ComposedOp

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

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.

Obsolète depuis la 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.

Paramètres:

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

• 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.

Renvoie:

A bool indicating whether the oplist is Abelian.

coeff

The scalar coefficient multiplying the Operator.

Renvoie:

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.

Renvoie:

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.

Renvoie:

The Operators defining the ListOp

parameters

settings

Return settings.

Methods

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.

Renvoie:

An OperatorBase equivalent to the adjoint of self.

Type renvoyé:

ComposedOp

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.

Paramètres:

• other (OperatorBase) – The OperatorBase with which to compose self.

• permutation (List[int] | None) – List[int] which defines permutation on other operator.

• front (bool) – If front==True, return other.compose(self).

Renvoie:

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

Type renvoyé:

OperatorBase

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).

ListOp’s eval recursively evaluates each Operator in oplist, and combines the results using the recombination function combo_fn.

Paramètres:

front (str | dict | ndarray | OperatorBase | Statevector | None) – The bitstring, dict of bitstrings (with values being coefficients), or StateFn to evaluated by the Operator’s underlying function.

Renvoie:

The output of the oplist Operators” evaluation function, combined with the combo_fn. 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.

Lève:

• NotImplementedError – Raised if called for a subclass which is not distributive.

• TypeError – Operators with mixed hierarchies, such as a ListOp containing both PrimitiveOps and ListOps, are not supported.

• NotImplementedError – Attempting to call ListOp’s eval from a non-distributive subclass.

Type renvoyé:

OperatorBase | complex

non_distributive_reduce()

Reduce without attempting to expand all distributive compositions.

Renvoie:

The reduced Operator.

Type renvoyé:

OperatorBase

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.

Renvoie:

The reduced OperatorBase.

Type renvoyé:

OperatorBase

to_circuit()

Returns the quantum circuit, representing the composed operator.

Renvoie:

The circuit representation of the composed operator.

Lève:

OpflowError – for operators where a single underlying circuit can not be obtained.

Type renvoyé:

QuantumCircuit

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.

Renvoie:

The NumPy ndarray equivalent to this Operator.

Type renvoyé:

ndarray