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PauliOp

qiskit.opflow.primitive_ops.PauliOp(*args, **kwargs)

GitHub(opens in a new tab)

Bases: PrimitiveOp

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

Deprecated since version 0.24.0

The class qiskit.opflow.primitive_ops.pauli_op.PauliOp is deprecated as of qiskit-terra 0.24.0. It will be removed in the Qiskit 1.0 release. For code migration guidelines, visit https://qisk.it/opflow_migration(opens in a new tab).

Parameters

  • primitive – The Pauli which defines the behavior of the underlying function.
  • coeff – A coefficient multiplying the primitive.

Raises

TypeError(opens in a new tab) – invalid parameters.


Attributes

INDENTATION

= '  '

coeff

The scalar coefficient multiplying the Operator.

Returns

The coefficient.

instance_id

Return the unique instance id.

num_qubits

parameters

primitive

Pauli

The primitive defining the underlying function of the Operator.

Returns

The primitive object.

settings

Return operator settings.


Methods

add

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

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

PauliOp

compose

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

Returns

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

Return type

OperatorBase

equals

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(opens in a new tab)

eval

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(opens in a new tab) |Dict(opens in a new tab)[str(opens in a new tab), complex(opens in a new tab)] | ndarray(opens in a new tab) |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(opens in a new tab)

exp_i

exp_i()

Return a CircuitOp equivalent to e^-iH for this operator H.

Return type

OperatorBase

permute

permute(permutation)

Permutes the sequence of Pauli matrices.

Parameters

permutation (List(opens in a new tab)[int(opens in a new tab)]) – A list defining where each Pauli should be permuted. The Pauli at index j of the primitive should be permuted to position permutation[j].

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.

Return type

PauliOp

primitive_strings

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(opens in a new tab)[str(opens in a new tab)]

tensor

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

OperatorBase

to_circuit

to_circuit()

Returns a QuantumCircuit equivalent to this Operator.

Return type

QuantumCircuit

to_instruction

to_instruction()

Returns an Instruction equivalent to this Operator.

Return type

Instruction

to_matrix

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(opens in a new tab)

to_pauli_op

to_pauli_op(massive=False)

Returns a sum of PauliOp s equivalent to this Operator.

Return type

PauliOp

to_spmatrix

to_spmatrix()

Returns SciPy sparse matrix representation of the Operator.

Returns

CSR sparse matrix representation of the Operator.

Raises

ValueError(opens in a new tab) – invalid parameters.

Return type

spmatrix

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