Probabilities

Functions for non-destructively calculating the probabilities of measurement outcomes. More...

Functions
qreal	calcProbOfBasisState (Qureg qureg, qindex index)
qreal	calcProbOfMultiQubitOutcome (Qureg qureg, int *qubits, int *outcomes, int numQubits)
qreal	calcProbOfMultiQubitOutcome (Qureg qureg, std::vector< int > qubits, std::vector< int > outcomes)
qreal	calcProbOfQubitOutcome (Qureg qureg, int qubit, int outcome)
void	calcProbsOfAllMultiQubitOutcomes (qreal *outcomeProbs, Qureg qureg, int *qubits, int numQubits)
std::vector< qreal >	calcProbsOfAllMultiQubitOutcomes (Qureg qureg, std::vector< int > qubits)

Detailed Description

Functions for non-destructively calculating the probabilities of measurement outcomes.

Function Documentation

calcProbOfBasisState()

qreal calcProbOfBasisState	(	Qureg	qureg,
		qindex	index )

Note

Documentation for this function or struct is under construction!

Attention

This function's input validation has not yet been unit tested, so erroneous usage may produce unexpected output. Please use with caution!

Definition at line 224 of file calculations.cpp.

                                                      {
    validate_quregFields(qureg, __func__);
    validate_basisStateIndex(qureg, index, __func__);
 
    // |i><i| = ||(1+2^N)i>>
    if (qureg.isDensityMatrix)
        index *= 1 + powerOf2(qureg.numQubits);
 
    qcomp amp = localiser_statevec_getAmp(qureg, index);
    qreal prob = (qureg.isDensityMatrix)? 
        std::real(amp): 
        std::norm(amp);
 
    return prob;
}

Referenced by TEST_CASE().

calcProbOfMultiQubitOutcome() [1/2]

qreal calcProbOfMultiQubitOutcome	(	Qureg	qureg,
		int *	qubits,
		int *	outcomes,
		int	numQubits )

Note

Documentation for this function or struct is under construction!

Attention

This function's input validation has not yet been unit tested, so erroneous usage may produce unexpected output. Please use with caution!

Definition at line 251 of file calculations.cpp.

                                                                                          {
    validate_quregFields(qureg, __func__);
    validate_targets(qureg, qubits, numQubits, __func__);
    validate_measurementOutcomesAreValid(outcomes, numQubits, __func__);
 
    auto qubitVec = util_getVector(qubits, numQubits);
    auto outcomeVec = util_getVector(outcomes, numQubits);
 
    return (qureg.isDensityMatrix)?
        localiser_densmatr_calcProbOfMultiQubitOutcome(qureg, qubitVec, outcomeVec):
        localiser_statevec_calcProbOfMultiQubitOutcome(qureg, qubitVec, outcomeVec);
}

Referenced by applyForcedMultiQubitMeasurement(), calcProbOfMultiQubitOutcome(), calcProbOfQubitOutcome(), and TEST_CASE().

calcProbOfMultiQubitOutcome() [2/2]

qreal calcProbOfMultiQubitOutcome	(	Qureg	qureg,
		std::vector< int >	qubits,
		std::vector< int >	outcomes )

Warning

This function has not yet been unit tested and may contain bugs. Please use with caution!

Note

Documentation for this function or struct is under construction!

Attention

This function's input validation has not yet been unit tested, so erroneous usage may produce unexpected output. Please use with caution!

Remarks

This function is only available in C++.

Definition at line 418 of file calculations.cpp.

                                                                                         {
 
    // C interface discards individual sizes, so we validate
    validate_measurementOutcomesMatchTargets(qubits.size(), outcomes.size(), __func__);
 
    // but C function performs all other validation
    return calcProbOfMultiQubitOutcome(qureg, qubits.data(), outcomes.data(), qubits.size());
}

calcProbOfQubitOutcome()

qreal calcProbOfQubitOutcome	(	Qureg	qureg,
		int	qubit,
		int	outcome )

Note

Documentation for this function or struct is under construction!

Attention

This function's input validation has not yet been unit tested, so erroneous usage may produce unexpected output. Please use with caution!

Definition at line 241 of file calculations.cpp.

                                                                  {
    validate_quregFields(qureg, __func__);
    validate_target(qureg, qubit, __func__);
    validate_measurementOutcomeIsValid(outcome, __func__);
 
    int numQubits = 1;
    return calcProbOfMultiQubitOutcome(qureg, &qubit, &outcome, numQubits);
}

Referenced by applyForcedQubitMeasurement(), applyQubitMeasurementAndGetProb(), and TEST_CASE().

calcProbsOfAllMultiQubitOutcomes() [1/2]

void calcProbsOfAllMultiQubitOutcomes	(	qreal *	outcomeProbs,
		Qureg	qureg,
		int *	qubits,
		int	numQubits )

Note

Documentation for this function or struct is under construction!

Attention

This function's input validation has not yet been unit tested, so erroneous usage may produce unexpected output. Please use with caution!

Definition at line 265 of file calculations.cpp.

                                                                                                    {
    validate_quregFields(qureg, __func__);
    validate_targets(qureg, qubits, numQubits, __func__);
    validate_measurementOutcomesFitInGpuMem(qureg, numQubits, __func__);
 
    auto qubitVec = util_getVector(qubits, numQubits);
 
    (qureg.isDensityMatrix)?
        localiser_densmatr_calcProbsOfAllMultiQubitOutcomes(outcomeProbs, qureg, qubitVec):
        localiser_statevec_calcProbsOfAllMultiQubitOutcomes(outcomeProbs, qureg, qubitVec);
}

Referenced by applyMultiQubitMeasurementAndGetProb(), calcProbsOfAllMultiQubitOutcomes(), and TEST_CASE().

calcProbsOfAllMultiQubitOutcomes() [2/2]

std::vector< qreal > calcProbsOfAllMultiQubitOutcomes	(	Qureg	qureg,
		std::vector< int >	qubits )

Warning

This function has not yet been unit tested and may contain bugs. Please use with caution!

Note

Documentation for this function or struct is under construction!

Attention

This function's input validation has not yet been unit tested, so erroneous usage may produce unexpected output. Please use with caution!

Remarks

This function is only available in C++.

Definition at line 428 of file calculations.cpp.

                                                                                {
 
    // allocate temp vector, and validate successful (since it's exponentially large!)
    vector<qreal> out;
    qindex numOut = powerOf2(qubits.size());
    auto callback = [&]() { validate_tempAllocSucceeded(false, numOut, sizeof(qreal), __func__); };
    util_tryAllocVector(out, numOut, callback);
 
    calcProbsOfAllMultiQubitOutcomes(out.data(), qureg, qubits.data(), qubits.size());
    return out;
}