QAOAAnsatz
class qiskit.circuit.library.QAOAAnsatz(cost_operator=None, reps=1, initial_state=None, mixer_operator=None, name='QAOA', flatten=None)
Bases: 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 (BaseOperator or 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 (BaseOperator or 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’
- flatten (bool | None) – Set this to
Trueto output a flat circuit instead of nesting it inside multiple layers of gate objects. By default currently the contents of the output circuit will be wrapped in nested objects for cleaner visualization. However, if you’re using this circuit for anything besides visualization its strongly recommended to set this flag toTrueto avoid a large performance overhead for parameter binding.
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
BaseOperator or OperatorBase
data
entanglement
Get the entanglement strategy.
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.
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";'
flatten
Returns whether the circuit is wrapped in nested gates/instructions or flattened.
global_phase
Return the global phase of the current circuit scope in radians.
header
Default value: 'OPENQASM 2.0;'
initial_state
Returns an optional initial state as a circuit
insert_barriers
If barriers are inserted in between the layers or not.
Returns
True, if barriers are inserted in between the layers, False if not.
instances
Default value: 328
layout
Return any associated layout information about the circuit
This attribute contains an optional TranspileLayout object. This is typically set on the output from transpile() or PassManager.run() to retain information about the permutations caused on the input circuit by transpilation.
There are two types of permutations caused by the transpile() function, an initial layout which permutes the qubits based on the selected physical qubits on the Target, and a final layout which is an output permutation caused by SwapGates inserted during routing.
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.
mixer_operator
Returns an optional mixer operator expressed as an operator or a quantum circuit.
Returns
mixer operator or circuit.
Return type
BaseOperator or OperatorBase or QuantumCircuit, optional
num_ancillas
Return the number of ancilla qubits.
num_clbits
Return number of classical bits.
num_layers
Return the number of layers in the n-local circuit.
Returns
The number of layers in the circuit.
num_parameters
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.
Returns
The number of parameters originally available in the circuit.
This quantity does not require the circuit to be built yet.
num_qubits
op_start_times
Return a list of operation start times.
This attribute is enabled once one of scheduling analysis passes runs on the quantum circuit.
Returns
List of integers representing instruction start times. The index corresponds to the index of instruction in QuantumCircuit.data.
Raises
AttributeError – When circuit is not scheduled.
operators
The operators that are evolved in this circuit.
Returns
The operators to be evolved
(and circuits) in this ansatz.
Return type
List[Union[BaseOperator, 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])]Returns
The parameters objects used in the circuit.
parameter_bounds
The parameter bounds for the unbound parameters in the circuit.
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
preferred_init_points
Getter of preferred initial points based on the given initial state.
prefix
Default value: 'circuit'
qregs
Type: list[QuantumRegister]
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.
rotation_blocks
The blocks in the rotation layers.
Returns
The blocks in the rotation layers.