Deprecate 'id' instructions on IBM Quantum hardware backends.

qiskit/providers/ibmq/ibmqbackend.py

@@ -20,7 +20,8 @@
 from datetime import datetime as python_datetime
 
 from qiskit.compiler import assemble
-from qiskit.circuit import QuantumCircuit, Parameter
+from qiskit.circuit import QuantumCircuit, Parameter, Delay
+from qiskit.circuit.duration import duration_in_dt
 from qiskit.pulse import Schedule, LoConfig
 from qiskit.pulse.channels import PulseChannel
 from qiskit.qobj import QasmQobj, PulseQobj, validate_qobj_against_schema
@@ -102,6 +103,7 @@ class IBMQBackend(Backend):
     """
 
     qobj_warning_issued = False
+    id_warning_issued = False
 
     def __init__(
             self,
@@ -286,6 +288,9 @@ def run(
                 "'use_measure_esp' is unset or set to 'False'."
             )
 
+        if not self.configuration().simulator:
+            self._deprecate_id_instruction(circuits)
+
         if isinstance(circuits, (QasmQobj, PulseQobj)):
             if not self.qobj_warning_issued:
                 warnings.warn("Passing a Qobj to Backend.run is deprecated and will "
@@ -746,6 +751,92 @@ def __repr__(self) -> str:
         return "<{}('{}') from IBMQ({})>".format(
             self.__class__.__name__, self.name(), credentials_info)
 
+    def _deprecate_id_instruction(
+            self,
+            circuits: Union[QasmQobj, PulseQobj, QuantumCircuit, Schedule,
+                            List[Union[QuantumCircuit, Schedule]]]
+    ) -> None:
+        """Raise a DeprecationWarning if any circuit contains an 'id' instruction.
+
+        Additionally, if 'delay' is a 'supported_instruction', replace each 'id'
+        instruction (in-place) with the equivalent ('sx'-length) 'delay' instruction.
+
+        Args:
+            circuits: The individual or list of :class:`~qiskit.circuits.QuantumCircuit` or
+                :class:`~qiskit.pulse.Schedule` objects passed to
+                :meth:`IBMQBackend.run()<IBMQBackend.run>`. Modified in-place.
+
+        Returns:
+            None
+        """
+
+        if isinstance(circuits, PulseQobj):
+            return
+
+        id_support = 'id' in getattr(self.configuration(), 'basis_gates', [])
+        delay_support = 'delay' in getattr(self.configuration(), 'supported_instructions', [])
+
+        if not delay_support:
+            return
+
+        if isinstance(circuits, QasmQobj):
+            circuit_has_id = any(instr.name == 'id'
+                                 for experiment in circuits.experiments
+                                 for instr in experiment.instructions)
+        else:
+            if not isinstance(circuits, List):
+                circuits = [circuits]
+
+            circuit_has_id = any(instr.name == 'id'
+                                 for circuit in circuits
+                                 if isinstance(circuit, QuantumCircuit)
+                                 for instr, qargs, cargs in circuit.data)
+
+        if not circuit_has_id:
+            return
+
+        if not self.id_warning_issued:
+            if id_support and delay_support:
+                warnings.warn("Support for the 'id' instruction has been deprecated "
+                              "from IBM hardware backends. Any 'id' instructions "
+                              "will be replaced with their equivalent 'delay' instruction. "
+                              "Please use the 'delay' instruction instead.", DeprecationWarning,
+                              stacklevel=4)
+            else:
+                warnings.warn("Support for the 'id' instruction has been removed "
+                              "from IBM hardware backends. Any 'id' instructions "
+                              "will be replaced with their equivalent 'delay' instruction. "
+                              "Please use the 'delay' instruction instead.", DeprecationWarning,
+                              stacklevel=4)
+
+            self.id_warning_issued = True
+
+        dt_in_s = self.configuration().dt
+
+        if isinstance(circuits, QasmQobj):
+            for experiment in circuits.experiments:
+                for instr in experiment.instructions:
+                    if instr.name == 'id':
+                        sx_duration = self.properties().gate_length('sx', instr.qubits[0])
+                        sx_duration_in_dt = duration_in_dt(sx_duration, dt_in_s)
+
+                        instr.name = 'delay'
+                        instr.params = [sx_duration_in_dt]
+        else:
+            for circuit in circuits:
+                if isinstance(circuit, Schedule):
+                    continue
+
+                for idx, (instr, qargs, cargs) in enumerate(circuit.data):
+                    if instr.name == 'id':
+
+                        sx_duration = self.properties().gate_length('sx', qargs[0].index)
+                        sx_duration_in_dt = duration_in_dt(sx_duration, dt_in_s)
+
+                        delay_instr = Delay(sx_duration_in_dt)
+
+                        circuit.data[idx] = (delay_instr, qargs, cargs)
+
 
 class IBMQSimulator(IBMQBackend):
     """Backend class interfacing with an IBM Quantum Experience simulator."""

releasenotes/notes/deprecate-hardware-id-instructions-5166323103eefdc4.yaml

@@ -0,0 +1,11 @@
+---
+deprecations:
+  - |
+    The `id` instruction has been deprecated on IBM hardware
+    backends. Instead, please use the `delay` instruction which
+    implements variable-length delays, specified in units of
+    `dt`. When running a circuit containing an `id` instruction,
+    a warning will be raised on job submission and any `id`
+    instructions in the job will be automatically replaced with their
+    equivalent `delay` instruction.
+

test/ibmq/test_ibmq_backend.py

@@ -16,8 +16,10 @@
 from datetime import timedelta, datetime
 import warnings
 from unittest import SkipTest
+from unittest.mock import patch
 
-from qiskit import transpile, assemble
+from qiskit import QuantumCircuit, transpile, assemble
+from qiskit.providers.models import QasmBackendConfiguration
 from qiskit.test.reference_circuits import ReferenceCircuits
 from qiskit.providers.ibmq.ibmqbackend import IBMQBackend
 from qiskit.providers.ibmq.ibmqbackendservice import IBMQBackendService
@@ -176,6 +178,37 @@ def test_sim_backend_options(self):
         self.assertTrue(qobj.config.memory)
         self.assertEqual(qobj.config.foo, 'foo')
 
+    def test_deprecate_id_instruction(self):
+        """Test replacement of 'id' Instructions with 'Delay' instructions."""
+
+        circuit_with_id = QuantumCircuit(2)
+        circuit_with_id.id(0)
+        circuit_with_id.id(0)
+        circuit_with_id.id(1)
+
+        config = QasmBackendConfiguration(
+            basis_gates=['id'],
+            supported_instructions=['delay'],
+            dt=0.25,
+            backend_name='test',
+            backend_version=0.0,
+            n_qubits=1,
+            gates=[],
+            local=False,
+            simulator=False,
+            conditional=False,
+            open_pulse=False,
+            memory=False,
+            max_shots=1,
+            coupling_map=None,
+        )
+
+        with patch.object(self.backend, 'configuration', return_value=config):
+            with self.assertWarnsRegex(DeprecationWarning, r"'id' instruction"):
+                self.backend._deprecate_id_instruction(circuit_with_id)
+
+            self.assertEqual(circuit_with_id.count_ops(), {'delay': 3})
+
 
 class TestIBMQBackendService(IBMQTestCase):
     """Test ibmqbackendservice module."""