Update example and documentation

docs/sphinx/examples/cpp/basics/noise_modeling.cpp

@@ -39,14 +39,18 @@ int main() {
                               {-0.05773502691896258, 0.0}});
 
   // Create the noise model
-  cudaq::noise_model noise;
+  auto noise = std::make_shared<cudaq::noise_model>();
   // Add the Kraus channel to the x operation on qubit 0.
-  noise.add_channel<cudaq::types::x>({0}, depol);
+  noise->add_channel<cudaq::types::x>({0}, depol);
 
   // Set the noise model
   cudaq::set_noise(noise);
 
   // Run the noisy simulation
   counts = cudaq::sample(xgate);
   counts.dump();
+
+  // Unset the noise model when done. This is not necessary in this case but is
+  // good practice in order to not interfere with future simulations.
+  cudaq::unset_noise();
 }

docs/sphinx/using/advanced/_noise.rst

@@ -45,7 +45,7 @@ template type is the quantum operation the channel applies to (e.g. :code:`model
 apply to the simulated state via a :code:`noise_model::get_channel(...)` call. 
 
 Noise models can be constructed via the :code:`cudaq::noise_model` and specified for 
-execution via a public :code:`cudaq::set_noise(cudaq::noise_model&)` function. This function 
+execution via a public :code:`cudaq::set_noise(std::shared_ptr<cudaq::noise_model>)` function. This function 
 should forward the :code:`noise_model` to the current :code:`quantum_platform` which can attach it 
 to the current :code:`ExecutionContext` and retrieved by backend simulators.