Put the initialization of states into a function to facilitate testing

src/qibotn/qasm_quimb.py

@@ -173,6 +173,19 @@ def qasm_QFT(nqubits: int, qasm_str: str, with_swaps: bool = True, psi0=None):
     return circ
 
 
+def init_state_tn(nqubits, init_state_sv, tn_lib="quimb"):
+    dims = tuple(2 * np.ones(nqubits, dtype=int))
+
+    if tn_lib == "quimb":
+        init_state_MPS = qtn.tensor_1d.MatrixProductState.from_dense(
+            init_state_sv, dims)
+    else:
+        # TODO: Add cuquantum later
+        assert False, "Unsupported tensor network backend in initilization"
+
+    return init_state_MPS
+
+
 def tn_circ_eval(nqubits, qasm_circ, init_state, swaps=True, tn_lib="quimb",
         backend='numpy'):
     if tn_lib == "quimb":
@@ -207,10 +220,8 @@ def eval_QI_qft(nqubits, backend="numpy", qibo_backend="qibojit", with_swaps=Tru
 
     #####################################################################
     # Quimb circuit
-    # convert vector to MPS
-    dims = tuple(2 * np.ones(nqubits, dtype=int))
-    init_state_MPS = qtn.tensor_1d.MatrixProductState.from_dense(
-        init_state_quimb, dims)
+    init_state_MPS = init_state_tn(nqubits=nqubits,
+                                   init_state_sv=init_state_quimb)
 
     # construct quimb qft circuit
     start = timer()