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Gaussian random number generator: Implemented in FPGA for quantum key distribution
摘要： Quantum key distribution is the process of using quantum communication to establish a shared key between two parties. It has been demonstrated the unconditional security and effective communication of quantum communication system can be guaranteed by an excellent Gaussian random number (GRN) generator with high speed and an extended random period. In this paper, we propose to construct the Gaussian random number generator by using field‐programmable gate array (FPGA), which is able to process large data in high speed. We also compare three algorithms of GRN generation: Box‐Muller algorithm, polarization decision algorithm, and central limit algorithm. We demonstrate that the polarization decision algorithm implemented in FPGA requires less computing resources and also produces a high‐quality GRN through the null hypothesis test.
关键词： field‐programmable gate array,numerical modeling,quantum key distribution,Gaussian random numbers
更新于2025-09-19 17:15:36
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Longer distance continuous variable quantum key distribution protocol with photon subtraction at the receiver
摘要： One of the limitations of continuous variable quantum key distribution is the relatively short transmission distance of secure keys. Some solutions have been proposed to overcome the limitation including reverse reconciliation, trusted noise concept, and non-Gaussian operation. In this paper, we propose a protocol using photon subtraction at the receiver, which combines the synergetic benefits of the aforementioned approaches. Using simulations, we show that the performance of the proposed protocol outperforms other conventional protocols. The results showed that an improvement in secure key distance can be obtained using a non-Gaussian operation, depending on the position where the operation is performed, similar to the trusted noise concept. Furthermore, the result implies existence of some Gaussian operations which increases security without using a beam splitter.
关键词： Continuous variable quantum key distribution,Quantum cryptography,Quantum information and processing,Non-Gaussian state
更新于2025-09-19 17:15:36
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Deep Gaussian Processes for Geophysical Parameter Retrieval
摘要： This paper introduces deep Gaussian processes (DGPs) for geo-physical parameter retrieval. Unlike the standard full GP model, the DGP accounts for complicated (modular, hierarchical) processes, provides an efficient solution that scales well to large datasets, and improves prediction accuracy over standard full and sparse GP models. We give empirical evidence of performance for estimation of surface dew point temperature from infrared sounding data.
关键词： Deep Gaussian Processes,IASI,surface dew point temperature,Model inversion,statistical retrieval,infrared sounding
更新于2025-09-19 17:15:36
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[Methods in Molecular Biology] Immunological Tolerance Volume 1899 (Methods and Protocols) || Analysis of Denoising Filters for Source Identification Using PRNU Features
摘要： In Digital Image Forensics, one of the important techniques is Source Camera Identification (SCI) that attempts to identify the source camera of captured images. The sensor patterns of captured images are used for identification. The most regular pattern noise is photo response non-uniformity (PRNU) that can be generated by sensor defects during manufacturing process. These noises are distinguishable due to different sensor vendors of devices. In this work, identification is based on mobile camera that is from which mobile model a given image is captured. Here the analysis of three different denoising filters (Wiener, Total Variation and Gaussian) are done, to get the best result in our dataset. For classification, support vector machine (SVM) classifier is used and validation is done using 10-fold cross-validation technique.
关键词： Gaussian,Photo Response non-Uniformity,Wiener,Total variation
更新于2025-09-19 17:15:36
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Means and covariances of photon numbers in multimode Gaussian states
摘要： In the field of continuous variables and particularly of Gaussian states an important role is played by the statistics of photon numbers. This issue has been considered in pioneering works for the one- and two-mode cases, but a systematic approach seems not to be available. In this paper, the most general multimode mixed Gaussian state, which is generated starting from a multimode thermal state and processed by the most general Gaussian unitary, is considered. In the N-mode the photon numbers are represented by N random variables, one for each mode, and the target is the evaluation of the means and of the covariances. The means describe statistically the amount of photon numbers in each mode, while the covariances give the correlations between the photon numbers in the different modes. For both means and covariances a closed-form result is obtained, expressed in simple and compact formulas. The main tools are provided by the representation of Gaussian unitaries (given by a cascade of an N-mode squeeze operator, an N-mode rotation operator, and a parallel set of N single-mode displacement operators) and by the corresponding Bogoliubov transformations.
关键词： means,photon numbers,multimode,covariances,Bogoliubov transformations,Gaussian states
更新于2025-09-19 17:15:36
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Internal electromagnetic waves, energy trapping, and energy release in simple time-domain simulations of single particle scattering.
摘要： During the decay phase of the interaction of a femto-second Gaussian pulse with a single spherical particle, the presence of quasi-periodic short oscillatory bursts of electromagnetic energy at points in the near field outside the particle have been observed in three-dimensional simulations. Analogous behavior can be very easy produced and understood in simple one-dimensional scattering calculations. In two dimensions the situation immediately becomes more complicated and interesting. Here we discuss results from two-dimensional pseudo-spectral time-domain simulations of scattering from circular, elliptical, and hexagonal particles with the real index of refraction m=1.3. Our focus is on how energy initially trapped within a particle after interaction with an incident Gaussian pulse is released over time, and we show two kinds of events that can result in 'bursts' of energy release from the particles: (i) the coalescence of counter-propagating wave-packet-like electromagnetic field structures that have maximum amplitude near the surface of the particle, and (ii) encounters of individual packets with surface regions of high curvature. The coalescence events in the circular case show the dynamical origin of a two-dimensional form of 'photonic nanojet.' The two-dimensional simulations make clear the reason for quasi-periodic intermittent bursts at fixed near-field points outside the particle. Examination of field evolution shows that distinct near-surface internal field maxima, ostensibly the 'source' of the emission bursts, are in fact inter-connected by caustic-like internal field structures that extend throughout the particle and have complex time evolution. The revealed intricacy of these connections suggests that understanding the origins of pulsed emissions in three dimensions, even for simple particle geometries, may be quite challenging.
关键词： caustic evolution,photonic nanojet,single particle scattering,femtosecond Gaussian pulses,internal electromagnetic waves
更新于2025-09-19 17:15:36
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Enhanced second harmonic generation of Hermitea??Gaussian laser beam in plasma having density transition
摘要： Under the combined effect of relativistic and ponderomotive nonlinearity, resonant second harmonic generation of an intense Hermite–Gaussian (H–Gaussian) laser beam in a plasma having upward density ramp profile has been theoretically investigated. Under WKB approximation and with the use of the moment theory approach the coupled differential equations are derived which govern the spot size of the H–Gaussian laser beam. The ponderomotive force creates the density gradient in the background plasma electrons which is responsible for the excitation of the electron plasma wave. The large-amplitude electron plasma wave interacts with the fundamental beam which produces coherent radiations with double the frequency of the incident beam. In addition, the Gouy phase shift is observed for the H–Gaussian laser beam in plasma under the effect of density transition. The analysis shows the vital role of the different modes of the H–Gaussian laser beam and density ramp on the efficiency of generated harmonics and self-phase shift of laser beams in plasma.
关键词： ponderomotive,density ramp,second harmonic generation,relativistic nonlinearity,Hermite–Gaussian laser beam
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE Innovative Smart Grid Technologies - Asia (ISGT Asia) - Chengdu, China (2019.5.21-2019.5.24)] 2019 IEEE Innovative Smart Grid Technologies - Asia (ISGT Asia) - Designs and Applications for the Controller Parameters of the Photovoltaic System
摘要： Many economically important minerals have absorption features in the short-wave infrared (SWIR; 2000–2500 nm). Sensors which measure this part of the spectrum cannot detect the wavelength minimum of a feature at ～900 nm (F900), indicative of ferric iron mineralogy. A method based on Gaussian processes (GPs) was developed and compared with multiple linear regression (MLR) to estimate the wavelength position of F900 from SWIR data (1002–1355 nm). SWIR data with different signal-to-noise ratios were acquired from crushed rock samples by a nonimaging spectrometer and an imaging spectrometer. GP estimates of wavelength position were converted to the proportion of goethite using coefficients from a regression of the proportion of goethite determined from X-ray diffraction (XRD) on wavelength position measured directly from spectra. GP-estimated wavelength positions were within the 2-nm and ～4-nm root-mean-square error of measurements made directly from spectra for nonimaging and imaging spectrometer data, respectively. Proportions of goethite derived from these estimates were respectively within 4% and 6% of the values measured by XRD. MLR performed poorly compared to GPs when applied to data with no added noise and failed when applied to data with added noise or to imaging spectrometer data. These findings indicate that the wavelength position of F900—an indicator of ferric iron mineralogy—can be estimated from data acquired at SWIR wavelengths (1002–1355 nm). This opens up possibilities for using a single (SWIR) sensor to acquire information on ferric iron mineralogy (using F900) and other minerals with diagnostic absorptions between 1000 and 2500 nm.
关键词： geology,infrared spectroscopy,iron,image sensors,remote sensing,Gaussian processes (GPs),mining industry,Electromagnetic radiation,spectral analysis,signal processing
更新于2025-09-19 17:13:59
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Terahertz radiation from multi ion plasma irradiated by two cross focused Gaussian laser beams
摘要： Terahertz (THz) radiation generation by nonlinear coupling of two color Gaussian laser beams in a plasma with multi-ion species is numerically investigated by taking into account the nonlinearity due to ponderomotive force and space-charge field. By calculating the modification of electron density distribution of such plasma, coupled differential equations governing the evolution of two laser beams’ spot size and the outcome THz wave amplitude are established. The influence of the ionic species density and charge composition on the cross focusing of laser beams as well as generation of THz radiation is studied. The results mainly demonstrated that nonlinear effects in a multiply ionized plasma are excited stronger in comparison to the singly ionized one. It was found that the presence of ion species of higher charge enhances the cross focusing of beams and, consequently, THz field amplitude. The generated THz emission also strongly depends on the density of ionic species. The results showed that the minimum output of THz radiation is related to the higher density of singly charged ionic species. Moreover, it was found that the maximum value of THz amplitude takes place within a specific range of laser intensities.
关键词： multi-ion plasma,ponderomotive force,space-charge field,Terahertz radiation,Gaussian laser beams
更新于2025-09-19 17:13:59
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OFDM tolerance to additive white Gaussian and laser phase noises in optical heterodyning systems accompanied by the feasible pilot-assisted equalization
摘要： It is well known that the performance of orthogonal frequency division multiplexing (OFDM) is limited by phase noise, which depends on the laser linewidths for coherent-detection radio over fiber (RoF) systems. In this manuscript, we present numerical and theoretical results to analyze the combined effects of phase and additive white Gaussian noises in the performance of RoF-OFDM schemes with the feasible pilot-based channel corrector. This phase-noise compensator is adopted due to its effectiveness as well as simplicity. It is shown that as the subcarrier modulation format increases, the required radio frequency linewidth for overcoming the FEC limit decreases by a factor of 10 times. Also, there is a signal–noise ratio penalty of 7 dB. Furthermore, it is demonstrated that the bit error rate enhances as the product of the laser linewidths and OFDM symbol period decreases because the pilot-assisted equalization method acts as a high-pass filter for phase noise. We finally discovered that the intermediate-frequency (IF) carrier suppression is not mandatory; the system performance is not affected by selecting properly the carrier–signal ratio and IF. To confirm the previous observation, a novel way to measure phase noise in RoF-OFDM signals accompanied by the IF carrier is proposed. The mean integral phase noise comes from the adaptation of the root mean square phase deviation of the single-carrier systems. This work serves as a guideline for the study and design of OFDM-based RoF schemes susceptible to direct and coherent detections.
关键词： Laser phase noise,Additive white Gaussian noise,Intermediate frequency suppression,Orthogonal frequency division multiplexing,Radio over fiber systems
更新于2025-09-19 17:13:59