qrunch.quantum.algorithms.second_quantization.orbital_optimizers.gradient_calculator

Module dedicated to general (full-domain) orbital optimization gradient and Hessian computations.

This interface is intended for scenarios where gradients and Hessians can be computed for any parameter set, not just around a single reference point.

Classes

FiniteDifferencesGradientCalculator

Class to construct the gradient and hessian for orbital optimization using finite differences.

class FiniteDifferencesGradientCalculator

Bases: GradientCalculator

Class to construct the gradient and hessian for orbital optimization using finite differences.

__init__(estimator: Estimator, mapper: Mapper | None = None, *, epsilon: float = 1e-05, restricted: bool = False) → None

Initialize the gradient calculator using finite differences.

Parameters:

estimator (Estimator) – Estimator to use for estimating.
mapper (Mapper | None) – Mapper to use when mapping RDM operators.
epsilon (float) – The finite difference. Defaults to 1e-5.
restricted (bool) – Whether the calculation should be performed restricted. Defaults to False.

Return type:

None

clear_cache() → None

Clear the cache of the estimator.

Return type:: None

compute_energy(operator: FermionHermitianSumProtocol | PairedHardcoreBosonHermitianSumProtocol, circuit: Circuit, shots: int | None = None) → float

Compute the energy.

Parameters:

operator (FermionHermitianSumProtocol | PairedHardcoreBosonHermitianSumProtocol) – Operator to estimate the energy of.
circuit (Circuit) – The circuit ansatz with minimized parameters set.
shots (int | None) – The number of shots to use in the estimator.

Return type:

float

compute_gradient(operator: FermionHermitianSumProtocol | PairedHardcoreBosonHermitianSumProtocol, circuit: Circuit, shots: int | None = None) → ndarray[Any, dtype[float64]]

Compute the gradient.

Parameters:

operator (FermionHermitianSumProtocol | PairedHardcoreBosonHermitianSumProtocol) – Operator to estimate the gradient from.
circuit (Circuit) – The circuit ansatz with minimized parameters set.
shots (int | None) – The number of shots to use in the estimator.

Return type:

ndarray[Any, dtype[float64]]

compute_hessian(operator: FermionHermitianSumProtocol | PairedHardcoreBosonHermitianSumProtocol, circuit: Circuit, shots: int | None = None) → ndarray[Any, dtype[float64]]

Compute the Hessian.

Parameters:

operator (FermionHermitianSumProtocol | PairedHardcoreBosonHermitianSumProtocol) – Operator to estimate the Hessian from.
circuit (Circuit) – The circuit ansatz with minimized parameters set.
shots (int | None) – The number of shots to use in the estimator.

Return type:

ndarray[Any, dtype[float64]]

get_estimator_shots() → int

Get the total amount of shots made by the estimator.

Return type:: int

is_restricted() → bool

Return True if the calculation is restricted.

Return type:: bool