Design And Implementation Of Microwave Radiation Structure In Quantum Control Experiment

On the quantum control experiments based on solid-state spin,microwave and radio frequency signals are very important means of quantum state manipulation,and quantum states are very sensitive to the change of its frequency,amplitude,and phase.We realized the control of quantum states by generating microwave and radio frequency signals with a certain frequency,amplitude and phase,which coverts microwave and radio frequency energy into an alternating magnetic field efficiently with a special microwave and radiation structure after being amplified and then acts on the spin of the diamond NV color center.On the quantum control experimental platform based on solid-state spin,the transmission line for directional transmission of microwave information can be designed as the radiation structure of the microwave control module which can generate a strong alternating magnetic field in the specified area and then act on the diamond NV color center.The radiation area of this structure needs to have the characteristics of small thickness,good light transmittance,and strong alternating magnetic field.At present,the manufacturing technology of radiation structure is realized mostly by traditional micronano processing methods.The traditional process technology is relatively mature,but also has some shortcomings,such as the limited thickness of the magnetron sputtering metal layer,the weak bonding force between the metal layers,the high manufacturing cost,and the complicated procedures.This paper focuses on describing the new process method of coplanar waveguide radiation structure process.During the design,the magnetic field conversion rate is enhanced by reducing the line width and groove width of the signal in the central radiation area of the structure.However,this will also make the impedance change of the structure discontinuous,causing signal reflection.Therefore,the radiation area and the port area of the structure need design a transition zone to gradually change the impedance value of the structure to minimize energy loss.In this experiment,we used the electromagnetic simulation software CST MWS to conduct model analysis,simulation and parameter optimization of three-section region of the coplanar waveguide.This new process method is characterized by the use of conductive film materials combined with electrochemical copper plating to achieve the selective growth of metallic copper layers on high borosilicate glass.In the process of electrochemical copper plating,the width of the signal band and the ground band of the radiation structure metal layer increases due to the lateral growth of the copper layer.In this paper,through reckoning,we calculated the parameters of the laser-etched conductive film,carried out acidic electrochemical copper plating on the basis of it,and initially achieved the manufacturing of microwave radiation structure.Subsequently,we conducted the copper layer surface measurement and electrical test of the coplanar waveguide radiation structure realized by the process in this paper.Then,we applied it to the platform of solid-state spin quantum control experiment to verify the radiation performance.Finally,on the condition that the input power of the microwave source is about 1W,the coplanar waveguide radiation structure generates an effective alternating magnetic field with an intensity of about 6.58 Gauss at the frequency of 2.8 GHz.This method of replacing the traditional magnetron sputtering technology with a conductive film material to deposit a metal layer can greatly reduce the process flow,save time costs and material costs,and the implementation method has certain versatility.It is not only suitable for the production of coplanar waveguide radiation structure,but also can be applied to the realization of slot line and microstrip line radiation structure.