fix MPS sample handling of RNG seed

quimb/tensor/circuit.py

@@ -4043,7 +4043,8 @@ def sample(
         seed : None, int, or generator, optional
             A random seed or generator to use for reproducibility.
         """
-        for config, _ in self._psi.sample(C, seed=seed):
+        rng = np.random.default_rng(seed)
+        for config, _ in self._psi.sample(C, seed=rng):
             yield "".join(map(str, config))
 
     def fidelity_estimate(self):
@@ -4154,9 +4155,10 @@ def sample(self, C, seed=None):
         str
             The next sample bitstring.
         """
+        rng = np.random.default_rng(seed)
         # configuring is in physical order, so need to reorder for sampling
         ordering = self.calc_qubit_ordering()
-        for config, _ in self._psi.sample(C, seed=seed):
+        for config, _ in self._psi.sample(C, seed=rng):
             yield "".join(str(config[i]) for i in ordering)
 
     @property

tests/test_tensor/test_circuit.py

@@ -696,6 +696,13 @@ def test_mps_sampling(self):
         for x in circ.sample(10):
             assert x in {"000010", "111101"}
 
+    def test_mps_sampling_seed(self):
+        N = 1
+        circ = qtn.CircuitMPS(N)
+        circ.h(0)
+        samples = list(circ.sample(100, seed=1234))
+        assert len(set(samples)) == 2
+
     def test_permmps_sampling(self):
         N = 6
         circ = qtn.CircuitPermMPS(N)
@@ -710,6 +717,13 @@ def test_permmps_sampling(self):
         for x in circ.sample(10):
             assert x in {"000010", "111101"}
 
+    def test_permmps_sampling_seed(self):
+        N = 1
+        circ = qtn.CircuitPermMPS(N)
+        circ.h(0)
+        samples = list(circ.sample(100, seed=1234))
+        assert len(set(samples)) == 2
+
 
 class TestCircuitGen:
     @pytest.mark.parametrize(