QMon: Monitoring the Execution of Quantum Circuits with Mid-Circuit Measurement and Reset

2025-12-15

AI Summary

Quantum circuits are inherently difficult to debug and monitor at runtime due to the no-cloning theorem and wavefunction collapse upon measurement. This paper introduces the first runtime monitoring framework that jointly ensures high fidelity and observability: it enables localized error localization by inserting lightweight monitoring operators, performing mid-circuit measurements, and resetting qubits—without perturbing the original circuit behavior, including entanglement and other essential quantum properties. The framework continuously compares the expected quantum state with the empirically measured probability distribution, introducing negligible disturbance. Evaluated on 154 benchmark circuits, the approach achieves zero functional degradation, high error detection rates, and practical levels of coverage and robustness.

Technology Category

• Machine Learning: Quantum Machine Learning
• Planning, Routing, and Scheduling: Plan Execution and Monitoring
• Computer Vision: Adversarial Attacks & Robustness

Application Category

• Security and Privacy: Large-scale security measurements
• Economics, Online Markets and Human Computation: LLM based quality controls for crowd work
• Responsible Web: Human-perceived consequences of algorithmic deployment on the web

Abstract

Unlike classical software, where logging and runtime tracing can effectively reveal internal execution status, quantum circuits possess unique properties, such as the no-cloning theorem and measurement-induced collapse, that prevent direct observation or duplication of their states. These characteristics make it especially challenging to monitor the execution of quantum circuits, complicating essential tasks such as debugging and runtime monitoring. This paper presents QMON, a practical methodology that leverages mid-circuit measurements and reset operations to monitor the internal states of quantum circuits while preserving their original runtime behavior. QMON enables the instrumentation of monitoring operators at developer-specified locations within the circuit, allowing comparisons between expected and observed quantum-state probabilities at those locations. We evaluated QMON by analyzing its impact on circuit behavior, monitoring coverage, and effectiveness in bug localization. Experimental results involving 154 quantum circuits show that all circuits preserve their intended functionality after instrumentation and that QMON successfully detects and localizes various programming errors. Although monitoring coverage is limited by the need to preserve delicate quantum properties, such as entanglement, QMON effectively detects errors while introducing no or negligible disturbance to the original quantum states. QMON facilitates the development of more robust and reliable quantum software as the field continues to mature.

Problem

• Monitoring quantum circuit execution without altering behavior
• Enabling debugging and runtime monitoring via mid-circuit measurements
• Detecting and localizing programming errors while preserving entanglement

Innovation

• Leverages mid-circuit measurement and reset operations
• Enables instrumentation of monitoring operators at specified locations
• Preserves original circuit functionality while detecting errors