Add M3 mitigation to estimator (Qiskit#71)

* add M3 mitigation * clarify no mitigation case
blakejohnson · Oct 8, 2021 · 5d6c26e · 5d6c26e
1 parent 1e57ac2
commit 5d6c26e
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Showing 2 changed files with 22 additions and 6 deletions.
diff --git a/runtime/estimator.json b/runtime/estimator.json
@@ -9,6 +9,7 @@
     {"name": "parameters", "description": "The parameters to be bound.", "type": "Union[list[float], list[list[float]]]", "required": false},
     {"name": "class_name", "description": "The name of the evaluator class.", "type": "str", "required": false},
     {"name": "transpile_options", "description": "Options for transpile.", "type": "dict", "required": false},
-    {"name": "run_options", "description": "Options for backend.run.", "type": "dict", "required": false}
+    {"name": "run_options", "description": "Options for backend run.", "type": "dict", "required": false},
+    {"name": "measurement_error_mitigation", "description": "Whether to apply measurement error mitigation. Default is False.", "type": "bool", "required": false}
   ]
 }
diff --git a/runtime/estimator.py b/runtime/estimator.py
@@ -1,11 +1,12 @@
-import numpy as np
 from dataclasses import asdict
 
+import numpy as np
+from mthree.utils import final_measurement_mapping
+from qiskit.evaluators.backends import ReadoutErrorMitigation
 from qiskit.quantum_info import SparsePauliOp
 
 
 def main(backend, user_messenger, **kwargs):
-
     state = kwargs.pop("state")
     observable = kwargs.pop("observable")
     if isinstance(observable, list):
@@ -14,11 +15,28 @@ def main(backend, user_messenger, **kwargs):
     class_name = kwargs.pop("class_name", "PauliExpectationValue")
     transpile_options = kwargs.pop("transpile_options", {})
     run_options = kwargs.pop("run_options", {})
+    measurement_error_mitigation = kwargs.pop("measurement_error_mitigation", False)
 
     try:
         if class_name == "PauliExpectationValue":
             from qiskit.evaluators import PauliExpectationValue as Evaluator
+
+            if measurement_error_mitigation:
+                expval = Evaluator(state, observable, backend)
+                expval.set_transpile_options(**transpile_options)
+                mapping = final_measurement_mapping(expval.transpiled_circuits[0])
+                backend = ReadoutErrorMitigation(
+                    backend=backend,
+                    mitigation="mthree",
+                    refresh=1800,  # refresh the calibration data every 1800 seconds
+                    shots=8192,  # use M3's default shot number
+                    qubits=list(mapping),
+                )
+            else:
+                # use backend as is
+                pass
         elif class_name == "ExactExpectationValue":
+            # Note: ExactExpectationValue works only with Aer backend
             from qiskit.evaluators import ExactExpectationValue as Evaluator
     except ModuleNotFoundError:
         raise RuntimeError("You are not authorized to use this program.")
@@ -28,9 +46,6 @@ def main(backend, user_messenger, **kwargs):
     expval.set_run_options(**run_options)
     result = expval.evaluate(parameters)
 
-    # for debug
-    # print(result)
-
     ret = {
         key: val.tolist() if isinstance(val, np.ndarray) else val
         for key, val in asdict(result).items()