Count number of incorrect results in the graph state backend

[Naphann]

In the error tracking backend (tracking deviations from Phi+ state Bell pairs), we have a way to count how many erroneous Bell pairs we got when performing tomography.

quisp/quisp/modules/QRSA/HardwareMonitor/HardwareMonitor.cc

Lines 414 to 424 in 79d417f

	tomography_stats << this_node->getFullName() << "<-->QuantumChannel{cost=" << link_cost << ";distance=" << dis << "km;fidelity=" << fidelity
	<< ";bellpair_per_sec=" << tomography_runningtime_holder[qnic][partner_address].Bellpair_per_sec
	<< ";tomography_time=" << tomography_runningtime_holder[qnic][partner_address].tomography_time
	<< ";tomography_measurements=" << tomography_runningtime_holder[qnic][partner_address].tomography_measurements << ";actual_meas=" << meas_total
	<< "; GOD_clean_pair_total=" << GOD_clean_pair_total << "; GOD_X_pair_total=" << GOD_X_pair_total << "; GOD_Y_pair_total=" << GOD_Y_pair_total
	<< "; GOD_Z_pair_total=" << GOD_Z_pair_total << ";}<-->" << partner_node->getFullName() << "; F=" << fidelity << "; X=" << Xerr_rate << "; Z=" << Zerr_rate
	<< "; Y=" << Yerr_rate << endl;
	// this is a temporary implementation so that the e2e-test can read fidelity and error rates
	std::cout << this_node->getFullName() << "<-->QuantumChannel{cost=" << link_cost << ";distance=" << dis << "km;fidelity=" << fidelity
	<< ";bellpair_per_sec=" << tomography_runningtime_holder[qnic][partner_address].Bellpair_per_sec << ";}<-->" << partner_node->getFullName()
	<< "; Fidelity=" << fidelity << "; Xerror=" << Xerr_rate << "; Zerror=" << Zerr_rate << "; Yerror=" << Yerr_rate << endl;

Right now we only return clean_pair from graph state backend (as shown below)

[[deprecated]] MeasurementOutcome GraphStateQubit::measureDensityIndependent() {
  auto rand = backend->dblrand();
  MeasurementOutcome o;
  if (rand < ((double)1 / (double)3)) {
    o.basis = 'X';
    o.outcome_is_plus = this->localMeasureX() == EigenvalueResult::PLUS_ONE ? true : false;
  } else if (rand < ((double)2 / (double)3)) {
    o.basis = 'Z';
    o.outcome_is_plus = this->localMeasureZ() == EigenvalueResult::PLUS_ONE ? true : false;
  } else {
    o.basis = 'Y';
    o.outcome_is_plus = this->localMeasureY() == EigenvalueResult::PLUS_ONE ? true : false;
  }
  // the pi vector should be always [1,0,0,0,0,0], just for compatibility
  o.GOD_clean = 'F';
  return o;
}