qrunch.quantum.algorithms.second_quantization.orbital_optimizers.simple_orbital_optimizer

Module containing the simple orbital optimizer.

Classes

SimpleOrbitalOptimizer

An orbital optimizer using a simple cost function and any Minimizer to perform the optimization.
class SimpleOrbitalOptimizer

Bases: OrbitalOptimizerAlgorithm

An orbital optimizer using a simple cost function and any Minimizer to perform the optimization.

__init__(estimator: Estimator, minimizer: Minimizer, mapper: Mapper | None = None, shots: int | ShotsPerGroup | None = None) → None

Initialize orbital optimizer.

Parameters:

  • estimator (Estimator) – The estimator to use in the cost function.

  • minimizer (Minimizer) – The minimizer to use in the orbital optimization algorithm.

  • mapper (Mapper | None) – Mapper to use for creating qubit operators.

  • shots (int | ShotsPerGroup | None) – Number of shots to use for the estimator.

Return type:

None

clear_cache() → None

Clear the cache of the underlying estimator.

Return type:

None

gradient_norm(operator: FermionHermitianSum | PairedHardcoreBosonHermitianSum, circuit: Circuit) → float | None

Compute the norm of the orbital-optimization gradient at zero rotation.

The method return None, as the SimpleOrbitalOptimizer does not have an analytical gradient.

Parameters:
Return type:

float | None

property mapper: Mapper

Mapper.

run(operator: T, circuit: Circuit) → OrbitalOptimizerResult[T]

Run the orbital optimization and find the eigenvalue.

The orbital optimizer rotates the observable so that the expectation value is minimized.

Parameters:

  • operator (T) – The operator whose expectation value should be minimized.

  • circuit (Circuit) – The parametrized circuit to find optimal parameters for. Should contain unspecified parameters.

  • callback – An optional callback function that is called at each minimizer iteration.

Return type:

OrbitalOptimizerResult[T]

run_single_step(operator: T, circuit: Circuit) → OrbitalOptimizerResult[T]

Perform a single, cheap orbital-optimization step.

Parameters:

  • operator (T) – The operator whose expectation value should be minimized.

  • circuit (Circuit) – The circuit ansatz with optimized parameters set.

Return type:

OrbitalOptimizerResult[T]