Update shadows.py and test_shadows.py

Author: PeilinZHENG

tensorcircuit/shadows.py

@@ -327,7 +327,7 @@ def entropy_shadow(
         return backend.log(backend.sum(backend.power(evs, alpha))) / (1 - alpha)
 
 
-def Renyi_entropy_2(snapshots: Tensor, sub: Optional[Sequence[int]] = None) -> Tensor:
+def renyi_entropy_2(snapshots: Tensor, sub: Optional[Sequence[int]] = None) -> Tensor:
     r"""To calculate the second order Renyi entropy of a subsystem from snapshot, please refer to Brydges, T. et al. Science 364, 260–263 (2019).
     This function is not jitable.
 

tests/test_shadows.py

@@ -8,7 +8,7 @@
     local_snapshot_states,
     global_shadow_state,
     entropy_shadow,
-    Renyi_entropy_2,
+    renyi_entropy_2,
     expection_ps_shadow,
     global_shadow_state1,
     global_shadow_state2,
@@ -111,7 +111,7 @@ def test_state(backend):
 #
 #     expc = np.median(expection_ps_shadow(snapshots, pauli_strings, ps=ps, k=9))
 #     ent = entropy_shadow(snapshots, pauli_strings, sub, alpha=2)
-#     ent2 = Renyi_entropy_2(snapshots, sub)
+#     ent2 = renyi_entropy_2(snapshots, sub)
 #     print(expc, ent, ent2)
 #
 #     pl_snapshots = np.asarray(snapshots).reshape(ns * repeat, nq)