Class QMLExecutor

Class Documentation

class QMLExecutor

A class which handles executing and obtaining shots from a parametrised cicuit, as well as gradient calculations.

Public Functions

QMLExecutor(ParamCirc inputCirc, std::vector<double> initInputs, std::vector<double> initWeights)

Creates an executor for a defined parametrized circuit with initial specifications for inputs and variational parameters.

Parameters:

  • inputCirc – Parametrized circuit to be executed [qb::qml::ParamCirc]

  • initInputs – Inputs to initialise the execution with [std::vector<double>]

  • initWeights – Weights/variational gate parameters to initialise the execution with [std::vector<double>]

std::vector<double> constructFullParamVector()

Return full parameter vector, constructed from the defined input and weight parameter values.

void run()

Execute the circuit.

void runGradients()

Execute the circuit for gradient calculation (e.g. execute multiple +/- shifted circuits for the parameter-shift rule).

inline std::vector<double> getStats()

Obtain bitstring probabilities from the output buffer after running.

std::vector<std::vector<double>> getStatGradients()

Obtain the gradients of output probabilities w.r.t. the variational parameters.

inline void setInputParams(std::vector<double> inputs)

Manually set the input parameters for parametrized circuit execution.

inline void setWeights(std::vector<double> weights)

Manually set the variational/weight parameters for parametrized circuit execution.

inline void setCircuit(ParamCirc newCirc)

Manually set the parametrized circuit (qb::qml::ParamCirc) to be executed.

inline void setNumShots(std::size_t numShots)

Manually set the number of shots to run the circuit for during execution.

inline void setSeed(int seed)

Manually set the seed for the circuit executor.

inline std::vector<double> getInputParams()

Return the currently defined input parameter values.

inline std::vector<double> getWeights()

Return the currently defined variational parameter values.

inline ParamCirc getCircuit()

Return the currently defined parametrized circuit that is to be executed.

inline std::size_t getNumShots()

Return the currently defined number of shots.

inline int getSeed()

Return the currently defined seed.

inline std::shared_ptr<xacc::AcceleratorBuffer> getGradBuffer()

Return the gradient buffer which stores the gradient executions and shot results.

inline std::shared_ptr<xacc::AcceleratorBuffer> getBuffer()

Return the output buffer which stores the shot results from execution.

Public Members

std::string acc = "aer"

The currently defined accelerator (defaults to “aer”). Valid settings: “aer” | “tnqvm” | “qpp”.

Private Functions

std::vector<double> getStatsFromShots(std::map<std::string, int> shotsDict)
std::string gradientTypeToString()

Private Members

ParamCirc targetCircuit_
int seed_ = {-1}
bool seeded_ = {false}
std::size_t numShots_ = {1024}
std::shared_ptr<xacc::Accelerator> accPointer_{xacc::getAccelerator("aer", {{"shots", (int)numShots_}})}
std::vector<double> inputParamVals_
std::vector<double> weightParamVals_
std::shared_ptr<xacc::AcceleratorBuffer> outputBuffer_
std::shared_ptr<xacc::AcceleratorBuffer> gradientBuffer_
std::shared_ptr<xacc::Observable> observables_
GradientTypes gradientType_{GradientTypes::parameter_shift}
std::shared_ptr<xacc::AlgorithmGradientStrategy> gradientMethod_