Skip to main contentIBM Quantum Documentation
You are viewing the API reference for an old version of Qiskit. Switch to latest version

SummedOp

SummedOp(oplist, coeff=1.0, abelian=False)GitHub(opens in a new tab)

Bases: qiskit.opflow.list_ops.list_op.ListOp

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.

Parameters

  • oplist (List[OperatorBase]) – The Operators being summed.
  • coeff (Union[complex, ParameterExpression]) – A coefficient multiplying the operator
  • abelian (bool) – Indicates whether the Operators in oplist are known to mutually commute.

Methods Defined Here

add

SummedOp.add(other)GitHub(opens in a new tab)

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).

Return type

SummedOp

Returns

A SummedOp equivalent to the sum of self and other.

collapse_summands

SummedOp.collapse_summands()GitHub(opens in a new tab)

Return Operator by simplifying duplicate operators.

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

Return type

SummedOp

Returns

A simplified SummedOp equivalent to self.

equals

SummedOp.equals(other)GitHub(opens in a new tab)

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.

Return type

bool

Returns

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

Examples

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

reduce

SummedOp.reduce()GitHub(opens in a new tab)

Try collapsing list or trees of sums.

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

Return type

OperatorBase

Returns

A collapsed version of self, if possible.

to_circuit

SummedOp.to_circuit()GitHub(opens in a new tab)

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.

Return type

QuantumCircuit

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**)****.** –

to_matrix_op

SummedOp.to_matrix_op(massive=False)GitHub(opens in a new tab)

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

Return type

SummedOp

to_pauli_op

SummedOp.to_pauli_op(massive=False)GitHub(opens in a new tab)

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

Return type

SummedOp


Attributes

INDENTATION

= '  '

abelian

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

Return type

bool

Returns

A bool indicating whether the oplist is Abelian.

coeff

The scalar coefficient multiplying the Operator.

Return type

Union[complex, ParameterExpression]

Returns

The coefficient.

coeffs

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

Return type

List[Union[complex, ParameterExpression]]

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.

Return type

Callable

Returns

The combination function.

distributive

Return type

bool

grad_combo_fn

The gradient of combo_fn.

Return type

Optional[Callable]

instance_id

Return the unique instance id.

Return type

int

num_qubits

Return type

int

oplist

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

Return type

List[OperatorBase]

Returns

The Operators defining the ListOp

parameters

settings

Return settings.

Return type

Dict

Was this page helpful?