Fix json serializer for NoiseModel class

CHANGELOG.rst

@@ -33,6 +33,7 @@ Fixed
 """""
 
 - Fixed incorrect parsing of some API hub URLs (#77).
+- Fixed noise model handling for remote simulators (#84).
 
 
 `0.1.1`_ - 2019-05-01

qiskit/providers/ibmq/utils.py

@@ -17,6 +17,31 @@
 from qiskit.qobj import QobjHeader
 
 
+def _serialize_noise_model(config):
+    """Traverse the dictionary looking for noise_model keys and apply
+       a transformation so it can be serialized.
+
+       Args:
+           config (dict): The dictionary to traverse
+
+       Returns:
+           dict: The transformed dictionary
+    """
+    for k, v in config.items():
+        if isinstance(config[k], dict):
+            _serialize_noise_model(config[k])
+        else:
+            if k == 'noise_model':
+                try:
+                    config[k] = v.as_dict(serializable=True)
+                except AttributeError:
+                    # if .as_dict() fails is probably because the noise_model
+                    # has been already transformed elsewhere
+                    pass
+
+    return config
+
+
 def update_qobj_config(qobj, backend_options=None, noise_model=None):
     """Update a Qobj configuration from options and noise model.
 
@@ -35,9 +60,12 @@ def update_qobj_config(qobj, backend_options=None, noise_model=None):
         for key, val in backend_options.items():
             config[key] = val
 
-    # Append noise model to configuration.
+    # Append noise model to configuration. Overwrites backend option
     if noise_model:
-        config['noise_model'] = noise_model.as_dict(serializable=True)
+        config['noise_model'] = noise_model
+
+    # Look for noise_models in the config, and try to transform them
+    config = _serialize_noise_model(config)
 
     # Update the Qobj configuration.
     qobj.config = QobjHeader.from_dict(config)