Interdisciplinary Instrumentation Colloquium

Gang Huang (LBNL) and Yilun Xu (LBNL) "QubiC: An Open Source FPGA-Based Control and Measurement System for Superconducting Quantum Information Processors"


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As quantum information processors grow in quantum bit (qubit) count and functionality, the control and measurement system becomes a limiting factor to large scale extensibility. To tackle this challenge and keep pace with rapidly evolving classical control requirements, full control stack access is essential to system level optimization. We design a modular FPGA (field-programmable gate array) based system called QubiC to control and measure a superconducting quantum processing unit. The system includes room temperature electronics hardware, FPGA gateware, and engineering software. A prototype hardware module is assembled from several commercial off-the-shelf evaluation boards and in-house developed circuit boards. Gateware and software are designed to implement basic qubit control and measurement protocols. System functionality and performance are demonstrated by performing qubit chip characterization, gate optimization, and randomized benchmarking sequences on a superconducting quantum processor operating at the Advanced Quantum Testbed at Lawrence Berkeley National Laboratory. The single-qubit and two-qubit Clifford gate infidelities are measured to be 4.9(1.1)×10^−4 and 1.4(3)×10^−2 by randomized benchmarking. With fast circuit sequence loading capability, the QubiC performs randomized compiling experiments efficiently and improves the feasibility of executing more complex algorithms.
Gang Huang is a staff scientist at Accelerator Technology and Applied Physics Division in LBNL. He received the B.S. degree in engineering physics and the Ph.D. degree in accelerator technology and application from Tsinghua University in 1997 and 2002. He led the QubiC development since 2018. His research interests include FPGA-based RF control for quantum computing, low level RF control system for particle accelerators, femto-second timing and synchronization, and ultrafast beam diagnostic.
Yilun Xu is a research scientist at Accelerator Technology and Applied Physics Division in LBNL. He received the B.S. degree and the Ph.D. degree in engineering physics from Tsinghua University, Beijing, China, in 2013 and 2018. He is one of the main developers of QubiC since 2018. His research interests include RF control systems for applied physics facilities (including quantum computing, laser, and particle accelerator), and FPGA-based digital signal processing and feedback control.