Template Class HamiltonianBase

• Defined in File Observables.hpp

Inheritance Relationships

Base Type

• public Pennylane::Observables::Observable< StateVectorT > (Template Class Observable)

Class Documentation

template<class StateVectorT>
class HamiltonianBase : public Pennylane::Observables::Observable<StateVectorT>

Base class for a general Hamiltonian representation as a sum of observables.

Template Parameters

StateVectorT – State vector class.

Public Types

using PrecisionT = typename StateVectorT::PrecisionT

Public Functions

template<typename T1, typename T2>
inline HamiltonianBase(T1 &&coeffs, T2 &&obs)

Create a Hamiltonian from coefficients and observables.

Parameters

• coeffs – Arguments to construct coefficients

• obs – Arguments to construct observables

inline virtual void applyInPlace(StateVectorT &sv) const override

Apply the observable to the given statevector in place.

inline virtual void applyInPlaceShots(StateVectorT &sv, std::vector<std::vector<PrecisionT>> &eigenValues, std::vector<std::size_t> &ob_wires) const override

Apply unitaries of an observable to the given statevector in place.

Parameters

• sv – Reference to StateVector object.

• eigenValues – Eigenvalues of an observable.

• ob_wires – Reference to a std::vector object which stores wires of the observable.

inline virtual auto getWires() const -> std::vector<std::size_t> override

Get the wires the observable applies to.

inline virtual auto getObsName() const -> std::string override

Get the name of the observable.

inline virtual auto getObs() const -> std::vector<std::shared_ptr<Observable<StateVectorT>>> override

Get the observable.

inline virtual auto getCoeffs() const -> std::vector<PrecisionT> override

Get the coefficients of the observable.

Public Static Functions

static inline auto create(std::initializer_list<PrecisionT> coeffs, std::initializer_list<std::shared_ptr<Observable<StateVectorT>>> obs) -> std::shared_ptr<HamiltonianBase<StateVectorT>>

Convenient wrapper for the constructor as the constructor does not convert the std::shared_ptr with a derived class correctly.

This function is useful as std::make_shared does not handle brace-enclosed initializer list correctly.

Parameters

• coeffs – Arguments to construct coefficients

• obs – Arguments to construct observables

Returns

std::shared_ptr<HamiltonianBase<StateVectorT>>

Protected Attributes

std::vector<PrecisionT> coeffs_

std::vector<std::shared_ptr<Observable<StateVectorT>>> obs_

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