle reduction of multitemporal SAR images. As well, the results show that the proposed method can preserve the major edge structures and the spatial resolution while reducing the time of processing.
关键词： wavelet transform,speckle noise reduction,kalman filter,Time series SAR images
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Field emission current investigation of p-type and metallized silicon emitters in the frequency domain
摘要： We investigated two different field emitter arrays consisting of 10×10 p-type and 10×10 undoped Au-coated high aspect ratio silicon tips. The I-V characterization of the p-type sample showed a pronounced saturation for voltages higher than 500 V and a maximum emission current of 39 nA. The metallized sample revealed a FN-like emission up to several μA. The metallized and the p-type sample operating below the saturation region showed high current fluctuations of ±16%. Whereas, the metallized sample with current regulation and the p-type sample in the saturation yielded a current stability of ±0.4% and ±0.3%, respectively. Investigations in the frequency domain revealed the for field emission typical 1/f-noise. By operating in the saturation region (p-type sample) or using an emission current regulation (metallized sample) the noise level was reduced by at least 20 dB. Finally, the p-type sample was illuminated by a light emitting diode to increase and modulate the emission current in the saturation region. The emission current was increased by a factor of 3.7 to 145 nA. With this configuration we emulated an unstable emission behavior and evaluated the performance of our emission current regulation circuit.
关键词： field emitter array,current stability,current fluctuation,field emission noise,field emission,silicon tip
更新于2025-09-23 15:21:21
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[IEEE 2018 33rd Symposium on Microelectronics Technology and Devices (SBMicro) - Bento Gon?alves, Brazil (2018.8.27-2018.8.31)] 2018 33rd Symposium on Microelectronics Technology and Devices (SBMicro) - Low-Frequency Noise Investigation in Long-Channel Fully Depleted Inversion Mode n-type SOI Nanowire
摘要： This work presents a Low-Frequency Noise (LFN) investigation in fully depleted n-type Silicon-On-Insulator (SOI) nanowire transistors working in linear region with VDS=50mV. Long-channel devices of 1μm and 10μm are evaluated. A wide range of fin width is considered in the LFN analysis, from 15nm up to 105nm. The results showed a flicker noise (1/fγ) behavior with gate voltage and a decrease of normalized noise SID/IDS overdrive increase for frequencies bellow 500Hz. Above this frequency, that generation and recombination noise with 1/f2 decay overlaps the flicker noise, becoming the predominant noise source. The cut-off frequency increases with gate voltage overdrive while the gamma exponent decreases. Gamma reduces from 1.3 to 0.9 and from 0.95 to 0.65 for devices with channel length of 1μm and 10μm, respectively. A major noise variation of about one order of magnitude with gate voltage overdrive increase was observed in devices of 1μm long in comparison to channel length of 10μm. The devices showed weak noise dependence on fin width due to mobility decrease as nanowires become narrower.
关键词： fully depleted SOI,low-frequency noise,nanowire
更新于2025-09-23 15:21:21
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Robust Harmonic Retrieval via Block Successive Upper-Bound Minimization
摘要： Harmonic retrieval (HR) is a problem of significance with numerous applications. Many existing algorithms are explicitly or implicitly developed under Gaussian noise assumption, which, however, are not robust against non-Gaussian noise such as impulsive noise or outliers. In this paper, by employing the (cid:2)p-fitting criterion and block successive upper-bound minimization (BSUM) technique, a variant of the classical RELAX algorithm named as BSUM-RELAX is devised for robust HR. It is revealed that the BSUM-RELAX successively performs alternating optimization along coordinate directions, i.e., it updates one harmonic by fixing the other (K ? 1) components, such that the whole problem is split into K single-tone HR problems, which are then solved by creating a surrogate function that majorizes the objective function of each subproblem. To further refine the frequency component, the Newton’s method that takes linear complexity O(N ) is derived for updating the frequency estimates. We prove that under the single-tone case, BSUM-RELAX converges to a Karush-Kuhn-Tucker point. Furthermore, the BSUM-RELAX is extended to the multidimensional HR case. Numerical results show that the proposed algorithm outperforms the state-of-the-art methods in heavy-tailed noise scenarios.
关键词： robust estimation,impulsive noise/outliers,Harmonic retrieval,RELAX,majorization minimization
更新于2025-09-23 15:21:21