CircuitOp

class qiskit.opflow.primitive_ops.CircuitOp(*args, **kwargs)

Bases: PrimitiveOp

Deprecated: Class for Operators backed by Terra’s QuantumCircuit module.

Deprecated since version 0.24.0: The class qiskit.opflow.primitive_ops.circuit_op.CircuitOp is deprecated as of qiskit-terra 0.24.0. It will be removed no earlier than 3 months after the release date. For code migration guidelines, visit https://qisk.it/opflow_migration.

Parameters:

• primitive – The QuantumCircuit which defines the

• function. (behavior of the underlying) –

• coeff – A coefficient multiplying the primitive

Raises:

TypeError – Unsupported primitive, or primitive has ClassicalRegisters.

Attributes

INDENTATION = '  '

coeff

The scalar coefficient multiplying the Operator.

Returns:

The coefficient.

instance_id

Return the unique instance id.

num_qubits

parameters

primitive: QuantumCircuit

The primitive defining the underlying function of the Operator.

Returns:

The primitive object.

settings

Return operator settings.

Methods

add(other)

Return Operator addition of self and other, overloaded by +.

Parameters:

other (OperatorBase) – An OperatorBase with the same number of qubits as self, and in the same ‘Operator’, ‘State function’, or ‘Measurement’ category as self (i.e. the same type of underlying function).

Returns:

An OperatorBase equivalent to the sum of self and other.

Return type:

OperatorBase

adjoint()

Return a new Operator equal to the Operator’s adjoint (conjugate transpose), overloaded by ~. For StateFns, this also turns the StateFn into a measurement.

Returns:

An OperatorBase equivalent to the adjoint of self.

Return type:

CircuitOp

assign_parameters(param_dict)

Binds scalar values to any Terra Parameters in the coefficients or primitives of the Operator, or substitutes one Parameter for another. This method differs from Terra’s assign_parameters in that it also supports lists of values to assign for a give Parameter, in which case self will be copied for each parameterization in the binding list(s), and all the copies will be returned in an OpList. If lists of parameterizations are used, every Parameter in the param_dict must have the same length list of parameterizations.

Parameters:

param_dict (dict) – The dictionary of Parameters to replace, and values or lists of values by which to replace them.

Returns:

The OperatorBase with the Parameters in self replaced by the values or Parameters in param_dict. If param_dict contains parameterization lists, this OperatorBase is an OpList.

Return type:

OperatorBase

compose(other, permutation=None, front=False)

Return Operator Composition between self and other (linear algebra-style: A@B(x) = A(B(x))), overloaded by @.

Note: You must be conscious of Quantum Circuit vs. Linear Algebra ordering conventions. Meaning, X.compose(Y) produces an X∘Y on qubit 0, but would produce a QuantumCircuit which looks like

-[Y]-[X]-

Because Terra prints circuits with the initial state at the left side of the circuit.

Parameters:

• other (OperatorBase) – The OperatorBase with which to compose self.

• permutation (List[int] | None) – List[int] which defines permutation on other operator.

• front (bool) – If front==True, return other.compose(self).

Returns:

An OperatorBase equivalent to the function composition of self and other.

Return type:

OperatorBase

equals(other)

Evaluate Equality between Operators, overloaded by ==. Only returns True if self and other are of the same representation (e.g. a DictStateFn and CircuitStateFn will never be equal, even if their vector representations are equal), their underlying primitives are equal (this means for ListOps, OperatorStateFns, or EvolvedOps the equality is evaluated recursively downwards), and their coefficients are equal.

Parameters:

other (OperatorBase) – The OperatorBase to compare to self.

Returns:

A bool equal to the equality of self and other.

Return type:

bool

eval(front=None)

Evaluate the Operator’s underlying function, either on a binary string or another Operator. A square binary Operator can be defined as a function taking a binary function to another binary function. This method returns the value of that function for a given StateFn or binary string. For example, op.eval('0110').eval('1110') can be seen as querying the Operator’s matrix representation by row 6 and column 14, and will return the complex value at those “indices.” Similarly for a StateFn, op.eval('1011') will return the complex value at row 11 of the vector representation of the StateFn, as all StateFns are defined to be evaluated from Zero implicitly (i.e. it is as if .eval('0000') is already called implicitly to always “indexing” from column 0).

If front is None, the matrix-representation of the operator is returned.

Parameters:

front (str | Dict[str, complex] | ndarray | OperatorBase | Statevector | None) – The bitstring, dict of bitstrings (with values being coefficients), or StateFn to evaluated by the Operator’s underlying function, or None.

Returns:

The output of the Operator’s evaluation function. If self is a StateFn, the result is a float or complex. If self is an Operator (PrimitiveOp, ComposedOp, SummedOp, EvolvedOp, etc.), the result is a StateFn. If front is None, the matrix-representation of the operator is returned, which is a MatrixOp for the operators and a VectorStateFn for state-functions. If either self or front contain proper ListOps (not ListOp subclasses), the result is an n-dimensional list of complex or StateFn results, resulting from the recursive evaluation by each OperatorBase in the ListOps.

Return type:

OperatorBase | complex

permute(permutation)

Permute the qubits of the circuit.

Parameters:

permutation (List[int]) – A list defining where each qubit should be permuted. The qubit at index j of the circuit should be permuted to position permutation[j].

Returns:

A new CircuitOp containing the permuted circuit.

Return type:

CircuitOp

primitive_strings()

Return a set of strings describing the primitives contained in the Operator. For example, {'QuantumCircuit', 'Pauli'}. For hierarchical Operators, such as ListOps, this can help illuminate the primitives represented in the various recursive levels, and therefore which conversions can be applied.

Returns:

A set of strings describing the primitives contained within the Operator.

Return type:

Set[str]

reduce()

Try collapsing the Operator structure, usually after some type of conversion, e.g. trying to add Operators in a SummedOp or delete needless IGates in a CircuitOp. If no reduction is available, just returns self.

Returns:

The reduced OperatorBase.

Return type:

OperatorBase

tensor(other)

Return tensor product between self and other, overloaded by ^. Note: You must be conscious of Qiskit’s big-endian bit printing convention. Meaning, X.tensor(Y) produces an X on qubit 0 and an Y on qubit 1, or X⨂Y, but would produce a QuantumCircuit which looks like

-[Y]- -[X]-

Because Terra prints circuits and results with qubit 0 at the end of the string or circuit.

Parameters:

other (OperatorBase) – The OperatorBase to tensor product with self.

Returns:

An OperatorBase equivalent to the tensor product of self and other.

Return type:

CircuitOp | TensoredOp

to_circuit()

Returns a QuantumCircuit equivalent to this Operator.

Return type:

QuantumCircuit

to_circuit_op()

Returns a CircuitOp equivalent to this Operator.

Return type:

CircuitOp

to_instruction()

Returns an Instruction equivalent to this Operator.

Return type:

Instruction

to_matrix(massive=False)

Return NumPy representation of the Operator. Represents the evaluation of the Operator’s underlying function on every combination of basis binary strings. Warn if more than 16 qubits to force having to set massive=True if such a large vector is desired.

Returns:

The NumPy ndarray equivalent to this Operator.

Return type:

ndarray