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MatrixOp

MatrixOp(primitive, coeff=1.0)

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Bases: qiskit.opflow.primitive_ops.primitive_op.PrimitiveOp

Class for Operators represented by matrices, backed by Terra’s Operator module.

Parameters

  • primitive (Union[list, ndarray, spmatrix, Operator]) – The matrix-like object which defines the behavior of the underlying function.
  • coeff (Union[complex, ParameterExpression]) – A coefficient multiplying the primitive

Raises

  • TypeError – invalid parameters.
  • ValueError – invalid parameters.

Methods Defined Here

add

MatrixOp.add(other)

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

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

Union[MatrixOp, SummedOp]

Returns

An OperatorBase equivalent to the sum of self and other.

adjoint

MatrixOp.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.

Return type

MatrixOp

Returns

An OperatorBase equivalent to the adjoint of self.

compose

MatrixOp.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.

Parameters

  • other (OperatorBase) – The OperatorBase with which to compose self.
  • permutation (Optional[List[int]]) – List[int] which defines permutation on other operator.
  • front (bool) – If front==True, return other.compose(self).

Return type

OperatorBase

Returns

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

equals

MatrixOp.equals(other)

Evaluate Equality between Operators, overloaded by ==. Only returns True if self and other are of the same representation (e.g. a DictStateFn and CircuitStateFn will never be equal, even if their vector representations are equal), their underlying primitives are equal (this means for ListOps, OperatorStateFns, or EvolvedOps the equality is evaluated recursively downwards), and their coefficients are equal.

Parameters

other (OperatorBase) – The OperatorBase to compare to self.

Return type

bool

Returns

A bool equal to the equality of self and other.

eval

MatrixOp.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).

If front is None, the matrix-representation of the operator is returned.

Parameters

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

Return type

Union[OperatorBase, complex]

Returns

The output of the Operator’s evaluation function. If self is a StateFn, the result is a float or complex. If self is an Operator (PrimitiveOp, ComposedOp, SummedOp, EvolvedOp, etc.), the result is a StateFn. If front is None, the matrix-representation of the operator is returned, which is a MatrixOp for the operators and a VectorStateFn for state-functions. 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.

exp_i

MatrixOp.exp_i()

Return a CircuitOp equivalent to e^-iH for this operator H

Return type

OperatorBase

permute

MatrixOp.permute(permutation=None)

Creates a new MatrixOp that acts on the permuted qubits.

Parameters

permutation (Optional[List[int]]) – A list defining where each qubit should be permuted. The qubit at index j should be permuted to position permutation[j].

Return type

OperatorBase

Returns

A new MatrixOp representing the permuted operator.

Raises

OpflowError – if indices do not define a new index for each qubit.

primitive_strings

MatrixOp.primitive_strings()

Return a set of strings describing the primitives contained in the Operator. For example, {'QuantumCircuit', 'Pauli'}. For hierarchical Operators, such as ListOps, this can help illuminate the primitives represented in the various recursive levels, and therefore which conversions can be applied.

Return type

Set[str]

Returns

A set of strings describing the primitives contained within the Operator.

tensor

MatrixOp.tensor(other)

Return tensor product between self and other, overloaded by ^. Note: You must be conscious of Qiskit’s big-endian bit printing convention. Meaning, X.tensor(Y) produces an X on qubit 0 and an Y on qubit 1, or X⨂Y, but would produce a QuantumCircuit which looks like

-[Y]- -[X]-

Because Terra prints circuits and results with qubit 0 at the end of the string or circuit.

Parameters

other (OperatorBase) – The OperatorBase to tensor product with self.

Return type

Union[MatrixOp, TensoredOp]

Returns

An OperatorBase equivalent to the tensor product of self and other.

to_instruction

MatrixOp.to_instruction()

Returns an Instruction equivalent to this Operator.

Return type

Instruction

to_matrix

MatrixOp.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.

Return type

ndarray

Returns

The NumPy ndarray equivalent to this Operator.

to_matrix_op

MatrixOp.to_matrix_op(massive=False)

Returns a MatrixOp equivalent to this Operator.

Return type

MatrixOp


Attributes

INDENTATION

= '  '

coeff

The scalar coefficient multiplying the Operator.

Return type

Union[complex, ParameterExpression]

Returns

The coefficient.

instance_id

Return the unique instance id.

Return type

int

num_qubits

Return type

int

parameters

primitive

qiskit.quantum_info.operators.operator.Operator

The primitive defining the underlying function of the Operator.

Return type

Union[QuantumCircuit, Operator, Pauli, SparsePauliOp, OperatorBase]

Returns

The primitive object.

settings

Return operator settings.

Return type

Dict

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