Protected login

Hi, how could I prove in Nova so that only the user I define can log in to the admin? I don't want anyone else to get into the admin. I try it like this but it doesn't work for me ..

protected function gate()
    {
        Gate::define('viewNova', function ($user) {
            return in_array($user->email, [
                '[email protected]',
            ]);
        });
    }