Handle gates with ctrl_stete=0 (#2148)

* handle cx gate with ctrl_stete=0

* add handling *_o0, add test for cx_o0

* format

* fix test

* fix test

* fix test cx

* fix to handle multiple control states

* fix ctrl_state

* format

* resolve conflict again

* fix aer_compiler

qiskit_aer/backends/aer_compiler.py

@@ -812,18 +812,43 @@ def _assemble_op(
 
     aer_cond_expr = conditional_expr.accept(_AssembleExprImpl(circ)) if conditional_expr else None
 
+    # check if there is ctrl_state option
+    ctrl_state_pos = name.find("_o")
+    if ctrl_state_pos > 0:
+        gate_name = name[0:ctrl_state_pos]
+    else:
+        gate_name = name
+
     num_of_aer_ops = 1
     # fmt: off
-    if basis_gates is None and name in {
+    if (gate_name in {
         "ccx", "ccz", "cp", "cswap", "csx", "cx", "cy", "cz", "delay", "ecr", "h",
         "id", "mcp", "mcphase", "mcr", "mcrx", "mcry", "mcrz", "mcswap", "mcsx",
         "mcu", "mcu1", "mcu2", "mcu3", "mcx", "mcx_gray", "mcy", "mcz", "p", "r",
         "rx", "rxx", "ry", "ryy", "rz", "rzx", "rzz", "s", "sdg", "swap", "sx", "sxdg",
         "t", "tdg", "u", "x", "y", "z", "u1", "u2", "u3", "cu", "cu1", "cu2", "cu3",
         "crx", "cry", "crz",
-    }:
-        aer_circ.gate(name, qubits, params, [], conditional_reg, aer_cond_expr,
-                      label if label else name)
+    }) and (basis_gates is None or gate_name in basis_gates):
+        if ctrl_state_pos > 0:
+            # Add x gates for ctrl qubits which state=0
+            ctrl_state = int(name[ctrl_state_pos+2:len(name)])
+            for i in range(len(qubits)):
+                if (ctrl_state >> i) & 1 == 0:
+                    qubits_i = [qubits[len(qubits) - 1 - i]]
+                    aer_circ.gate("x", qubits_i, params, [], conditional_reg, aer_cond_expr,
+                                  label if label else "x")
+                    num_of_aer_ops += 1
+            aer_circ.gate(gate_name, qubits, params, [], conditional_reg, aer_cond_expr,
+                          label if label else gate_name)
+            for i in range(len(qubits)):
+                if (ctrl_state >> i) & 1 == 0:
+                    qubits_i = [qubits[len(qubits) - 1 - i]]
+                    aer_circ.gate("x", qubits_i, params, [], conditional_reg, aer_cond_expr,
+                                  label if label else "x")
+                    num_of_aer_ops += 1
+        else:
+            aer_circ.gate(name, qubits, params, [], conditional_reg, aer_cond_expr,
+                          label if label else name)
     elif name == "measure":
         if is_conditional:
             aer_circ.measure(qubits, clbits, clbits)
@@ -915,9 +940,6 @@ def _assemble_op(
         aer_circ.mark(qubits, params)
     elif name == "qerror_loc":
         aer_circ.set_qerror_loc(qubits, label if label else name, conditional_reg, aer_cond_expr)
-    elif basis_gates is not None and name in basis_gates:
-        aer_circ.gate(name, qubits, params, [], conditional_reg, aer_cond_expr,
-                      label if label else name)
     elif name in ("for_loop", "while_loop", "if_else"):
         raise AerError(
             "control-flow instructions must be converted " f"to jump and mark instructions: {name}"

test/terra/backends/aer_simulator/test_cliffords.py

@@ -16,6 +16,7 @@
 from test.terra.reference import ref_1q_clifford
 from test.terra.reference import ref_2q_clifford
 from qiskit import transpile
+from qiskit import QuantumCircuit
 from test.terra.backends.simulator_test_case import SimulatorTestCase, supported_methods
 
 SUPPORTED_METHODS = [

test/terra/reference/ref_2q_clifford.py

@@ -109,6 +109,14 @@ def cx_gate_circuits_deterministic(final_measure=True):
         circuit.measure(qr, cr)
     circuits.append(circuit)
 
+    # test ctrl_states=0
+    circuit = QuantumCircuit(*regs)
+    circuit.cx(qr[0], qr[1], ctrl_state=0)
+    if final_measure:
+        circuit.barrier(qr)
+        circuit.measure(qr, cr)
+    circuits.append(circuit)
+
     return circuits
 
 
@@ -132,6 +140,8 @@ def cx_gate_counts_deterministic(shots, hex_counts=True):
         targets.append({"0x1": shots})  # {"00": shots}
         # CX10.(X^X), |10> state
         targets.append({"0x2": shots})  # {"00": shots}
+        # test ctrl_states=0
+        targets.append({"0x2": shots})  # {"00": shots}
     else:
         # CX01, |00> state
         targets.append({"00": shots})  # {"00": shots}
@@ -149,6 +159,8 @@ def cx_gate_counts_deterministic(shots, hex_counts=True):
         targets.append({"01": shots})  # {"00": shots}
         # CX10.(X^X), |10> state
         targets.append({"10": shots})  # {"00": shots}
+        # test ctrl_states=0
+        targets.append({"10": shots})  # {"00": shots}
     return targets
 
 
@@ -225,6 +237,16 @@ def cx_gate_circuits_nondeterministic(final_measure=True):
         circuit.barrier(qr)
         circuit.measure(qr, cr)
     circuits.append(circuit)
+
+    # test ctrl_states=0
+    circuit = QuantumCircuit(*regs)
+    circuit.h(qr[0])
+    circuit.cx(qr[0], qr[1], ctrl_state=0)
+    if final_measure:
+        circuit.barrier(qr)
+        circuit.measure(qr, cr)
+    circuits.append(circuit)
+
     return circuits
 
 
@@ -236,11 +258,15 @@ def cx_gate_counts_nondeterministic(shots, hex_counts=True):
         targets.append({"0x0": shots / 2, "0x3": shots / 2})
         # CX10.(I^H), Bell state
         targets.append({"0x0": shots / 2, "0x3": shots / 2})
+        # test ctrl_states=0
+        targets.append({"0x1": shots / 2, "0x2": shots / 2})
     else:
         # CX01.(I^H), Bell state
         targets.append({"00": shots / 2, "11": shots / 2})
         # CX10.(I^H), Bell state
         targets.append({"00": shots / 2, "11": shots / 2})
+        # test ctrl_states=0
+        targets.append({"01": shots / 2, "10": shots / 2})
     return targets