diff --git a/src/qibotn/mps_contraction_helper.py b/src/qibotn/mps_contraction_helper.py
index fbf0285..ccdc0fa 100644
--- a/src/qibotn/mps_contraction_helper.py
+++ b/src/qibotn/mps_contraction_helper.py
@@ -7,7 +7,7 @@ class MPSContractionHelper:
     """A helper class to compute various quantities for a given MPS.
 
     Interleaved format is used to construct the input args for `cuquantum.contract`.
-    
+
     Reference: https://github.com/NVIDIA/cuQuantum/blob/main/python/samples/cutensornet/tn_algorithms/mps_algorithms.ipynb
 
     The following compute quantities are supported:
diff --git a/src/qibotn/mps_utils.py b/src/qibotn/mps_utils.py
index 62c3f93..f37f1df 100644
--- a/src/qibotn/mps_utils.py
+++ b/src/qibotn/mps_utils.py
@@ -3,9 +3,8 @@ from cuquantum import contract
 from cuquantum.cutensornet.experimental import contract_decompose
 
 
-
 def initial(num_qubits, dtype):
-    """Generate the MPS with an initial state of :math:`\ket{00...00}`"""
+    r"""Generate the MPS with an initial state of :math:`\ket{00...00}`"""
     state_tensor = cp.asarray([1, 0], dtype=dtype).reshape(1, 2, 1)
     mps_tensors = [state_tensor] * num_qubits
     return mps_tensors
@@ -26,9 +25,9 @@ def mps_site_right_swap(mps_tensors, i, **kwargs):
 
 def apply_gate(mps_tensors, gate, qubits, **kwargs):
     """Apply the gate operand to the MPS tensors in-place.
-    
+
     # Reference: https://github.com/NVIDIA/cuQuantum/blob/main/python/samples/cutensornet/tn_algorithms/mps_algorithms.ipynb
-    
+
     Args:
         mps_tensors: A list of rank-3 ndarray-like tensor objects.
             The indices of the ith tensor are expected to be the bonding index to the i-1 tensor,