Beyond QAOA: A Review of AI and Quantum Computing for Adaptive Combinatorial Optimization
Organizations: School of Computing and Information Systems, Singapore Management University, Singapore
Abstract
Near-term quantum approaches to combinatorial optimization are limited by qubit counts, circuit fidelity, sampling cost, and the difficulty of encoding constraints, while machine learning is increasingly used to configure and control quantum optimization workflows. We call such workflows adaptive: decisions conventionally fixed in advance, from formulation and penalties to shot budgets, backends, and whether to invoke a quantum processor at all, are made by learned policies that respond to the instance, the progress of the solve, or the hardware. This review examines three paradigms, AI for quantum optimization, quantum for AI-driven optimization, and AI-quantum co-optimization, and organizes the literature by the decision being learned rather than by application. A structured review of 119 papers, 67 coded in detail, shows that the evidence is considerably stronger for AI-assisted quantum optimization than for the reverse direction: learning already reduces quantum evaluations, improves initialization, supports decomposition and penalty control, and mitigates noise, whereas evidence that quantum computation improves learned optimizers remains largely confined to small-scale simulation. Experimental controls are thin: 25 of 57 studies include no classical baseline, the quantum contribution is fully isolated in 10 of 24 studies where an ablation applies, and the median experiment uses 17 qubits. We introduce an M0-M5 evidence hierarchy, from simulation to matched-resource practical advantage, and find no broadly convincing result at the highest level. We argue that scaling is increasingly a systems problem: the question is not only whether a problem fits on a quantum processor, but how classical and quantum resources should be allocated across the optimization process. The review is aimed at researchers in quantum computing, machine learning, and operations research.
Figures & tables
| Term | Meaning in this review | Classical analogy |
|---|---|---|
| Qubit | Quantum bit; one per binary decision variable in a standard QUBO mapping | Binary variable |
| QUBO / Ising | Unconstrained quadratic objective over binary or variables ( Equations 1 and 2 ) | Quadratic 0–1 program |
| Hamiltonian | Operator whose energy encodes an objective; encodes the cost | Objective function |
| Shot | One preparation and measurement, returning one bitstring | One random sample |
| Circuit depth | Number of sequential gate layers | Sequential steps |
| Two-qubit gate | Interaction between two qubits; main error source | Costly, error-prone operation |
| Review | Primary scope | AI interventions | Q-for-AI | Workflow / evidence synthesis |
|---|---|---|---|---|
| Abbas et al. [ 7 ] | Quantum optimization broadly | Limited / distributed | No | Complexity, algorithms, benchmarking |
| Blekos et al. [ 8 ] | QAOA and variants | Parameter / variant coverage | No | Algorithm-centric |
| Gemeinhardt et al. [ 19 ] | NISQ combinatorial optimization | Incidental | No | Systematic mapping by problems and methods |
| Alexeev et al. [ 21 ] | AI across the quantum stack | Broad AI-for-quantum | Limited | Quantum-stack-centric |
| Martyniuk et al. [ 22 ] | Quantum architecture search | Circuit architecture | No | Search-space / strategy taxonomy |
| This review | AI Quantum for combinatorial optimization | Parameters through solver policies | Yes | Pipeline taxonomy + M0–M5 evidence hierarchy |
| Pipeline stage | Decision learned | Typical AI methods | Quantum component | Primary metric |
|---|---|---|---|---|
| Parameter initialization | QAOA/VQA angles | GNNs, meta-learning, clustering, diffusion | QAOA/VQA | calls, convergence, quality |
| Query control | next parameter point | Bayesian optimization, online surrogates | QAOA/VQA | evaluations, shots |
| Circuit / ansatz design | operators, gates, depth, topology | RL, differentiable NAS, transformers/LLMs | QAOA/VQA | depth, calls, quality |
| Formulation / penalties | QUBO coefficients, constraints | RL, learned surrogates, GNNs | QUBO for VQE, QAOA, annealing | feasibility, qubits, gap |
| Reduction / decomposition | subgraphs, variables, subproblems | GNNs, multilevel learning, RL | local quantum subproblems | scale, gap, width |
| Sampling / measurement | shots, CVaR level, recursion budget | RL, adaptive control | measurement loop | shots, confidence |
| Problem family | Why it matters | Dominant AI–quantum approaches | Main bottleneck | Research opportunity |
|---|---|---|---|---|
| MaxCut | clean benchmark; extensive QAOA literature | parameter transfer, BO, QAS, error mitigation | benchmark saturation; no hard constraints | cross-topology and hardware transfer |
| MIS / clique | constraint-sensitive graph structure | recursive policies, QAOA/QRAO, learned graph models | feasibility–compression trade-offs | adaptive encoding and resource allocation |
| TSP | canonical sequential CO | equivariant QRL, quantum attention | all-to-all interactions; shot sensitivity | hardware-aware learned routing policies |
| CVRP / VRP | realistic constrained routing | decomposition, RL control, quantum local repair | formulations; capacity and time windows | selective quantum subproblems and repair |
| Knapsack / MDKP | compact but constraint-rich | QRAO, slack-free penalties, Hamiltonian QRL | inequality encoding; feasible sampling | adaptive penalty and compression selection |
| QAP / assignment | bridge between QUBO and learned prediction | QNNs, end-to-end quantum learning | dense coupling; sparse feasible states | amortized prediction vs. per-instance solve |
| Level | Evidence requirement | Establishes | Does not establish |
|---|---|---|---|
| M0 | conceptual mechanism or architecture | plausibility | empirical effectiveness |
| M1 | ideal statevector or exact simulation | proof of concept | noise robustness or scaling |
| M2 | held-out, cross-size, cross-topology, or cross-problem tests | some generalization | hardware viability |
| M3 | realistic noise or physical-QPU validation of a material component | hardware relevance of that component | end-to-end system benefit |
| M4 | complete hybrid workflow with physical quantum execution | operational hardware integration | practical superiority |
| M5 | matched-resource comparison against strong classical and static-hybrid alternatives | practical system advantage in the tested regime | asymptotic quantum advantage, unless separately proven |
| Dimension | Minimum reporting expectation |
|---|---|
| Solution quality | gap or approximation ratio; best-case and distributional performance |
| Feasibility | feasible-sample rate; constraint violation; repair |
| Quantum resources | qubits; two-qubit gates; depth |
| Sampling | shots per call; total shots; allocation policy |
| Invocation cost | QPU calls or annealer submissions |
| Time | training; classical compute; QPU execution; queue time where material |