Function createMyObservable

examples/extended/dynamics.cpp:76–93

 */

PauliStrSum createMyObservable(int numQubits) {

    // we prepare a weighted sum of alternating Paulis
    // upon each qubit, i.e. 1 X0 + 2 Y1 + 3 Z2 + 1 X3 + ...
    // where the coefficients are real such that the
    // output observable is Hermitian.

    vector<PauliStr> strings(numQubits);
    vector<qcomp> coeffs(numQubits);

    for (int i=0; i<numQubits; i++) {
        strings[i] = getPauliStr({"XYZ"[i%3]}, {i});
        coeffs[i] = getQcomp(i%4 + 1, 0);
    }

    // must be freed by caller
    return createPauliStrSum(strings, coeffs);
}