QFT

Functions for applying the Quantum Fourier Transform. More...

Functions
void	applyFullQuantumFourierTransform (Qureg qureg)
void	applyQuantumFourierTransform (Qureg qureg, int *targets, int numTargets)

Detailed Description

Functions for applying the Quantum Fourier Transform.

Function Documentation

applyFullQuantumFourierTransform()

void applyFullQuantumFourierTransform

(

Qureg

qureg

)

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 1760 of file operations.cpp.

                                                   {
    validate_quregFields(qureg, __func__);
 
    // tiny; no need to validate alloc
    vector<int> targets(qureg.numQubits);
    for (size_t i=0; i<targets.size(); i++)
        targets[i] = i;
 
    applyQuantumFourierTransform(qureg, targets.data(), targets.size());
}

Referenced by TEST_CASE().

applyQuantumFourierTransform()

void applyQuantumFourierTransform	(	Qureg	qureg,
		int *	targets,
		int	numTargets )

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 1739 of file operations.cpp.

                                                                             {
    validate_quregFields(qureg, __func__);
    validate_targets(qureg, targets, numTargets, __func__);
 
    /// @todo
    /// change this placeholder implementation to the bespoke, optimised routine,
    /// wherein each contiguous controlled-phase gate is merged
 
    for (int n=numTargets-1; n>=0; n--) {
        applyHadamard(qureg, targets[n]);
        for (int m=0; m<n; m++) {
            qreal arg = const_PI / powerOf2(m+1);
            applyTwoQubitPhaseShift(qureg, targets[n], targets[n-m-1], arg);
        }
    }
 
    int mid = numTargets/2; // floors
    for (int n=0; n<mid; n++)
        applySwap(qureg, targets[n], targets[numTargets-1-n]);
}

Referenced by applyFullQuantumFourierTransform(), applyQuantumFourierTransform(), and TEST_CASE().