QAOAAnsatz
class QAOAAnsatz(cost_operator=None, reps=1, initial_state=None, mixer_operator=None, name='QAOA')
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.
Parameters
- cost_operator (OperatorBase, optional) – The operator representing the cost of the optimization problem, denoted as 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 orQuantumCircuit, optional) – An optional custom mixer to use instead of the global X-rotations, denoted as 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.
Return type
List[AncillaQubit]
calibrations
Return calibration dictionary.
The custom pulse definition of a given gate is of the form
{‘gate_name’: {(qubits, params): schedule}}
Return type
dict
clbits
Returns a list of classical bits in the order that the registers were added.
Return type
List[Clbit]
cost_operator
Returns an operator representing the cost of the optimization problem.
Returns
cost operator.
Return type
data
entanglement
Get the entanglement strategy.
Return type
Union[str, List[str], List[List[str]], List[int], List[List[int]], List[List[List[int]]], List[List[List[List[int]]]], Callable[[int], str], Callable[[int], List[List[int]]]]
Returns
The entanglement strategy, see get_entangler_map() for more detail on how the format is interpreted.
entanglement_blocks
The blocks in the entanglement layers.
Return type
List[Instruction]
Returns
The blocks in the entanglement layers.
evolution
The evolution converter used to compute the evolution.
Returns
The evolution converter used to compute the evolution.
Return type
extension_lib
Default value: 'include "qelib1.inc";'
global_phase
Return the global phase of the circuit in radians.
Return type
Union[ParameterExpression, float]
header
Default value: 'OPENQASM 2.0;'
initial_state
Returns an optional initial state as a circuit
Return type
Optional[QuantumCircuit]
insert_barriers
If barriers are inserted in between the layers or not.
Return type
bool
Returns
True, if barriers are inserted in between the layers, False if not.
instances
Default value: 9
metadata
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.
Return type
dict
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.
Return type
int
num_clbits
Return number of classical bits.
Return type
int
num_layers
Return the number of layers in the n-local circuit.
Return type
int
Returns
The number of layers in the circuit.
num_parameters
Return type
int
num_parameters_settable
The number of total parameters that can be set to distinct values.
This does not change when the parameters are bound or exchanged for same parameters, and therefore is different from num_parameters which counts the number of unique Parameter objects currently in the circuit.
Return type
int
Returns
The number of parameters originally available in the circuit.
This quantity does not require the circuit to be built yet.
num_qubits
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]]
ordered_parameters
The parameters used in the underlying circuit.
This includes float values and duplicates.
Examples
>>> # prepare circuit ...
>>> print(nlocal)
┌───────┐┌──────────┐┌──────────┐┌──────────┐
q_0: ┤ Ry(1) ├┤ Ry(θ[1]) ├┤ Ry(θ[1]) ├┤ Ry(θ[3]) ├
└───────┘└──────────┘└──────────┘└──────────┘
>>> nlocal.parameters
{Parameter(θ[1]), Parameter(θ[3])}
>>> nlocal.ordered_parameters
[1, Parameter(θ[1]), Parameter(θ[1]), Parameter(θ[3])]Return type
List[Parameter]
Returns
The parameters objects used in the circuit.
parameter_bounds
The parameter bounds for the unbound parameters in the circuit.
Return type
Optional[List[Tuple[Optional[float], Optional[float]]]]
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.
parameters
Return type
ParameterView
preferred_init_points
Getter of preferred initial points based on the given initial state.
prefix
Default value: '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.
Return type
List[Qubit]
reps
Returns the reps parameter, which determines the depth of the circuit.
Return type
int
rotation_blocks
The blocks in the rotation layers.
Return type
List[Instruction]
Returns
The blocks in the rotation layers.