PauliOp
class PauliOp(primitive=None, coeff=1.0)
Class for Operators backed by Terra’s Pauli
module.
Parameters
- primitive (
Optional
[Pauli
]) – The Pauli which defines the behavior of the underlying function. - coeff (
Union
[int
,float
,complex
,ParameterExpression
,None
]) – A coefficient multiplying the primitive.
Raises
TypeError – invalid parameters.
Attributes
coeff
Type: Union[int, float, complex, qiskit.circuit.parameterexpression.ParameterExpression]
The scalar coefficient multiplying the Operator.
Return type
Union
[int
, float
, complex
, ParameterExpression
]
Returns
The coefficient.
num_qubits
Type: int
The number of qubits over which the Operator is defined. If op.num_qubits == 5
, then op.eval('1' * 5)
will be valid, but op.eval('11')
will not.
Return type
int
Returns
The number of qubits accepted by the Operator’s underlying function.
primitive
Type: Union[qiskit.circuit.instruction.Instruction, qiskit.circuit.quantumcircuit.QuantumCircuit, list, numpy.ndarray, scipy.sparse.base.spmatrix, qiskit.quantum_info.operators.operator.Operator, qiskit.quantum_info.operators.pauli.Pauli]
The primitive defining the underlying function of the Operator.
Return type
Union
[Instruction
, QuantumCircuit
, list
, ndarray
, spmatrix
, Operator
, Pauli
]
Returns
The primitive object.
Methods
__mul__
PauliOp.__mul__(other)
Overload *
for Operator scalar multiplication.
Parameters
other (Number
) – 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.
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.
assign_parameters
PauliOp.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
.
bind_parameters
PauliOp.bind_parameters(param_dict)
Same as assign_parameters, but maintained for consistency with QuantumCircuit in Terra (which has both assign_parameters and bind_parameters).
Return type
commutes
PauliOp.commutes(other_op)
Returns whether self commutes with other_op.
Parameters
other_op (OperatorBase
) – An OperatorBase
with which to evaluate whether self commutes.
Return type
bool
Returns
A bool equaling whether self commutes with other_op
compose
PauliOp.compose(other)
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.
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).
Parameters
front (Union
[str
, dict
, ndarray
, OperatorBase
, None
]) – The bitstring, dict of bitstrings (with values being coefficients), or StateFn to evaluated by the Operator’s underlying function.
Return type
Union
[OperatorBase
, float
, 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 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
PauliOp.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
PauliOp.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
[int
, float
, 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.
neg
PauliOp.neg()
Return the Operator’s negation, effectively just multiplying by -1.0, overloaded by -
.
Return type
Returns
An OperatorBase
equivalent to the negation of self.
power
PauliOp.power(exponent)
Return Operator composed with self multiple times, overloaded by **
.
Parameters
exponent (int
) – The int number of times to compose self with itself.
Return type
Returns
An OperatorBase
equivalent to self composed with itself exponent times.
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.
reduce
PauliOp.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
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.
tensorpower
PauliOp.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
to_circuit_op
to_instruction
to_legacy_op
PauliOp.to_legacy_op(massive=False)
Attempt to return the Legacy Operator representation of the Operator. If self is a SummedOp
of PauliOps
, will attempt to convert to WeightedPauliOperator
, and otherwise will simply convert to MatrixOp
and then to MatrixOperator
. The Legacy Operators cannot represent StateFns
or proper ListOps
(meaning not one of the ListOp
subclasses), so an error will be thrown if this method is called on such an Operator. Also, Legacy Operators cannot represent unbound Parameter coeffs, so an error will be thrown if any are present in self.
Warn if more than 16 qubits to force having to set massive=True
if such a large vector is desired.
Return type
Returns
The LegacyBaseOperator
representing this Operator.
Raises
TypeError – self is an Operator which cannot be represented by a LegacyBaseOperator
, such as StateFn
, proper (non-subclass) ListOp
, or an Operator with an unbound coeff Parameter.
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_matrix_op
PauliOp.to_matrix_op(massive=False)
Returns a MatrixOp
equivalent to this Operator.
Return type
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.