Extended stabilizer simulator no longer shares RngEngine amongst stat…

…es when ops are applied in parallel
Qiskit · Nov 7, 2023 · d693556 · d693556
1 parent e31ff65
commit d693556
Showing 1 changed file with 8 additions and 1 deletion.
diff --git a/src/simulators/extended_stabilizer/extended_stabilizer_state.hpp b/src/simulators/extended_stabilizer/extended_stabilizer_state.hpp
@@ -463,17 +463,24 @@ template <typename InputIterator>
 void State::apply_ops_parallel(InputIterator first, InputIterator last,
                                ExperimentResult &result, RngEngine &rng) {
   const int_t NUM_STATES = BaseState::qreg_.get_num_states();
+
+  std::vector<size_t> rng_seeds(NUM_STATES);
+  for (int_t i = 0; i < NUM_STATES; i++) {
+    rng_seeds[i] = size_t(rng.rand_int(0ULL, 18446744073709551615ULL));
+  }
+
 #pragma omp parallel for if (BaseState::qreg_.check_omp_threshold() &&         \
                              BaseState::threads_ > 1)                          \
     num_threads(BaseState::threads_)
   for (int_t i = 0; i < NUM_STATES; i++) {
     if (!BaseState::qreg_.check_eps(i)) {
       continue;
     }
+    RngEngine local_rng(rng_seeds[i]);
     for (auto it = first; it != last; it++) {
       switch (it->type) {
       case Operations::OpType::gate:
-        apply_gate(*it, rng, i);
+        apply_gate(*it, local_rng, i);
         break;
       case Operations::OpType::barrier:
       case Operations::OpType::qerror_loc: