qrunch.chemistry.calculators.quantum_phase_estimation_calculator

Module containing a QPE-based ground state energy calculator for chemistry problems.

Classes

BasicQuantumPhaseEstimationGroundStateCalculator	Class for calculating the ground state energy of a molecule using quantum phase estimation.
BayesianQuantumPhaseEstimationGroundStateCalculator	Class for calculating the ground state energy of a molecule using Bayesian quantum phase estimation.

class BasicQuantumPhaseEstimationGroundStateCalculator

Bases: object

Class for calculating the ground state energy of a molecule using quantum phase estimation.

__init__(quantum_phase_estimator: SecondQuantizationBasicQuantumPhaseEstimator, *, paired_electron_approximation: bool) → None

Initialize the molecular ground state energy calculator.

Parameters:

• quantum_phase_estimator (SecondQuantizationBasicQuantumPhaseEstimator) – The quantum phase estimation algorithm to use for the calculation.

• paired_electron_approximation (bool) – Whether to use the paired-electron approximation.

Return type:

None

calculate(problem: GeneralGroundStateProblem, initial_vqe_result: AdaptiveVqeGroundStateProblemCalculatorResult | None = None) → GroundStateProblemCalculatorResult

calculate(problem: ReactionPathProblem, initial_vqe_result: AdaptiveVqeReactionPathProblemCalculatorResult | None = None) → ReactionPathProblemCalculatorResult

Calculate the expectation value of the ground state energy of the given molecule/reaction.

Parameters:

• problem (RestrictedGroundStateProblem | LazyRestrictedGroundStateProblem | UnrestrictedGroundStateProblem | LazyUnrestrictedGroundStateProblem | RestrictedReactionPathProblem | UnrestrictedReactionPathProblem) – Ground state problem or reaction path problem to calculate energy for.

• initial_vqe_result (AdaptiveVqeGroundStateProblemCalculatorResult | AdaptiveVqeReactionPathProblemCalculatorResult | None) – Optional VQE result to use as the starting point for the calculation. For a GeneralGroundStateProblem this must be an AdaptiveVqeGroundStateProblemCalculatorResult, and for a ReactionPathProblem an AdaptiveVqeReactionPathProblemCalculatorResult.

Return type:

GroundStateProblemCalculatorResult | ReactionPathProblemCalculatorResult

class BayesianQuantumPhaseEstimationGroundStateCalculator

Bases: object

Class for calculating the ground state energy of a molecule using Bayesian quantum phase estimation.

__init__(quantum_phase_estimator: SecondQuantizationBayesianQuantumPhaseEstimation, *, paired_electron_approximation: bool) → None

Initialize the molecular ground state energy calculator.

Parameters:

• quantum_phase_estimator (SecondQuantizationBayesianQuantumPhaseEstimation) – The Bayesian quantum phase estimation algorithm to use for the calculation.

• paired_electron_approximation (bool) – Whether to use the paired-electron approximation.

Return type:

None

calculate(problem: GeneralGroundStateProblem, initial_vqe_result: AdaptiveVqeGroundStateProblemCalculatorResult | None = None) → GroundStateProblemCalculatorResult

calculate(problem: ReactionPathProblem, initial_vqe_result: AdaptiveVqeReactionPathProblemCalculatorResult | None = None) → ReactionPathProblemCalculatorResult

Calculate the expectation value of the ground state energy of the given molecule/reaction.

Parameters:

• problem (RestrictedGroundStateProblem | LazyRestrictedGroundStateProblem | UnrestrictedGroundStateProblem | LazyUnrestrictedGroundStateProblem | RestrictedReactionPathProblem | UnrestrictedReactionPathProblem) – Ground state problem or reaction path problem to calculate energy for.

• initial_vqe_result (AdaptiveVqeGroundStateProblemCalculatorResult | AdaptiveVqeReactionPathProblemCalculatorResult | None) – Optional VQE result to use as the starting point for the calculation. For a GeneralGroundStateProblem this must be an AdaptiveVqeGroundStateProblemCalculatorResult, and for a ReactionPathProblem an AdaptiveVqeReactionPathProblemCalculatorResult.

Return type:

GroundStateProblemCalculatorResult | ReactionPathProblemCalculatorResult