Segmentation fault with lightning kokkos and 0 qubits.

[erick-xanadu]

With lightning.qubit and default.qubit:

>>> dev = qml.device("lightning.qubit", 0)
>>> qml.qnode(dev)(lambda : qml.state())()
tensor([1.+0.j], requires_grad=True)

With kokkos

>>> dev = qml.device("lightning.kokkos", 0)
Kokkos::OpenMP::initialize WARNING: OMP_PROC_BIND environment variable not set
  In general, for best performance with OpenMP 4.0 or better set OMP_PROC_BIND=spread and OMP_PLACES=threads
  For best performance with OpenMP 3.1 set OMP_PROC_BIND=true
  For unit testing set OMP_PROC_BIND=false

>>> qml.qnode(dev)(lambda : qml.state())()
Segmentation fault (core dumped)

[maliasadi]

Thanks @erick-xanadu! The following patch will fix the issue,

--- a/pennylane_lightning/core/src/simulators/lightning_kokkos/StateVectorKokkos.hpp
+++ b/pennylane_lightning/core/src/simulators/lightning_kokkos/StateVectorKokkos.hpp
@@ -111,10 +111,9 @@ class StateVectorKokkos final
                 Kokkos::initialize(kokkos_args);
             }
         }
-        if (num_qubits > 0) {
-            data_ = std::make_unique<KokkosVector>("data_", exp2(num_qubits));
-            setBasisState(0U);
-        }
+
+        data_ = std::make_unique<KokkosVector>("data_", exp2(num_qubits));
+        setBasisState(0U);
     };