PauliOp
class PauliOp(primitive, coeff=1.0)
Bases: qiskit.opflow.primitive_ops.primitive_op.PrimitiveOp
Class for Operators backed by Terra’s Pauli module.
Parameters
- primitive (
Pauli) – The Pauli which defines the behavior of the underlying function. - coeff (
Union[complex,ParameterExpression]) – A coefficient multiplying the primitive.
Raises
TypeError – invalid parameters.
Methods Defined Here
add
PauliOp.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
PauliOp.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.
compose
PauliOp.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
PauliOp.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
PauliOp.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
permute
PauliOp.permute(permutation)
Permutes the sequence of Pauli matrices.
Parameters
permutation (List[int]) – A list defining where each Pauli should be permuted. The Pauli at index j of the primitive should be permuted to position permutation[j].
Return type
Returns
A new PauliOp representing the permuted operator. For operator (X ^ Y ^ Z) and indices=[1,2,4], it returns (X ^ I ^ Y ^ Z ^ I).
Raises
OpflowError – if indices do not define a new index for each qubit.
primitive_strings
PauliOp.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.
tensor
PauliOp.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.
to_circuit
to_instruction
to_matrix
PauliOp.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_pauli_op
PauliOp.to_pauli_op(massive=False)
Returns a sum of PauliOp s equivalent to this Operator.
Return type
to_spmatrix
PauliOp.to_spmatrix()
Returns SciPy sparse matrix representation of the Operator.
Return type
spmatrix
Returns
CSR sparse matrix representation of the Operator.
Raises
ValueError – invalid parameters.
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
Type: qiskit.quantum_info.operators.symplectic.pauli.Pauli
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