Problem when installing "lightning.gpu"

Hi @Bach_Bao, welcome to the Forum!

I think you might be missing custatevec, which is an NVIDIA library, and the CUDA version is too high.
I would recommend creating a new virtual environment and running the following:

python -m pip install pennylane custatevec-cu11 pennylane-lightning-gpu

Also, note that lightning.gpu requires a CUDA compute capability of SM7.0 or newer (Volta era and newer), so make sure that your GPU is compatible. You can find more details in the answer by mlxd here.

Let me know if this solves your issue!