Should you add it to your own portfolio?Quantum computing could be the next major technological breakthrough. While many tech giants are developing quantum systems, there are also a few pure-play quantum computing companies -- and one has been getting significant attention recently.That would be Rigetti Computing (RGTI 8.55%), which develops superconducting quantum computers. Rigetti's up 61% year-to-date as of Dec. 24, and recent SEC filings show that it has been a popular investment. Asset managers have b ...