International Conference on AI-ML Systems (AIMLSystems)
A Transformer-GNN Framework for Learning Full Output Distributions of Quantum Circuits
Tourad Baba, Tianxiang Lu
Abstract
Comprehensive knowledge of a quantum circuit's full output distribution-beyond mere summary statistics-is crucial for benchmarking and hybrid algorithm development in the noisy intermediate-scale quantum (NISQ) computing era. However, existing prediction methods typically focus on scalar observables. We introduce an attention-enhanced Graph Neural Network (GNN) that learns entire output distributions directly from directed acyclic graph (DAG) representations of parameterized quantum circuits, incorporating structural, parametric, and noise-aware features. Formulated as supervised multi-output regression over the exponentially large$(2^{n})$probability space, our model consistently outperforms a capacity-matched convolutional neural network (CNN) baseline on 2 to 5 qubit circuits, achieving near-perfect fidelity (0.993) and reducing KL divergence by an order of magnitude. Evaluations on unseen 6-qubit circuits under zero-shot and few-shot conditions reveal expected performance degradation due to the exponential scaling, highlighting the importance of size-specific training. These findings demonstrate the inductive advantages of attention-based GNNs as a structureaware approach for distribution-level prediction in NISQ computing.