应用于 NV 系综量子实验调控的数字锁相放大器设计与实现

文章设计一种应用于金刚石氮空位(nitrogen-vacancy, NV)系综量子实验的数字锁相放大器。为实现高速模拟与数字信号的采样、输出以及软硬件协同与同步处理能力, 设计采用 ZYNQ-7010 芯片作为核心器件, 基于现场可编程门阵列(field programmable gate array, FPGA)与精简指令集计算机(reduced instruction set computer, RISC)微处理器(advanced RISC machines, ARM)内核的基本架构, 同时搭载双路高采样率的模数转换器(analog to digital converter, ADC)和数模转换器(digital to analog converter, DAC)。整套系统可以同时进行多路锁相放大处理, 输入模拟噪声低至 $ 1 \, nV/Hz^{1/2} $, 采样率高达 $ 125 \, MS/s $, 数据传输带宽可达 $ 800 \, Mib/s $, 具有集成化程度高、易操控、锁相准确性较高等特点。该设计成功应用在 NV 系综实验平台上, 光探测磁共振(optically detected magnetic resonance, ODMR)实验及后续计算结果表明, 使用文中锁相放大器的磁强计灵敏度可以达到 $ 1.23 \, nT/Hz^{1/2} $。

A digital lock-in amplifier for quantum experiments of nitrogen-vacancy(NV) ensemble in diamond is designed in this paper. In order to realize the sampling and output of high-speed analog and digital signals as well as the capability of hardware and software cooperation and synchronization processing, the design uses ZYNQ-7010 chip as the core device, with a basic architecture based on field programmable gate array(FPGA) and advanced RISC machines(ARM) core equipped with dual-channel high sampling rate analog to digital converter(ADC) and digital to analog converter(DAC). The whole system can perform multi-channel lock-in amplification simultaneously, the input analog noise is as low as 1 nV/Hz $ ^{1/2} $, sampling rate up to 125 MS/s, and data transmission bandwidth up to 800 Mib/s. It has the characteristics of high degree of integration, easy control and high accuracy of phase locking. The design in this paper has been successfully applied to the experimental platform of NV ensemble. The optically detected magnetic resonance(ODMR) experiment and subsequent calculation show that the sensitivity of the magnetometer using the lock-in amplifier in this paper can reach $ 1.23 \, nT/Hz^{1/2} $.