G. Zhang

FPGA-based electronic system for the control and readout of superconducting qubit systems

  1. Y. Yang,
  2. Z. Shen,
  3. X. Zhu,
  4. Z. Wang,
  5. G. Zhang,
  6. J. Zhou,
  7. C. Deng,
  8. S. Liu,
  9. and Q. An
This paper reports the development of an electronic system for the control and readout of superconducting qubits. The system includes a timing control module (TCM), four-channel arbitrary
waveform generators (AWGs), four-channel data acquisition modules (DAQs), six-channel bias voltage generators (BVGs), a controller card, and mixers. The AWGs have a 2-GSa/s sampling rate and a 14-bit amplitude resolution. The DAQs provide a 1-GSa/s sampling rate and 12-bit amplitude resolution. The BVGs provide an ultra-precise DC voltage with a noise level of ~6 {\mu}Vp-p. The TCM sends system clock and global triggers to each module through a high-speed backplane to achieve precise timing control. These modules are implemented in a field-programmable gate array (FPGA). While achieving highly customized functions, the physical interface and communication protocol are compatible with each other. The modular design is suitable for quantum computing experiments of different scales up to hundreds of qubits. We implement a real-time digital signal processing system in the FPGA, enabling precise timing control, arbitrary waveform generation, parallel IQ demodulation for qubit state discrimination, and the generation of real-time qubit-state-dependent trigger signals for active feedback control. We demonstrate the functionalities and performance of this system using a fluxonium quantum processor.
arxiv pdf

Direct digital synthesis of microwave waveforms for quantum computing

  1. J. Raftery,
  2. A. Vrajitoarea,
  3. G. Zhang,
  4. Z. Leng,
  5. S. J. Srinivasan,
  6. and A. A. Houck
Current state of the art quantum computing experiments in the microwave regime use control pulses generated by modulating microwave tones with baseband signals generated by an arbitrary
waveform generator (AWG). Recent advances in digital analog conversion technology have made it possible to directly synthesize arbitrary microwave pulses with sampling rates up to 92 gigasamples per second (GS/s). These new high bandwidth AWG’s could dramatically simplify the classical control chain for quantum computing experiments, enabling more advanced pulse shaping and reducing the number of components that need to be carefully calibrated. Here we use a high speed AWG to study the viability of such a simplified scheme. We characterize the AWG and perform randomized benchmarking of a superconducting qubit, achieving average single qubit gate error rates below 5×10−4.
arxiv pdf