Add the pytest function for MPS in cuquantum.

tests/test_cuquantum_cutensor_backend.py

@@ -2,6 +2,7 @@ from timeit import default_timer as timer
 
 import config
 import numpy as np
+import cupy as cp
 import pytest
 import qibo
 from qibo.models import QFT
@@ -46,3 +47,40 @@ def test_eval(nqubits: int, dtype="complex128"):
     assert 1e-2 * qibo_time < cutn_time < 1e2 * qibo_time
     assert np.allclose(
         result_sv, result_tn), "Resulting dense vectors do not match"
+
+
+@pytest.mark.gpu
+@pytest.mark.parametrize("nqubits", [2, 5, 10])
+def test_mps(nqubits: int, dtype="complex128"):
+    """Evaluate MPS with cuQuantum.
+
+    Args:
+        nqubits (int): Total number of qubits in the system.
+        dtype (str): The data type for precision, 'complex64' for single,
+            'complex128' for double.
+    """
+    import qibotn.cutn
+
+    # Test qibo
+    qibo.set_backend(backend=config.qibo.backend,
+                     platform=config.qibo.platform)
+
+    qibo_time, (circ_qibo, result_sv) = time(
+        lambda: qibo_qft(nqubits, swaps=True))
+
+    result_sv_cp = cp.asarray(result_sv)
+
+    # Test of MPS
+    gate_algo = {'qr_method': False,
+                 'svd_method': {
+                     'partition': 'UV',
+                     'abs_cutoff': 1e-12,
+                 }}
+
+    cutn_time, result_tn = time(
+        lambda: qibotn.cutn.eval_mps(circ_qibo, gate_algo, dtype).flatten())
+
+    print(
+        f"State vector difference: {abs(result_tn - result_sv_cp).max():0.3e}")
+
+    assert cp.allclose(result_tn, result_sv_cp)