Function applyMultiStateControlledRotateAroundAxis

quest/src/api/operations.cpp:1198–1218

}

void applyMultiStateControlledRotateAroundAxis(Qureg qureg, int* ctrls, int* states, int numCtrls, int targ, qreal angle, qreal axisX, qreal axisY, qreal axisZ) {
    validate_quregFields(qureg, __func__);
    validate_controlsAndTarget(qureg, ctrls, numCtrls, targ, __func__);
    validate_controlStates(states, numCtrls, __func__); // permits states==nullptr
    validate_rotationAxisNotZeroVector(axisX, axisY, axisZ, __func__);

    // defer division of vector norm to improve numerical accuracy
    qreal norm = std::sqrt(std::pow(axisX,2) + std::pow(axisY,2) + std::pow(axisZ,2)); // != 0

    // treat as generic 1-qubit matrix
    qreal c = std::cos(angle/2);
    qreal s = std::sin(angle/2);
    qcomp u11 = c - (s * axisZ * 1_i) / norm;
    qcomp u12 =   - (s * (axisY + axisX * 1_i)) / norm;
    qcomp u21 =     (s * (axisY - axisX * 1_i)) / norm;
    qcomp u22 = c + (s * axisZ * 1_i) / norm;
    auto matr = getCompMatr1({{u11,u12},{u21,u22}});

    // harmlessly re-validates, and checks unitarity of matr
    applyMultiStateControlledCompMatr1(qureg, ctrls, states, numCtrls, targ, matr);
}

} // end de-mangler