Research On Integrated Control System In Spaceborne Quantum Key Distribution And Superconducting Quantum Computing

As an interdiscipline of quantum mechanics and information science,quantum in-formation processing has enjoyed great development(at an increasingly speed).Quan-tum communication and quantum computing are two fastest developing directions in this field.With the use of quantum no cloning theorem,it guarantees the unconditional security of quantum cryptography,and make it possible that quantum information can transport through fiber media and free-space over 100 kilometers.For the application of quantum key distribution in Manned Space Flight,miniaturized terminal equipment as well as integrated quantum key distribution control system are required.The application of quantum superposition and entanglement principal enables quan-tum computing has incomparable advantage over classic computer.According to the theory,when there is 50 Qubits,the computing capacity of quantum computer will sur-pass the present classical super computer in specific aspects.It is estimated that Google will launch quantum computer with 50 Qubits,and achieves ’ quantum supremacy’.As the most possible method to fulfill quantum computing,superconducting quantum Qubit has good performance on fidelity,dephasing time and integrated level.Further-more,the semiconductor technique makes the massive expansion of Qubits possible.This raises many performance requirements for the measurement and control system from different aspects,including the preparation of microwave signal,the consistency of synchronization of multichannel signal,extensibility,feedback time,spatial constraints etc.Based on the need of miniaturized QKD control system in manned space engineer-ing,with the employment of SoC integrated control system,this thesis designs a such system,which consists of the preparation of random numbers,timing synchronization,quantum laser pulse modulation,receiving and dispatching of modulated laser,key dis-tillation algorithm etc..This system is implemented in a FPGA with PowerPC 405 hard-core processor.It improved the system integrated level and decreased the control interaction of each function module.System has passed rigorous environment ground tests,as well as function tests.In orbit operation,time synchronization precision,laser temperature control precision and other performance indexes are all meet the system de-sign requirement.It placed a good technical foundation for the following development of miniaturized satellite QKD control system.For superconducting quantum computing,the control over quantum qubits is im-plemented through microwave signal,and AWG is a commonly used method to produce modulated microwave signal.However commercial equipment with such function can-not custom control logic and has less flexibility.Besides,it takes too much room,as the Qubit number increased,the limited space will be a disadvantage to experiments.Meanwhile,a better Qubit fidelity and dephasing time also has higher requirement for the signal source’ s sampling speed,as well as vertical resolution.Therefore,tak-ing AWG as the prototype,this thesis designed a high-integrated AWG and applied in quantum computing experiment,with its sampling rate achieving 2GSPS and vertical resolution achieving 16.In scalable quantum computing system,when the number of Qubit increases,the controlled channel increase linearly along with it,as well as the inter-channel synchronous precision still within 100ps.With the employment of source synchronous clock technique,this thesis designed a scalable multichannel synchronous control system with synchronization jitter achieving 20ps,every channel has its own independent and adjustable delay.All these satisfy the requirement of Qubit control over a period of time.This thesis accomplished the research and development of multichannel data con-trol and receiving system,high speed and precision AWG,high precision synchroniza-tion control system.It also established a set of scalable superconductive quantum con-trol and measure system,and based on this we finished 10 Qubits sample control exper-iment.The innovations of this thesis are as follows:1.Take advantage of SoC integrated control and hardware-software co-design technique,we realized satellite based miniaturized QKD experimental terminal.The system has passed a series of environment tests as well as in-orbit tests,and has finished 400 to 700 kilometers Tiangong-2 space lab based quantum key distribution.2.It developed a scalable room temperature electronic control system for su-perconducting quantum Qubit control,the multichannel AWG,with its sampling rate achieving 2GHz and 16 bit vertical resolution.It has finished a 10 Qubits sample con-trol test.3.It developed a synchronous system whose synchronization precision reached 20ps,the number of synchronous channel is 40 and scalable.All these has meet the quantum computing’ s technical requirement for high-precision synchronization.