QuCtrl-BELL: A Compiler-Driven Sub-Microsecond Feedback Control Stack for Scalable Trapped-Ion Quantum Experiments

TL;DR

QuCtrl-BELL introduces a compiler-driven control stack for trapped-ion quantum computing, enabling sub-microsecond feedback with modular software and hardware decoupling, improving scalability and maintainability.

Contribution

It presents a novel compiler-based software stack that decouples control flow from hardware data, supporting deterministic, low-latency feedback for scalable trapped-ion quantum experiments.

Findings

Achieved feedback latency below 700 ns without host intervention.

Deployed on QuCtrl-BELL platform demonstrating programmability and modularity.

Compiler pipeline effectively manages control flow and hardware synchronization.

Abstract

As trapped-ion quantum computing scales to larger qubit registers and more complex control protocols, classical control systems face a fundamental tradeoff: sub-microsecond board-level feedback requires tight hardware coupling, whereas maintainability and extensibility require clean, modular software abstractions. This paper presents QuCtrl-BELL (Bell), a compiler-driven software stack for trapped-ion quantum control. The design resolves this tradeoff by decoupling control flow -- including loops, branches, and synchronization -- from hardware state data. A Python-embedded domain-specific language (DSL) is lowered through a six-stage transpilation pipeline covering control flow graph (CFG) construction, static single-assignment (SSA) conversion, liveness analysis, and graph-coloring register allocation. The compiler generates deterministic distributed board-level programs and compact step-table data. A cross-board synchronization protocol supports feedback loops with latency below 700~ns without host intervention. Bell is deployed and evaluated on the QuCtrl-BELL platform (RISC-V + PXIe), demonstrating that a compiler-based infrastructure can provide programmability, deterministic timing, and modularity for scalable trapped-ion quantum control.