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ComposedOp

class ComposedOp(oplist, coeff=1.0, abelian=False)[source]

Bases: ListOp

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

Deprecated since version 0.24.0: The class qiskit.opflow.list_ops.composed_op.ComposedOp 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 composed.

  • 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

adjoint

Return a new Operator equal to the Operator's adjoint (conjugate transpose), overloaded by ~.

compose

Return Operator Composition between self and other (linear algebra-style: A@B(x) = A(B(x))), overloaded by @.

eval

Evaluate the Operator's underlying function, either on a binary string or another Operator.

non_distributive_reduce

Reduce without attempting to expand all distributive compositions.

reduce

Try collapsing the Operator structure, usually after some type of conversion, e.g.

to_circuit

Returns the quantum circuit, representing the composed operator.

to_matrix

Return NumPy representation of the Operator.

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.