Fix random number generator seed argument for quantum_volume (#14586) (#14591)

* Fix random number generator seed argument for quantum_volume

The `seed` argument to `quantum_volume` being a `numpy.random.Generator`
resulted in `integers` being called with 0 for the `low` argument. When
called with only a `low` argument like this, this value is taken as one
more than the maximum and 0 is treated as the minimum. This resulted in a
`TypeError` because the range is from 0 to -1. Here the handling of
`Generator` was updated to match how the deprecated `QuantumVolume`
class handled `seed` (which was slightly odd -- it caps the range at the
int64 limit even though the argument is a `u64` in the Rust function --
but probably fine; keeping the range helps keep the behavior consistent
between `QuantumVolume` and `quantum_volume` for a generator with the
same seed).

* Address pylint's misunderstanding of the test import

(cherry picked from commit ba74b5c)

Co-authored-by: Will Shanks <[email protected]>

Author: mergify[bot]

qiskit/circuit/library/quantum_volume.py

@@ -174,6 +174,7 @@ def quantum_volume(
     `arXiv:1811.12926 <https://arxiv.org/abs/1811.12926>`__
     """
     if isinstance(seed, np.random.Generator):
-        seed = seed.integers(0, dtype=np.uint64)
+        max_value = np.iinfo(np.int64).max
+        seed = seed.integers(max_value, dtype=np.int64)
     depth = depth or num_qubits
     return QuantumCircuit._from_circuit_data(qv_rs(num_qubits, depth, seed))

releasenotes/notes/qv-rng-4bc9572d2df93671.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    :func:`qiskit.circuit.library.quantum_volume` was updated to handle a
+    :class:`numpy.random.Generator` as input for its ``seed`` argument.
+    Previously, such a generator argument would result in a ``TypeError``.

test/python/circuit/library/test_quantum_volume.py

@@ -15,6 +15,9 @@
 import unittest
 
 from test.utils.base import QiskitTestCase
+
+import numpy as np
+
 from qiskit.circuit.library import QuantumVolume
 from qiskit.circuit.library.quantum_volume import quantum_volume
 
@@ -50,6 +53,12 @@ def test_qv_function_seed_reproducibility(self):
         right = quantum_volume(10, 10, seed=4196)
         self.assertEqual(left, right)
 
+        rng = np.random.default_rng(256)
+        left = quantum_volume(10, 10, seed=rng)
+        rng = np.random.default_rng(256)
+        right = quantum_volume(10, 10, seed=rng)
+        self.assertEqual(left, right)
+
 
 if __name__ == "__main__":
     unittest.main()