Computing Library › Quantum Algorithms
Quantum Algorithms
QAOA (Quantum Approximate Optimization Algorithm)
QAOA is a hybrid algorithm for combinatorial optimization — it alternates problem and mixing layers to approximate good solutions to hard discrete problems.
- Type
- hybrid variational
- Targets
- MaxCut, scheduling, portfolio, routing
- Depth
- p layers trade quality for circuit depth
What it does
Encode the objective as a cost Hamiltonian. QAOA alternates a cost-phase unitary and a mixing unitary p times, with 2p classical parameters optimized to maximize the expected objective. Higher p approaches the optimum but costs depth.
Where it's used
Combinatorial optimization — a natural fit for logistics, scheduling, and design-space search problems.
In code (Qiskit)
python
from qiskit.circuit.library import QAOAAnsatz
# build cost Hamiltonian, then optimize gamma/beta angles