QAOAAnsatz¶

class QAOAAnsatz(cost_operator=None, reps=1, initial_state=None, mixer_operator=None, name='QAOA')[source]

Bases: qiskit.circuit.library.evolved_operator_ansatz.EvolvedOperatorAnsatz

A generalized QAOA quantum circuit with a support of custom initial states and mixers.

References

[1]: Farhi et al., A Quantum Approximate Optimization Algorithm.

arXiv:1411.4028

Parameters
• cost_operator (OperatorBase, optional) – The operator representing the cost of the optimization problem, denoted as $$U(C, \gamma)$$ in the original paper. Must be set either in the constructor or via property setter.

• reps (int) – The integer parameter p, which determines the depth of the circuit, as specified in the original paper, default is 1.

• initial_state (QuantumCircuit, optional) – An optional initial state to use. If None is passed then a set of Hadamard gates is applied as an initial state to all qubits.

• mixer_operator (OperatorBase or QuantumCircuit, optional) – An optional custom mixer to use instead of the global X-rotations, denoted as $$U(B, \beta)$$ in the original paper. Can be an operator or an optionally parameterized quantum circuit.

• name (str) – A name of the circuit, default ‘qaoa’

Attributes

ancillas

Returns a list of ancilla bits in the order that the registers were added.

calibrations

Return calibration dictionary.

The custom pulse definition of a given gate is of the form

{‘gate_name’: {(qubits, params): schedule}}

clbits

Returns a list of classical bits in the order that the registers were added.

cost_operator

Returns an operator representing the cost of the optimization problem.

Returns

cost operator.

Return type

OperatorBase

data
evolution

The evolution converter used to compute the evolution.

Returns

The evolution converter used to compute the evolution.

Return type

EvolutionBase

extension_lib = 'include "qelib1.inc";'
global_phase

Return the global phase of the circuit in radians.

initial_state

Returns an optional initial state as a circuit

Return type

Optional[QuantumCircuit]

instances = 16

The user provided metadata associated with the circuit

The metadata for the circuit is a user provided dict of metadata for the circuit. It will not be used to influence the execution or operation of the circuit, but it is expected to be passed between all transforms of the circuit (ie transpilation) and that providers will associate any circuit metadata with the results it returns from execution of that circuit.

mixer_operator

Returns an optional mixer operator expressed as an operator or a quantum circuit.

Returns

mixer operator or circuit.

Return type

OperatorBase or QuantumCircuit, optional

num_ancillas

Return the number of ancilla qubits.

num_clbits

Return number of classical bits.

num_parameters
Return type

int

num_qubits

Return the number of qubits, specified by the size of the cost operator.

Return type

int

operators

The operators that are evolved in this circuit.

Returns

The operators to be evolved (and circuits)

in this ansatz.

Return type

List[Union[OperatorBase, QuantumCircuit]]

parameter_bounds

Parameter bounds.

Returns: A list of pairs indicating the bounds, as (lower, upper). None indicates

an unbounded parameter in the corresponding direction. If None is returned, problem is fully unbounded or is not built yet.

Return type

List[Tuple[float, float]]

parameters

Get the Parameter objects in the circuit.

Return type

Set[Parameter]

Returns

A set containing the unbound circuit parameters.

preferred_init_points

Getter of preferred initial points based on the given initial state.

prefix = 'circuit'
qregs

A list of the quantum registers associated with the circuit.

qubits

Returns a list of quantum bits in the order that the registers were added.

reps

Returns the reps parameter, which determines the depth of the circuit.

Return type

int