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StateFn

class StateFn(primitive=None, coeff=1.0, is_measurement=False)[código fonte]

Bases: OperatorBase

A class for representing state functions and measurements.

State functions are defined to be complex functions over a single binary string (as compared to an operator, which is defined as a function over two binary strings, or a function taking a binary function to another binary function). This function may be called by the eval() method.

Measurements are defined to be functionals over StateFns, taking them to real values. Generally, this real value is interpreted to represent the probability of some classical state (binary string) being observed from a probabilistic or quantum system represented by a StateFn. This leads to the equivalent definition, which is that a measurement m is a function over binary strings producing StateFns, such that the probability of measuring a given binary string b from a system with StateFn f is equal to the inner product between f and m(b).

NOTE: State functions here are not restricted to wave functions, as there is no requirement of normalization.

Parâmetros
  • primitive (Union[str, dict, Result, list, ndarray, Statevector, QuantumCircuit, Instruction, OperatorBase, None]) – The primitive which defines the behavior of the underlying State function.

  • coeff (Union[complex, ParameterExpression]) – A coefficient by which the state function is multiplied.

  • is_measurement (bool) – Whether the StateFn is a measurement operator

Methods Defined Here

add

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

adjoint

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

assign_parameters

Binds scalar values to any Terra Parameters in the coefficients or primitives of the Operator, or substitutes one Parameter for another.

compose

Composition (Linear algebra-style: A@B(x) = A(B(x))) is not well defined for states in the binary function model, but is well defined for measurements.

equals

Evaluate Equality between Operators, overloaded by ==.

eval

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

mul

Returns the scalar multiplication of the Operator, overloaded by *, including support for Terra's Parameters, which can be bound to values later (via bind_parameters).

permute

Permute the qubits of the state function.

power

Compose with Self Multiple Times, undefined for StateFns.

primitive_strings

Return a set of strings describing the primitives contained in the Operator.

reduce

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

sample

Sample the state function as a normalized probability distribution.

tensor

Return tensor product between self and other, overloaded by ^.

tensorpower

Return tensor product with self multiple times, overloaded by ^.

to_circuit_op

Returns a CircuitOp equivalent to this Operator.

to_density_matrix

Return matrix representing product of StateFn evaluated on pairs of basis states.

to_matrix

Return NumPy representation of the Operator.

to_matrix_op

Return a VectorStateFn for this StateFn.

traverse

Apply the convert_fn to the internal primitive if the primitive is an Operator (as in the case of OperatorStateFn).

Attributes

INDENTATION = '  '
coeff

A coefficient by which the state function is multiplied.

Tipo de retorno

Union[complex, ParameterExpression]

instance_id

Return the unique instance id.

Tipo de retorno

int

is_measurement

Whether the StateFn object is a measurement Operator.

Tipo de retorno

bool

num_qubits
Tipo de retorno

int

parameters
primitive

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

settings

Return settings.

Tipo de retorno

Dict