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CircuitOp

CircuitOp(primitive, coeff=1.0)

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Bases: qiskit.opflow.primitive_ops.primitive_op.PrimitiveOp

Class for Operators backed by Terra’s QuantumCircuit module.

Parameters

  • primitive (Union[Instruction, QuantumCircuit]) – The QuantumCircuit which defines the
  • function. (behavior of the underlying) –
  • coeff (Union[complex, ParameterExpression]) – A coefficient multiplying the primitive

Raises

TypeError – Unsupported primitive, or primitive has ClassicalRegisters.


Methods Defined Here

add

CircuitOp.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).

Return type

OperatorBase

Returns

An OperatorBase equivalent to the sum of self and other.

adjoint

CircuitOp.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.

Return type

CircuitOp

Returns

An OperatorBase equivalent to the adjoint of self.

assign_parameters

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.

Return type

OperatorBase

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.

compose

CircuitOp.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 (Optional[List[int]]) – List[int] which defines permutation on other operator.
  • front (bool) – If front==True, return other.compose(self).

Return type

OperatorBase

Returns

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

equals

CircuitOp.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.

Return type

bool

Returns

A bool equal to the equality of self and other.

eval

CircuitOp.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 (Union[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.

Return type

Union[OperatorBase, complex]

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.

permute

CircuitOp.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].

Return type

CircuitOp

Returns

A new CircuitOp containing the permuted circuit.

primitive_strings

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.

Return type

Set[str]

Returns

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

reduce

CircuitOp.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.

Return type

OperatorBase

Returns

The reduced OperatorBase.

tensor

CircuitOp.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.

Return type

Union[CircuitOp, TensoredOp]

Returns

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

to_circuit

CircuitOp.to_circuit()

Returns a QuantumCircuit equivalent to this Operator.

Return type

QuantumCircuit

to_circuit_op

CircuitOp.to_circuit_op()

Returns a CircuitOp equivalent to this Operator.

Return type

CircuitOp

to_instruction

CircuitOp.to_instruction()

Returns an Instruction equivalent to this Operator.

Return type

Instruction

to_matrix

CircuitOp.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.

Return type

ndarray

Returns

The NumPy ndarray equivalent to this Operator.


Attributes

INDENTATION

= '  '

coeff

The scalar coefficient multiplying the Operator.

Return type

Union[complex, ParameterExpression]

Returns

The coefficient.

instance_id

Return the unique instance id.

Return type

int

num_qubits

Return type

int

parameters

primitive

qiskit.circuit.quantumcircuit.QuantumCircuit

The primitive defining the underlying function of the Operator.

Return type

Union[QuantumCircuit, Operator, Pauli, SparsePauliOp, OperatorBase]

Returns

The primitive object.

settings

Return operator settings.

Return type

Dict

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