tests

tests/test_quantum_info_superoperator_transformations.py

@@ -3,6 +3,7 @@
 
 from qibo import matrices
 from qibo.config import PRECISION_TOL
+from qibo.quantum_info.linalg_operations import partial_trace
 from qibo.quantum_info.random_ensembles import random_density_matrix, random_statevector
 from qibo.quantum_info.superoperator_transformations import (
     chi_to_choi,
@@ -40,6 +41,7 @@
     to_choi,
     to_liouville,
     to_pauli_liouville,
+    to_stinespring,
     unvectorization,
     vectorization,
 )
@@ -363,6 +365,25 @@ def test_to_chi(backend, normalize, order, pauli_order):
     backend.assert_allclose(chi, test_chi, atol=PRECISION_TOL)
 
 
+@pytest.mark.parametrize("test_a0", [test_a0])
+def test_to_stinespring(backend, test_a0):
+    test_a0_ = backend.cast(test_a0)
+    state = random_density_matrix(2**1, seed=8, backend=backend)
+
+    target = test_a0_ @ state @ backend.np.conj(test_a0_.T)
+
+    environment = (1, 2)
+
+    global_state = backend.identity_density_matrix(len(environment), normalize=True)
+    global_state = backend.np.kron(state, global_state)
+
+    stinespring = to_stinespring(test_a0_, (0,), len(environment) + 1, backend=backend)
+    stinespring = stinespring @ global_state @ backend.np.conj(stinespring.T)
+    stinespring = partial_trace(stinespring, traced_qubits=environment, backend=backend)
+
+    backend.assert_allclose(stinespring, target, atol=PRECISION_TOL)
+
+
 @pytest.mark.parametrize("test_superop", [test_superop])
 @pytest.mark.parametrize("order", ["row", "column"])
 def test_choi_to_liouville(backend, order, test_superop):