Quantum key distribution provides secure keys resistant to code-breaking quantum computers. The continuous-variable version of offers the advantages higher secret rates in metropolitan areas, as well use standard telecom components that can operate at room temperature. However, transmission distance these systems (compared with discrete-variable systems) are currently limited and considered unsuitable for long-distance distribution. Herein, we report experimental results long over 202.81 km...

A high-speed Gaussian-modulated continuous-variable quantum key distribution (CVQKD) with a local oscillator (LLO) is experimentally demonstrated based on pilot-tone-assisted phase compensation. In the proposed scheme, frequency-multiplexing and polarization-multiplexing techniques are used for separate transmission heterodyne detection between signal pilot tone, guaranteeing no crosstalk from strong tone to weak different requirements of low-noise high-saturation limitation tone. Moreover,...

A high-rate continuous-variable quantum key distribution (CV-QKD) system based on high-order discrete modulation is experimentally investigated. With the help of novel scheme, effective digital signal processing (DSP) algorithms and advanced analytical security proof methods, transmission results 5.059 km, 10.314 24.490 50.592 km are achieved for 1 GBaud optimized signals. Correspondingly, asymptotic secret rates (SKRs) 292.185 Mbps, 156.246 50.491 7.495 Mbps Gaussian (DG) 64QAM, 328.297...

Precise and secure time synchronization between two remote sites is necessary in many practical scenarios. Recently, the two-way fiber transfer (TWFTT) system has become an attractive option for high-precision synchronization. However, TWFTT implemented based on symmetric link assumption, such assumption may be maliciously utilized to cause significant asynchronization TWFTT. In this paper, we propose novel controllable asymmetry attack schemes TWFTT, namely, attenuation attack. We...

Abstract Continuous-variable quantum key distribution (CVQKD) has potential advantages of high secret rate, which is very suitable for high-speed metropolitan network application. However, the rates reported CVQKD systems are only a few Mbps over typical transmission distance so far. Here, we address fundamental experimental problems and demonstrate single-carrier four-state with sub-Gbps rate within area. In demonstrated using local oscillator, an ultra-low level excess noise obtained...

Optical chaos generated by perturbing semiconductor lasers has been viewed, over recent decades, as an excellent entropy source for fast physical random bit generation (RBG) owing to its high bandwidth and large fluctuations. However, most optical-chaos-based generators perform their quantization process in the electrical domain using analog-to-digital converters, so real-time rates a single channel are severely limited at level of Gb/s due electronic bottleneck. Here, we propose...

We experimentally demonstrated a sub-Mbps key rate Gaussian-modulated coherent-state (GMCS) continuous-variable quantum distribution (CV-QKD) over 100-km transmission distance. To efficiently control the excess noise, signal and pilot tone are co-transmitted in fiber channel based on wideband frequency polarization multiplexing methods. Furthermore, high-accuracy data-assisted time domain equalization algorithm is carefully designed to compensate phase noise variation low signal-to-noise...

Photon subtraction can enhance the performance of continuous-variable quantum key distribution (CV QKD). However, enhancement effect will be reduced by imperfections practical devices, especially limited efficiency a single-photon detector. In this paper, we propose non-Gaussian postselection method to emulate photon substraction used in coherent-state CV QKD protocols. The virtual not only avoid complexity and photon-subtraction operation, which extends secure transmission distance as ideal...

As a fundamental phenomenon in nature, randomness has wide range of applications the fields science and engineering. Among different types random number generators (RNG), quantum generator (QRNG) is kind promising RNG as it can provide provable true numbers based on inherent processes. Nevertheless, from QRNG be diminished (or even destroyed) if devices (especially entropy source devices) are not perfect or ill-characterized. To eliminate practical security loopholes source,...

The method of improving the performance continuous-variable quantum key distribution protocols by postselection has been recently proposed and verified. In measurement-device-independent (CV-MDI QKD) protocols, measurement results are obtained from untrusted third party Charlie. There is still not an effective CV-MDI QKD with measurement. We propose a to improve coherent-state protocol virtual photon subtraction via non-Gaussian postselection. transmitted data equivalent ideal on two-mode...

Rapidly switching semiconductors in modern high power inverter/motor-drive systems generate fast changing voltages and currents which may result unwanted emissions. While models of inverters have been built the past to predict emissions, they are typically "black box" where cause solution emissions problems is difficult analyze. To improve inverter system design strategies, a detailed measurement-based SPICE model was there straightforward correlation between geometry parasitic circuit...

We demonstrate experimentally that flat and broadband chaotic signals can be easily generated by combining a multi-mode laser diode subject to optical feedback with band-pass filter. Measurements are made of the RF spectra single-mode outputs from an external cavity Fabry-Perot (FP) semiconductor before after filtering procedure. In this way it is found in chaos regime low-frequency energy output enhanced about 25 dB comparing output. Moreover, associated 3-dB bandwidth reach around 6 GHz...

Quantum key distribution, which ensures information-theoretically secret generation, is currently advancing through photonic integration to achieve high performance, cost reduction, and compact size, thereby facilitating the large-scale deployment. Continuous-variable quantum distribution an attractive approach for integrations due its compatibility with off-the-shelf optical communication devices. However, chip-based systems have encountered significant limitations primarily related...

Academic achievement reflects students' learning outcomes over a period of time and serves as crucial gauge student levels, well focal point societal interest. To investigate the impact teacher support on academic its mechanism action, this study introduces two mediating variables—academic self-efficacy emotions—to construct chain mediation model, conducts survey among 800 university students in Nanjing. The findings reveal that directly impacts achievement; mediates effect emotions also...

The shot-noise unit (SNU) is a crucial factor for the practical security of continuous-variable quantum key distribution system. In most widely used experimental scheme, SNU should be calibrated first and acts as constant during distribution. However, system dependent on various parameters local oscillator (LO), which can controlled by eavesdropper in open channel. this paper, we report hacking method to control using limited compensation rate polarization compensation. Since only based...

Twin-field quantum key distribution (TF-QKD) and its variant protocols are highly attractive due to the advantage of overcoming rate-loss limit for secret rates point-to-point QKD protocols. For variations TF-QKD, point ensure security is switching randomly between a code mode test mode. Among all TF-QKD protocols, their modes very different, e.g. modulating continuous phases, only two opposite sending or not signal pulses. Here we show that, by discretizing number global phases in mode, can...

The value of residual phase noise, after compensation, is one the key limitations performance improvement for continuous-variable quantum distribution using a local oscillator (LLO CV-QKD) system, since it major excess noise. However, due to nonideality realistic devices implemented in practice, example, imperfect lasers, detectors, and unbalanced interferometers, noise current system still relatively large. Here, we develop model improve tolerance LLO CV-QKD schemes. In our model, part...

We present a photonic approach for fast quantum random number generation based on optically sampled amplified spontaneous emission (ASE). This utilizes terahertz optical asymmetric demultiplexer to sample the ASE and then digitize pulses into bits using multi-bit parallel comparator. A proof-of-concept experiment demonstrates that 40 Gb/s with verified randomness can be obtained our method. The current rate is mainly limited by bandwidth of available source.

Quantum Random Number Generators (QRNGs) have been theoretically proven to be able generate completely unpredictable random sequences, and important applications in many fields. However, the practical implementation of QRNG is always susceptible unwanted classical noise or device imperfections, which inevitably diminishes quality generated bits. It necessary perform post-processing extract true quantum randomness contained raw data by entropy source QRNG. In this work, a novel method for...

The Niemann-Pick C1-Like 1 (NPC1L1) protein, primarily expressed in the epithelial cells of small intestine, is essential for cholesterol absorption from both dietary intake and biliary secretion. Despite this conserved function across mammals, full-length coding sequence NPC1L1 remains uncharacterized key avian models including chicken (Gallus gallus), quail (Coturnix japonica), duck (Anas platyrhynchos). In study, we successfully cloned full mRNA chicken, quail, duck, entire 5' 3'...

We present a random number generation scheme based on measuring the phase fluctuations of laser with simple experimental setup. A model is established to analyze randomness and simulation result this fits well experiment data. After analog digital sampling suitable extraction integrated in field programmable gate array, final bits are delivered PC, realizing 5.4 Gbps real time quantum generation. The bit sequences have passed all NIST DIEHARD tests.