Development Of Electronics System For CVQKD Experiment In Quantum Communication

More and more attention has been paid to information security due to the rapid development of communication engineering.In this era of big data and informationization,information leakage incidents occur from time to time.The existing cryptosystems relying on mathematical complexity are far from meeting the security needs of society.In the field of information,quantum characteristics have unique functions,which are expected to break the limits of existing classic information systems in terms of ensuring information security and increasing information capacity.In recent years,quantum information has made important breakthroughs in the fields of theory,experiment and application.Among them,quantum confidential communication is based on the laws of quantum physics as a security guarantee,and combines the disciplines of classical cryptography and classical communication theory.As a new research field and practical technology combining quantum mechanics,electronic information science,and computer science,quantum secure communication has realized commercial applications to a certain extent,and has broad market application prospects,especially in military,financial,Information security and other fields.In the field of quantum communication,quantum key distribution(QKD)enables two remote communication parties,Alice and Bob,to achieve theoretical and unconditional secure communication.QKD experimental system mainly includes optical system(laser,amplitude modulator,phase modulator,adjustable optical attenuator,electronically controlled polarization controller,etc.),detector system(synchronous photodetector,single photon detector,homodyne detector,etc.)and electronics systems.The main work of the author of this thesis during the doctoral period was focused on the development of the electronic system in the QKD experimental system,including the control of the amplitude modulator and phase modulator in the QKD(MDIQKD)experimental system independent of the measurement equipment,and the control and adjustment of the optical system in Gaussian modulated continuous variable QKD(CVQKD)experimental system control,as well as data acquisition and data post-processing of the detector system in the Gaussian modulated CVQKD,as well as the generation of random numbers.According to the design goal of the CVQKD experiment,the electronics system is divided into a light source control system and a main control system.The light source control system is mainly responsible for the direct control of the optical components.It supports the 100 kHz synchronous optical laser;the repetition frequency of the drive voltage pulse provided to the modulator is 20 MHz,the width of the flat area is 10 ns,and the pulse delay adjustment step value 10 ps,the delay range is 50 ns,and the rising and falling edges of the pulse signal are less than 2 ns;and can generate multiple stable voltages in the range of 0 V?5 V,which are different optical components(modulator,laser,Electric variable attenuator,electric polarization controller,discriminator,etc.)provide driving.The performance of the light source control system meets its design requirements.The main control system of the CVQKD experiment is mainly responsible for data acquisition,data post-processing,and random number generation.Realize the generation of 800 MHz and 400 MHz high-frequency clocks required by the system,and the quality is good.The duty ratio is basically 50%,with negligible shaking.The ADC used for high-speed data acquisition has good dynamic performance,the signal-to-noise ratio is better than 55.31 dB,the signal-to-noise distortion ratio is better than 52.71 dB,the effective number of bits is higher than 8.46 bit and can reach 9.07 bit(200 MHz).The verification of the Gaussian random number generated by the system conforms to the Gaussian distribution,the expected value ? is 32771,the standard deviation ? is 12383,and the data rate meets the system requirements.The two channel random number verification obtained through the ASIC chip conforms to a uniform distribution and is much greater than the data rate required by the system.And successfully implemented Gigabit Ethernet communication based on FPGA.For the CVQKD experiment,the performance indicators of the electronics system developed in this paper can meet the requirements of the Gaussian-modulated CVQKD experiment.According to the requirements of the MDIQKD experiment on the modulation signal,the developed voltage pulse generator has an output pulse frequency of 75 MHz and a load of 50?.The maximum output amplitude is up to 8 V,and the output pulse rise and fall times are as low as 500 ps.Moreover,the intensity modulator can achieve the best performance,and the extinction ratio can reach the order of 10000:1.The time error rate of the final system is about 0.034%and the phase error rate of the phase state is about 28%,which meets the design requirements of the experiment.This article first introduces the theoretical basis,related protocols and experimental progress of QKD,then introduced the CVQKD experimental system based on Gaussian modulation,focusing on the detailed design of each part of the entire electronic system(including the light source control system and the main control system).Then introduces the structure of the MDIQKD experimental system,and elaborate on the specific design details of the voltage pulse generator module in the electronics system.Finally,the test results of the important indicators of these electronic modules are given.This paper has the following innovations in the development of electronic systems in quantum communications:1.For the CVQKD experimental system of Gaussian modulation,research on key technologies such as high-speed data acquisition,Gigabit Ethernet communication,high-speed parallel Gaussian true random number generation,completed the design of the electronic control system,and developed a set of multi-function Light source control system to control and adjust optical modules such as lasers,modulators,electrically tunable optical attenuators,and electronically controlled polarization controllers.2.In the design of the Gaussian modulation CVQKD electronics system,the main control system and the light source control system of the sender Alice and the receiver Bob adopt a consistent design,saving the research and development costs of electronics,shortening the research and development cycle,and conducive to later maintenance.And in the random number generation part,the use of domestically produced small-volume,low-power random number generator ASIC chip reduces the system's space occupation and power consumption.3.In response to the modulator signal requirements of the MDIQKD experimental system,a multi-channel,high-speed,high-bandwidth,high-drive capability,real-time adjustable voltage pulse generator has been specially developed to improve system integration and ensure smooth experiment.Completed and achieved very good scientific research results.