SummedOp

class qiskit.opflow.list_ops.SummedOp(oplist, coeff=1.0, abelian=False)

Bases: ListOp

Deprecated: A class for lazily representing sums of Operators. Often Operators cannot be efficiently added to one another, but may be manipulated further so that they can be later. This class holds logic to indicate that the Operators in oplist are meant to be added together, and therefore if they reach a point in which they can be, such as after evaluation or conversion to matrices, they can be reduced by addition.

Deprecated since version 0.24.0: The class qiskit.opflow.list_ops.summed_op.SummedOp is deprecated as of qiskit-terra 0.24.0. It will be removed no earlier than 3 months after the release date. For code migration guidelines, visit https://qisk.it/opflow_migration.

Parameters:

• oplist (List[OperatorBase]) – The Operators being summed.

• coeff (complex | ParameterExpression) – A coefficient multiplying the operator

• abelian (bool) – Indicates whether the Operators in oplist are known to mutually commute.

Attributes

INDENTATION = '  '

abelian

Whether the Operators in oplist are known to commute with one another.

Returns:

A bool indicating whether the oplist is Abelian.

coeff

The scalar coefficient multiplying the Operator.

Returns:

The coefficient.

coeffs

Return a list of the coefficients of the operators listed. Raises exception for nested Listops.

combo_fn

The function defining how to combine oplist (or Numbers, or NumPy arrays) to produce the Operator’s underlying function. For example, SummedOp’s combination function is to add all of the Operators in oplist.

Returns:

The combination function.

distributive

grad_combo_fn

The gradient of combo_fn.

instance_id

Return the unique instance id.

num_qubits

oplist

The list of OperatorBases defining the underlying function of this Operator.

Returns:

The Operators defining the ListOp

parameters

settings

Return settings.

Methods

add(other)

Return Operator addition of self and other, overloaded by +.

Note

This appends other to self.oplist without checking other is already included or not. If you want to simplify them, please use simplify().

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:

A SummedOp equivalent to the sum of self and other.

Return type:

SummedOp

collapse_summands()

Return Operator by simplifying duplicate operators.

E.g., SummedOp([2 * X ^ Y, X ^ Y]).collapse_summands() -> SummedOp([3 * X ^ Y]).

Returns:

A simplified SummedOp equivalent to self.

Return type:

SummedOp

equals(other)

Check if other is equal to self.

Note

This is not a mathematical check for equality. If self and other implement the same operation but differ in the representation (e.g. different type of summands) equals will evaluate to False.

Parameters:

other (OperatorBase) – The other operator to check for equality.

Returns:

True, if other and self are equal, otherwise False.

Return type:

bool

Examples

>>> from qiskit.opflow import X, Z
>>> 2 * X == X + X
True
>>> X + Z == Z + X
True

reduce()

Try collapsing list or trees of sums.

Tries to sum up duplicate operators and reduces the operators in the sum.

Returns:

A collapsed version of self, if possible.

Return type:

OperatorBase

to_circuit()

Returns the quantum circuit, representing the SummedOp. In the first step, the SummedOp is converted to MatrixOp. This is straightforward for most operators, but it is not supported for operators containing parameterized PrimitiveOps (in that case, OpflowError is raised). In the next step, the MatrixOp representation of SummedOp is converted to circuit. In most cases, if the summands themselves are unitary operators, the SummedOp itself is non-unitary and can not be converted to circuit. In that case, ExtensionError is raised in the underlying modules.

Returns:

The circuit representation of the summed operator.

Raises:

• OpflowError – if SummedOp can not be converted to MatrixOp (e.g. SummedOp is composed of

• parameterized PrimitiveOps). –

Return type:

QuantumCircuit

to_matrix_op(massive=False)

Returns an equivalent Operator composed of only NumPy-based primitives, such as MatrixOp and VectorStateFn.

Return type:

SummedOp

to_pauli_op(massive=False)

Returns an equivalent Operator composed of only Pauli-based primitives, such as PauliOp.

Return type:

SummedOp