qiskit.opflow.list_ops.ComposedOp(oplist, coeff=1.0, abelian=False)
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.
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 (opens in a new tab).
- oplist (List (opens in a new tab)[OperatorBase]) – The Operators being composed.
- coeff (complex (opens in a new tab) |ParameterExpression) – A coefficient multiplying the operator
- abelian (bool (opens in a new tab)) – Indicates whether the Operators in
oplistare known to mutually commute.
= ' '
Whether the Operators in
oplist are known to commute with one another.
A bool indicating whether the
oplist is Abelian.
The scalar coefficient multiplying the Operator.
Return a list of the coefficients of the operators listed. Raises exception for nested Listops.
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
The combination function.
The gradient of
Return the unique instance id.
The list of
OperatorBases defining the underlying function of this Operator.
The Operators defining the ListOp
Return a new Operator equal to the Operator’s adjoint (conjugate transpose), overloaded by
~. For StateFns, this also turns the StateFn into a measurement.
OperatorBase equivalent to the adjoint of self.
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
Because Terra prints circuits with the initial state at the left side of the circuit.
- other (OperatorBase) – The
OperatorBasewith which to compose self.
- permutation (List (opens in a new tab)[int (opens in a new tab)] | None) –
List[int]which defines permutation on other operator.
- front (bool (opens in a new tab)) – If front==True, return
OperatorBase equivalent to the function composition of self and other.
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
front (str (opens in a new tab) |dict (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.
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.
- NotImplementedError (opens in a new tab) – Raised if called for a subclass which is not distributive.
- TypeError (opens in a new tab) – Operators with mixed hierarchies, such as a ListOp containing both PrimitiveOps and ListOps, are not supported.
- NotImplementedError (opens in a new tab) – Attempting to call ListOp’s eval from a non-distributive subclass.
Reduce without attempting to expand all distributive compositions.
The reduced Operator.
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.
Returns the quantum circuit, representing the composed operator.
The circuit representation of the composed operator.
OpflowError – for operators where a single underlying circuit can not be obtained.
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.
ndarray equivalent to this Operator.