Quantum computing promises to be one of the next big things in technology, and that's prompted many growth investors to pile into the industry. But when we think "next big thing," that doesn't necessarily mean tomorrow or even a year or two from now. One thing that's held some investors back from getting in on this high-potential technology is the idea that its usefulness may be many years or even decades away. Even experts haven't always been certain about when this exciting technology might become part of our daily lives. Early last year, Nvidia chief Jensen Huang said quantum computing was decades away from the point of being very useful. A few months later, Huang said otherwise and even announced the creation of a quantum computing research center. And Microsoft (MSFT 0.06%) co-founder Bill Gates said last year that the technology might be ready to solve big problems in three to five years. The reason it's taking a while for quantum computing to become very useful is due to the complexity of the technology. It involves using qubits for calculations rather than the bits used by classical computers -- and qubits are fragile and often difficult to scale up. But there's reason to be optimistic about the progress of certain companies. In fact, two quantum stocks are further along than anyone is giving them credit for. Let's check them out. 1. Microsoft You probably know Microsoft well for its software suite, including popular products like Word and Excel, and you might even be familiar with the company's cloud computing business. These are major engines, driving years of revenue and profit growth -- and this has translated into returns for investors, too, with the stock rising 700% over the past decade. NASDAQ: MSFT Key Data Points But, while Microsoft is a