QAOAAnsatz¶

class QAOAAnsatz(local_field=<class 'qiskit.circuit.library.standard_gates.ry.RYGate'>)[source]¶

QAOA-style ansatz inspired by Killoran et al. (2020).

Each of the L layers consists of a Hadamard encoding layer followed by a weight Hamiltonian:

for n_qubits == 1 — a single local-field rotation;
for n_qubits == 2 — one RZZ on the pair, then one local field per qubit (no wrap-around);
for n_qubits >= 3 — RZZ gates on a closed ring (i ↔ (i+1) % n), then one local field per qubit.

A trailing Hadamard layer is applied after the L-th weight Hamiltonian. The default local field is RYGate.

Parameters:: local_field (type[Gate]) – Single-qubit rotation used as the local field. Must be one of RXGate, RYGate, RZGate. Defaults to RYGate.

Methods Summary

`build`(params, n_qubits, n_layers, **kwargs)	Build the QAOA ansatz circuit.
`n_params_per_layer`(n_qubits, **kwargs)	Per-layer parameter count.

Methods Documentation

build(params, n_qubits, n_layers, **kwargs)[source]¶

Build the QAOA ansatz circuit.

Parameters:

params – Flat parameter array of length n_layers * n_params_per_layer(n_qubits).
n_qubits (int) – Number of qubits.
n_layers (int) – Number of QAOA layers.
**kwargs – Additional unused arguments.

Returns:

Qiskit circuit implementing the QAOA ansatz.

Return type:

QuantumCircuit

static n_params_per_layer(n_qubits, **kwargs)[source]¶

Per-layer parameter count.