Add apply_initialize to AerState (#2196)

* Add apply_initialize to AerState, move initialize from BASIS_GATES to _CUSTOM_INSTR

* add custom instructions to evelve_instruction

* format

* fix custom instructions

* fix custom instructions

qiskit_aer/backends/aer_simulator.py

@@ -523,6 +523,7 @@ class AerSimulator(AerBackend):
                 "while_loop",
                 "break_loop",
                 "continue_loop",
+                "initialize",
                 "reset",
                 "switch_case",
                 "delay",
@@ -575,6 +576,7 @@ class AerSimulator(AerBackend):
                 "while_loop",
                 "break_loop",
                 "continue_loop",
+                "initialize",
                 "reset",
                 "switch_case",
                 "delay",
@@ -655,6 +657,7 @@ class AerSimulator(AerBackend):
                 "save_statevector_dict",
                 "set_statevector",
                 "set_density_matrix",
+                "initialize",
                 "reset",
                 "switch_case",
                 "delay",

qiskit_aer/backends/backend_utils.py

@@ -113,7 +113,6 @@
             "unitary",
             "diagonal",
             "multiplexer",
-            "initialize",
             "pauli",
             "mcx_gray",
             "ecr",
@@ -197,7 +196,6 @@
             "csx",
             "cswap",
             "diagonal",
-            "initialize",
             "ecr",
             "store",
         ]
@@ -414,7 +412,6 @@
             "unitary",
             "diagonal",
             "multiplexer",
-            "initialize",
             "pauli",
             "mcx_gray",
             "ecr",

qiskit_aer/quantum_info/states/aer_densitymatrix.py

@@ -241,6 +241,7 @@ def _from_instruction(inst, init_data, configs):
             aer_state.configure(config_key, config_value)
 
         basis_gates = BASIS_GATES["density_matrix"]
+        custom_insts = ["reset", "kraus", "barrier"]
 
         aer_state.allocate_qubits(inst.num_qubits)
         num_qubits = inst.num_qubits
@@ -254,9 +255,13 @@ def _from_instruction(inst, init_data, configs):
             aer_state.apply_global_phase(inst.global_phase)
 
         if isinstance(inst, QuantumCircuit):
-            AerStatevector._aer_evolve_circuit(aer_state, inst, range(num_qubits), basis_gates)
+            AerStatevector._aer_evolve_circuit(
+                aer_state, inst, range(num_qubits), basis_gates, custom_insts
+            )
         else:
-            AerStatevector._aer_evolve_instruction(aer_state, inst, range(num_qubits), basis_gates)
+            AerStatevector._aer_evolve_instruction(
+                aer_state, inst, range(num_qubits), basis_gates, custom_insts
+            )
 
         return aer_state.move_to_ndarray(), aer_state
 

qiskit_aer/quantum_info/states/aer_state.py

@@ -468,6 +468,13 @@ def apply_measure(self, qubits):
         # measure and update state
         return self._native_state.apply_measure(qubits)
 
+    def apply_initialize(self, qubits, vec):
+        """apply an initialize operation."""
+        self._assert_allocated_or_mapped()
+        self._assert_in_allocated_qubits(qubits)
+        # update state
+        return self._native_state.apply_initialize(qubits, vec)
+
     def apply_reset(self, qubits):
         """apply a reset operation."""
         self._assert_allocated_or_mapped()

qiskit_aer/quantum_info/states/aer_statevector.py

@@ -175,6 +175,9 @@ def _from_instruction(inst, init_data, configs):
             aer_state.configure("method", method)
 
         basis_gates = BASIS_GATES[method]
+        custom_insts = ["reset", "kraus", "barrier"]
+        if method == "statevector":
+            custom_insts.append("initialize")
 
         aer_state.allocate_qubits(inst.num_qubits)
         num_qubits = inst.num_qubits
@@ -188,14 +191,18 @@ def _from_instruction(inst, init_data, configs):
             aer_state.apply_global_phase(inst.global_phase)
 
         if isinstance(inst, QuantumCircuit):
-            AerStatevector._aer_evolve_circuit(aer_state, inst, range(num_qubits), basis_gates)
+            AerStatevector._aer_evolve_circuit(
+                aer_state, inst, range(num_qubits), basis_gates, custom_insts
+            )
         else:
-            AerStatevector._aer_evolve_instruction(aer_state, inst, range(num_qubits), basis_gates)
+            AerStatevector._aer_evolve_instruction(
+                aer_state, inst, range(num_qubits), basis_gates, custom_insts
+            )
 
         return aer_state.move_to_ndarray(), aer_state
 
     @staticmethod
-    def _aer_evolve_circuit(aer_state, circuit, qubits, basis_gates=None):
+    def _aer_evolve_circuit(aer_state, circuit, qubits, basis_gates=None, custom_insts=None):
         """Apply circuit into aer_state"""
         for instruction in circuit.data:
             if instruction.clbits:
@@ -209,10 +216,11 @@ def _aer_evolve_circuit(aer_state, circuit, qubits, basis_gates=None):
                 inst,
                 [qubits[circuit.find_bit(qarg).index] for qarg in qargs],
                 basis_gates,
+                custom_insts,
             )
 
     @staticmethod
-    def _aer_evolve_instruction(aer_state, inst, qubits, basis_gates=None):
+    def _aer_evolve_instruction(aer_state, inst, qubits, basis_gates=None, custom_insts=None):
         """Apply instruction into aer_state"""
 
         params = inst.params
@@ -260,20 +268,27 @@ def _aer_evolve_instruction(aer_state, inst, qubits, basis_gates=None):
                 pass
             else:
                 applied = False
-        elif inst.name == "reset":
-            aer_state.apply_reset(qubits)
-        elif inst.name == "kraus":
-            aer_state.apply_kraus(qubits, inst.params)
-        elif inst.name == "barrier":
-            pass
+        elif custom_insts and inst.name in custom_insts:
+            if inst.name == "initialize":
+                aer_state.apply_initialize(qubits, inst.params)
+            elif inst.name == "reset":
+                aer_state.apply_reset(qubits)
+            elif inst.name == "kraus":
+                aer_state.apply_kraus(qubits, inst.params)
+            elif inst.name == "barrier":
+                pass
+            else:
+                applied = False
         else:
             applied = False
 
         if not applied:
             definition = inst.definition
             if definition is inst or definition is None:
                 raise AerError("cannot decompose " + inst.name)
-            AerStatevector._aer_evolve_circuit(aer_state, definition, qubits, basis_gates)
+            AerStatevector._aer_evolve_circuit(
+                aer_state, definition, qubits, basis_gates, custom_insts
+            )
 
     @classmethod
     def from_label(cls, label):