CircuitStateFn

class CircuitStateFn(primitive=None, coeff=1.0, is_measurement=False, from_operator=False)

Bases: qiskit.opflow.state_fns.state_fn.StateFn

A class for state functions and measurements which are defined by the action of a QuantumCircuit starting from |0⟩, and stored using Terra’s QuantumCircuit class.

Parameters

• primitive (Union[QuantumCircuit, Instruction, None]) – The QuantumCircuit (or Instruction, which will be converted) which defines the behavior of the underlying function.

• coeff (Union[complex, ParameterExpression]) – A coefficient multiplying the state function.

• is_measurement (bool) – Whether the StateFn is a measurement operator.

• from_operator (bool) – if True the StateFn is derived from OperatorStateFn. (Default: False)

Raises

TypeError – Unsupported primitive, or primitive has ClassicalRegisters.

Methods Defined Here

add	Return Operator addition of self and other, overloaded by +.
adjoint	Return a new Operator equal to the Operator’s adjoint (conjugate transpose), overloaded by ~.
assign_parameters	Binds scalar values to any Terra Parameters in the coefficients or primitives of the Operator, or substitutes one Parameter for another.
compose	Composition (Linear algebra-style: A@B(x) = A(B(x))) is not well defined for states in the binary function model, but is well defined for measurements.
eval	Evaluate the Operator’s underlying function, either on a binary string or another Operator.
from_dict	Construct the CircuitStateFn from a dict mapping strings to probability densities.
from_vector	Construct the CircuitStateFn from a vector representing the statevector.
permute	Permute the qubits of the circuit.
primitive_strings	Return a set of strings describing the primitives contained in the Operator.
reduce	Try collapsing the Operator structure, usually after some type of conversion, e.g.
sample	Sample the state function as a normalized probability distribution.
tensor	Return tensor product between self and other, overloaded by ^.
to_circuit	Return QuantumCircuit representing StateFn
to_circuit_op	Return StateFnCircuit corresponding to this StateFn.
to_density_matrix	Return numpy matrix of density operator, warn if more than 16 qubits to force the user to set massive=True if they want such a large matrix.
to_instruction	Return Instruction corresponding to primitive.
to_matrix	Return NumPy representation of the Operator.

Attributes

INDENTATION = ' '

coeff

A coefficient by which the state function is multiplied.

Return type

Union[complex, ParameterExpression]

instance_id

Return the unique instance id.

Return type

int

is_measurement

Whether the StateFn object is a measurement Operator.

Return type

bool

num_qubits

Return type

int

parameters

primitive: qiskit.circuit.quantumcircuit.QuantumCircuit

The primitive which defines the behavior of the underlying State function.

settings

Return settings.

Return type

Dict