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SparseVectorStateFn

SparseVectorStateFn(primitive, coeff=1.0, is_measurement=False)

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Bases: qiskit.opflow.state_fns.state_fn.StateFn

A class for sparse state functions and measurements in vector representation.

This class uses scipy.sparse.spmatrix for the internal representation.

Parameters

  • primitive (spmatrix) – The underlying sparse vector.
  • coeff (Union[complex, ParameterExpression]) – A coefficient multiplying the state function.
  • is_measurement (bool) – Whether the StateFn is a measurement operator

Raises

  • ValueError – If the primitive is not a column vector.
  • ValueError – If the number of elements in the primitive is not a power of 2.

Methods Defined Here

add

SparseVectorStateFn.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

OperatorBase

Returns

An OperatorBase equivalent to the sum of self and other.

adjoint

SparseVectorStateFn.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

SparseVectorStateFn

Returns

An OperatorBase equivalent to the adjoint of self.

equals

SparseVectorStateFn.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

SparseVectorStateFn.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.

primitive_strings

SparseVectorStateFn.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.

sample

SparseVectorStateFn.sample(shots=1024, massive=False, reverse_endianness=False)

Sample the state function as a normalized probability distribution. Returns dict of bitstrings in order of probability, with values being probability.

Parameters

  • shots (int) – The number of samples to take to approximate the State function.
  • massive (bool) – Whether to allow large conversions, e.g. creating a matrix representing over 16 qubits.
  • reverse_endianness (bool) – Whether to reverse the endianness of the bitstrings in the return dict to match Terra’s big-endianness.

Return type

dict

Returns

A dict containing pairs sampled strings from the State function and sampling frequency divided by shots.

to_circuit_op

SparseVectorStateFn.to_circuit_op()

Convert this state function to a CircuitStateFn.

Return type

OperatorBase

to_dict_fn

SparseVectorStateFn.to_dict_fn()

Convert this state function to a DictStateFn.

Return type

StateFn

Returns

A new DictStateFn equivalent to self.

to_matrix

SparseVectorStateFn.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

SparseVectorStateFn.to_matrix_op(massive=False)

Return a VectorStateFn for this StateFn.

Parameters

massive (bool) – Whether to allow large conversions, e.g. creating a matrix representing over 16 qubits.

Return type

OperatorBase

Returns

A VectorStateFn equivalent to self.

to_spmatrix

SparseVectorStateFn.to_spmatrix()

Return SciPy sparse matrix representation of the Operator. Represents the evaluation of the Operator’s underlying function on every combination of basis binary strings.

Return type

OperatorBase

Returns

The SciPy spmatrix equivalent to this Operator.


Attributes

INDENTATION

= '  '

coeff

A coefficient by which the state function is multiplied.

Return type

Union[complex, ParameterExpression]

instance_id

Return the unique instance id.

Return type

int

is_measurement

Whether the StateFn object is a measurement Operator.

Return type

bool

num_qubits

Return type

int

parameters

primitive

scipy.sparse._base.spmatrix

The primitive which defines the behavior of the underlying State function.

settings

Return settings.

Return type

Dict

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