improve fss function and fix token multiprocessing issue

Author: refraction-ray

examples/mipt_pideal.py

@@ -12,6 +12,7 @@
 K = tc.set_backend("jax")
 tc.set_dtype("complex128")
 # tf backend is slow (at least on cpu)
+tc.set_contractor("cotengra-16-64")
 
 
 def delete2(pick, plist):

tensorcircuit/applications/physics/fss.py

@@ -18,21 +18,24 @@ def data_collapse(
     xL: List[List[float]] = []  # x=(p-pc)L^(1/\nv)
     yL: List[List[float]] = []  # y=S(p,L)-S(pc,L) or S(p,L)
     pc_list = []
+    if not isinstance(p[0], list):
+        p = [p for _ in n]  # type: ignore
     for n0 in range(len(n)):
         xL.append([])
         yL.append([])
-        for p0 in range(len(p)):
-            xL[n0].append((p[p0] - pc) * (n[n0] ** (1 / nu)))
-            pc_L = pc_linear_interpolation(p, obs[n0], pc)
+        for p0 in range(len(p[n0])):  # type: ignore
+            xL[n0].append((p[n0][p0] - pc) * (n[n0] ** (1 / nu)))  # type: ignore
+            pc_L = pc_linear_interpolation(p[n0], obs[n0], pc)  # type: ignore
             if obs_type == 0:
-                yL[n0].append((obs[n0][p0] - pc_L) * n[n0] ** (beta / nu))
+                yL[n0].append((obs[n0][p0] - pc_L) * n[n0] ** beta)
                 # entanglement with only collapse and no crossing
             else:
-                yL[n0].append(obs[n0][p0] * n[n0] ** (beta / nu))
+                yL[n0].append(obs[n0][p0] * n[n0] ** beta)
                 # tripartite mutual information
         pc_list.append(pc_L)
-
-    xL_all = np.reshape(xL, -1)
+    xL_all = []
+    for i in range(len(xL)):
+        xL_all.extend(xL[i])
     yL_ave = []
     loss = []
     for x0 in range(len(xL_all)):
@@ -48,7 +51,7 @@ def data_collapse(
         yL_ave.append(ybar)
     loss = np.sum(loss)
 
-    return pc_list, xL, np.array(yL), loss  # type: ignore
+    return pc_list, xL, yL, loss  # type: ignore
 
 
 def pc_linear_interpolation(p: List[float], SA: List[float], pc_input: float) -> float:

tensorcircuit/cloud/apis.py

@@ -237,9 +237,9 @@ def set_token(
     if cached:
         # file_token = backend.tree_map(b64encode_s, saved_token)
         file_token = {k: b64encode_s(v) for k, v in saved_token.items()}
-
-        with open(authpath, "w") as f:
-            json.dump(file_token, f)
+        if file_token:
+            with open(authpath, "w") as f:
+                json.dump(file_token, f)
 
     return saved_token
 

tensorcircuit/experimental.py

@@ -347,6 +347,7 @@ def grad_f(*args: Any, **kws: Any) -> Any:
 
 
 # TODO(@refraction-ray): add SPSA gradient wrapper similar to parameter shift
+# -- using noisyopt package instead
 
 
 def finite_difference_differentiator(

tensorcircuit/mpscircuit.py

@@ -52,8 +52,9 @@ def split_tensor(
             return backend.qr(tensor)  # type: ignore
 
 
-# TODO(@refraction-ray): AD + MPS can lead to numerical stability issue
+# AD + MPS can lead to numerical stability issue
 # E ./tensorflow/core/kernels/linalg/svd_op_impl.h:110] Eigen::BDCSVD failed with error code 3
+# this is now solved by setting os.environ["TC_BACKENDS_TENSORFLOW_BACKEND__SVD_TF_EPS"]="10"
 
 
 class MPSCircuit(AbstractCircuit):