I have always been very, very suspicious about finding artificial means – it doesn’t really matter whether it is a mantra or a drug.
Do you know that book by Aldous Huxley about the gates of heaven and hell?
One of his basic points (which I think was a mistake) was that he thought that somehow he had found the key to another realm.
That was the basic notion, and he wrote very beautifully about it.
Now, as more and more people that tried it found out, you don’t get a gateway to heaven.
You get, at the most, a gateway into another chamber within yourself.