PrimitiveOp
class PrimitiveOp(primitive, coeff=1.0)
Bases: qiskit.opflow.operator_base.OperatorBase
A class for representing basic Operators, backed by Operator primitives from Terra. This class (and inheritors) primarily serves to allow the underlying primitives to “flow” - i.e. interoperability and adherence to the Operator formalism - while the core computational logic mostly remains in the underlying primitives. For example, we would not produce an interface in Terra in which QuantumCircuit1 + QuantumCircuit2 equaled the Operator sum of the circuit unitaries, rather than simply appending the circuits. However, within the Operator flow summing the unitaries is the expected behavior.
Note that all mathematical methods are not in-place, meaning that they return a new object, but the underlying primitives are not copied.
Parameters
- primitive (
Union[QuantumCircuit,Operator,Pauli,SparsePauliOp,OperatorBase]) – The operator primitive being wrapped. - coeff (
Union[complex,ParameterExpression]) – A coefficient multiplying the primitive.
Methods Defined Here
add
PrimitiveOp.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
Returns
An OperatorBase equivalent to the sum of self and other.
adjoint
PrimitiveOp.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
Returns
An OperatorBase equivalent to the adjoint of self.
assign_parameters
PrimitiveOp.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
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
PrimitiveOp.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) – TheOperatorBasewith which to compose self. - permutation (
Optional[List[int]]) –List[int]which defines permutation on other operator. - front (
bool) – If front==True, returnother.compose(self).
Return type
Returns
An OperatorBase equivalent to the function composition of self and other.
equals
PrimitiveOp.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
PrimitiveOp.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.
exp_i
log_i
PrimitiveOp.log_i(massive=False)
Return a MatrixOp equivalent to log(H)/-i for this operator H. This function is the effective inverse of exp_i, equivalent to finding the Hermitian Operator which produces self when exponentiated.
Return type
mul
PrimitiveOp.mul(scalar)
Returns the scalar multiplication of the Operator, overloaded by *, including support for Terra’s Parameters, which can be bound to values later (via bind_parameters).
Parameters
scalar (Union[complex, ParameterExpression]) – The real or complex scalar by which to multiply the Operator, or the ParameterExpression to serve as a placeholder for a scalar factor.
Return type
Returns
An OperatorBase equivalent to product of self and scalar.
permute
PrimitiveOp.permute(permutation)
Permutes the qubits of the operator.
Parameters
permutation (List[int]) – A list defining where each qubit should be permuted. The qubit at index j should be permuted to position permutation[j].
Return type
Returns
A new OperatorBase containing the permuted operator.
Raises
OpflowError – if indices do not define a new index for each qubit.
primitive_strings
PrimitiveOp.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
PrimitiveOp.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
Returns
The reduced OperatorBase.
tensor
PrimitiveOp.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
Returns
An OperatorBase equivalent to the tensor product of self and other.
tensorpower
PrimitiveOp.tensorpower(other)
Return tensor product with self multiple times, overloaded by ^.
Parameters
other (int) – The int number of times to tensor product self with itself via tensorpower.
Return type
Union[OperatorBase, int]
Returns
An OperatorBase equivalent to the tensorpower of self by other.
to_circuit
PrimitiveOp.to_circuit()
Returns a QuantumCircuit equivalent to this Operator.
Return type
to_circuit_op
to_instruction
PrimitiveOp.to_instruction()
Returns an Instruction equivalent to this Operator.
Return type
to_matrix
PrimitiveOp.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.
to_matrix_op
PrimitiveOp.to_matrix_op(massive=False)
Returns a MatrixOp equivalent to this Operator.
Return type
to_pauli_op
PrimitiveOp.to_pauli_op(massive=False)
Returns a sum of PauliOp s equivalent to this Operator.
Return type
Attributes
INDENTATION
Default value: ' '
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
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