Quantum circuits utilizing real time feedback techniques (such as active reset and mid-circuit measurement) are a powerful tool for NISQ-era quantum computing. Such techniques are crucial for implementing error correction protocols, and can reduce the resource requirements of certain quantum algorithms. Realizing these capabilities requires flexible, low-latency classical control. We have developed a custom FPGA-based processor architecture for QubiC, an open source platform for superconducting qubit control. Our architecture is distributed in nature, and consists of a bank of lightweight cores, each configured to control a small (1-3) number of signal generator channels. Each core is capable of executing parameterized control and readout pulses, as well as performing arbitrary control flow based on mid-circuit measurement results. We have also developed a modular compiler stack and domain-specific intermediate representation for programming the processor. Our representation allows users to specify circuits using both gate and pulse-level abstractions, and includes high-level control flow constructs (e.g. if-else blocks and loops). The compiler stack is designed to integrate with quantum software tools and programming languages, such as TrueQ, pyGSTi, and OpenQASM3. In this work, we will detail the design of both the processor and compiler stack, and demonstrate its capabilities with a quantum state teleportation experiment using transmon qubits at the LBNL Advanced Quantum Testbed.

翻译：利用实时反馈技术（如主动复位和中路测量）的量子电路是NISQ时代量子计算的强大工具。此类技术对于实现纠错协议至关重要，并能降低某些量子算法的资源需求。实现这些能力需要灵活且低延迟的经典控制。我们为QubiC（一个开源超导量子比特控制平台）开发了定制FPGA处理器架构。该架构具有分布式特性，由一组轻量级核心组成，每个核心被配置为控制少量（1-3个）信号发生器通道。每个核心能够执行参数化控制和读出脉冲，并基于中路测量结果执行任意控制流。我们还开发了模块化编译器栈和领域特定中间表示来对处理器进行编程。该表示允许用户通过门级和脉冲级抽象指定电路，并包含高级控制流结构（例如if-else块和循环）。编译器栈设计为与量子软件工具和编程语言（如TrueQ、pyGSTi和OpenQASM3）集成。本文将详细阐述处理器和编译器栈的设计，并通过使用LBNL高级量子测试平台上的transmon量子比特进行的量子态隐形传态实验演示其能力。