FiniteDiffEstimatorGradient

class FiniteDiffEstimatorGradient(estimator, epsilon, options=None, *, method='central')

Bases: BaseEstimatorGradient

Compute the gradients of the expectation values by finite difference method [1].

Reference: [1] Finite difference method

Parâmetros

• estimator (BaseEstimator) – The estimator used to compute the gradients.

• epsilon (float) – The offset size for the finite difference gradients.

• options (Options | None) – Primitive backend runtime options used for circuit execution. The order of priority is: options in run method > gradient’s default options > primitive’s default setting. Higher priority setting overrides lower priority setting

• method (Literal[('central', 'forward', 'backward')]) –

  The computation method of the gradients.

  • central computes \(\frac{f(x+e)-f(x-e)}{2e}\),

  • forward computes \(\frac{f(x+e) - f(x)}{e}\),

  • backward computes \(\frac{f(x)-f(x-e)}{e}\)

  where \(e\) is epsilon.

Levanta

• ValueError – If epsilon is not positive.

• TypeError – If method is invalid.

Methods

run	Run the job of the estimator gradient on the given circuits.
update_default_options	Update the gradient's default options setting.

Attributes

derivative_type

Return the derivative type (real, imaginary or complex).

Retorno

The derivative type.

options

Return the union of estimator options setting and gradient default options, where, if the same field is set in both, the gradient’s default options override the primitive’s default setting.

Retorno

The gradient default + estimator options.