Gradient

class qiskit.opflow.gradients.Gradient(grad_method='param_shift', **kwargs)

Bases: GradientBase

Deprecated: Convert an operator expression to the first-order gradient.

Deprecated since version 0.24.0: The class qiskit.opflow.gradients.gradient.Gradient 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.

Attributes

grad_method

Returns CircuitGradient.

Returns:

CircuitGradient.

Methods

convert(operator, params=None)

Parameters:

• operator (OperatorBase) – The operator we are taking the gradient of.

• params (ParameterVector | ParameterExpression | List[ParameterExpression] | None) – The parameters we are taking the gradient with respect to. If not explicitly passed, they are inferred from the operator and sorted by name.

Returns:

An operator whose evaluation yields the Gradient.

Raises:

• ValueError – If params contains a parameter not present in operator.

• ValueError – If operator is not parameterized.

Return type:

OperatorBase

get_gradient(operator, params)

Get the gradient for the given operator w.r.t. the given parameters

Parameters:

• operator (OperatorBase) – Operator w.r.t. which we take the gradient.

• params (ParameterExpression | ParameterVector | List[ParameterExpression]) – Parameters w.r.t. which we compute the gradient.

Returns:

Operator which represents the gradient w.r.t. the given params.

Raises:

• ValueError – If params contains a parameter not present in operator.

• OpflowError – If the coefficient of the operator could not be reduced to 1.

• OpflowError – If the differentiation of a combo_fn requires JAX but the package is not installed.

• TypeError – If the operator does not include a StateFn given by a quantum circuit

• Exception – Unintended code is reached

• MissingOptionalLibraryError – jax not installed

Return type:

OperatorBase