generators for for loops in qeb.py

src/qibochem/ansatz/qeb.py

@@ -24,45 +24,20 @@ def qeb_circuit(n_qubits, excitation, theta=0.0, trotter_steps=1) -> Circuit:
     assert n_orbitals % 2 == 0, f"{excitation} must have an even number of items"
 
     n_tuples = len(excitation) // 2
-    i_array = excitation[0:n_tuples]
+    i_array = excitation[:n_tuples]
     a_array = excitation[n_tuples:]
-
-    ry_angle = 2.0 * theta
-
-    mcry_controls = excitation[0:-1]
-
-    fwd_gates = []
-
-    for _i in reversed(i_array[0:-1]):
-        fwd_gates.append(gates.CNOT(i_array[-1], _i))
-
-    for _a in reversed(a_array[0:-1]):
-        fwd_gates.append(gates.CNOT(a_array[-1], _a))
-
+    fwd_gates = [gates.CNOT(i_array[-1], _i) for _i in i_array[-2::-1]]
+    fwd_gates += [gates.CNOT(a_array[-1], _a) for _a in a_array[-2::-1]]
     fwd_gates.append(gates.CNOT(a_array[-1], i_array[-1]))
-
+    fwd_gates += [gates.X(_ia) for _ia in excitation if _ia not in (i_array[-1], a_array[-1])]
+    circuit = Circuit(n_qubits)
+    circuit.add(gate for gate in fwd_gates)
     # MCRY
     # multi-controlled RY gate,
     # negative controls i, a
     # positive control on i_n
-    for _ia in excitation:
-        if _ia not in [i_array[-1], a_array[-1]]:
-            fwd_gates.append(gates.X(_ia))
-
-    mcry_gate = []
-    mcry_gate.append(gates.RY(a_array[-1], ry_angle).controlled_by(*mcry_controls))
-
-    gate_list = []
-
-    for _g in fwd_gates:
-        gate_list.append(_g)
-    for _g in mcry_gate:
-        gate_list.append(_g)
-    for _g in reversed(fwd_gates):
-        gate_list.append(_g)
-
-    circuit = Circuit(n_qubits)
-    for _g in gate_list:
-        circuit.add(_g)
-
+    mcry_controls = excitation[:-1]
+    ry_angle = 2.0 * theta
+    circuit.add(gates.RY(a_array[-1], ry_angle).controlled_by(*mcry_controls))
+    circuit.add(gate for gate in fwd_gates[::-1])
     return circuit