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Template Class AdjointJacobianBase

Class Documentation

template<class StateVectorT, class Derived>
class AdjointJacobianBase

Adjoint Jacobian evaluator following the method of arXiv:2009.02823.

This class uses the Curiously Recurring Template Pattern (CRTP) to provide static polymorphism for the adjoint differentiation method. To use this class, derive from it passing your class as the Derived template parameter:

class LThunderAdjointJacobian : public
AdjointJacobianBase<LThunderStateVector, LThunderAdjointJacobian> { public:
    // Must implement this method as required by the base class
    void adjointJacobian(std::span<PrecisionT> jac,
                         const JacobianData<StateVectorT> &jd,
                         const StateVectorT &ref_data,
                         bool apply_operations) {
        // Your implementation here
    }
};
Template Parameters

  • StateVectorT – State vector type.

  • Derived – The derived class implementing the concrete adjointJacobian method.

Public Functions

virtual ~AdjointJacobianBase() = default

Protected Types

using ComplexT = typename StateVectorT::ComplexT
using PrecisionT = typename StateVectorT::PrecisionT

Protected Functions

AdjointJacobianBase() = default
AdjointJacobianBase(const AdjointJacobianBase&) = default
AdjointJacobianBase(AdjointJacobianBase&&) noexcept = default
AdjointJacobianBase &operator=(const AdjointJacobianBase&) = default
AdjointJacobianBase &operator=(AdjointJacobianBase&&) noexcept = default
template<class UpdatedStateVectorT>
inline void applyOperations(UpdatedStateVectorT &state, const OpsData<StateVectorT> &operations, bool adj = false)

Apply all operations from given OpsData<StateVectorT> object to UpdatedStateVectorT.

Template Parameters

UpdatedStateVectorT –

Parameters

  • state – Statevector to be updated.

  • operations – Operations to apply.

  • adj – Take the adjoint of the given operations.

template<class UpdatedStateVectorT>
inline void applyOperationAdj(UpdatedStateVectorT &state, const OpsData<StateVectorT> &operations, std::size_t op_idx)

Apply the adjoint indexed operation from OpsData<StateVectorT> object to UpdatedStateVectorT.

Template Parameters

UpdatedStateVectorT – updated state vector type.

Parameters

  • state – Statevector to be updated.

  • operations – Operations to apply.

  • op_idx – Adjointed operation index to apply.

inline void applyOperationsAdj(std::vector<StateVectorT> &states, const OpsData<StateVectorT> &operations, std::size_t op_idx)

Apply the adjoint indexed operation from several OpsData<StateVectorT> objects to UpdatedStateVectorT objects.

Parameters

  • states – Vector of all statevectors; 1 per observable

  • operations – Operations list.

  • op_idx – Index of given operation within operations list to take adjoint of.

inline auto applyGenerator(StateVectorT &sv, const std::string &op_name, const std::vector<std::size_t> &wires, const bool adj) -> PrecisionT

Applies the gate generator for a given parametric gate. Returns the associated scaling coefficient.

Parameters

  • sv – Statevector data to operate upon.

  • op_name – Name of parametric gate.

  • wires – Wires to operate upon.

  • adj – Indicate whether to take the adjoint of the operation.

Returns

PrecisionT Generator scaling coefficient.

inline auto applyGenerator(StateVectorT &sv, const std::string &op_name, const std::vector<std::size_t> &controlled_wires, const std::vector<bool> &controlled_values, const std::vector<std::size_t> &wires, const bool adj) -> PrecisionT

Applies the gate generator for a given parametric gate. Returns the associated scaling coefficient.

Parameters

  • sv – Statevector data to operate upon.

  • op_name – Name of parametric gate.

  • controlled_wires – Control wires.

  • controlled_values – Control values (false or true).

  • wires – Wires to operate upon.

  • adj – Indicate whether to take the adjoint of the operation.

Returns

PrecisionT Generator scaling coefficient.

inline void applyObservable(StateVectorT &state, const Observable<StateVectorT> &observable)

Apply a given Observable<StateVectorT> object to StateVectorT.

Parameters

  • state – Statevector to be updated.

  • observable – Observable to apply.

inline void applyObservables(std::vector<StateVectorT> &states, const StateVectorT &reference_state, const std::vector<std::shared_ptr<Observable<StateVectorT>>> &observables)

Apply several Observable<StateVectorT> object. to StateVectorT objects.

Parameters

  • states – Vector of statevector copies, one per observable.

  • reference_state – Reference statevector

  • observables – Vector of observables to apply to each statevector.

inline void adjointJacobian(std::span<PrecisionT> jac, const JacobianData<StateVectorT> &jd, const StateVectorT &ref_data = {0}, bool apply_operations = false)

Calculates the statevector’s Jacobian for the selected set of parametric gates.

Parameters

  • jac – Preallocated vector for Jacobian data results.

  • jd – JacobianData represents the QuantumTape to differentiate.

  • apply_operations – Indicate whether to apply operations to tape.psi prior to calculation.

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