Artificial intelligence (AI) may be the technology that is most in focus on Wall Street right now, but quantum computing is the next major tech trend on the horizon. Numerous companies are competing to develop versions of it, and the breakthroughs quantum computers are expected to deliver in a host of areas, from drug development to logistics to materials science, could be breathtaking. Although useful quantum computers are still a few years out, I think investors must respond now and position their portfolios accordingly. The biggest gains for some of the eventual leaders will happen early on, and the sooner investors get on board, the better off they will be. In my view, these three companies are among those best positioned to benefit when quantum computing goes mainstream. D-Wave Quantum D-Wave Quantum (QBTS 8.04%) is one of my favorite companies in the sector. While many companies are developing broad-purpose quantum computers, D-Wave is taking a narrower approach. Its primary products use a technology called quantum annealing, which makes them unsuitable for many applications. However, they are ideally suited to handling optimization problems, and those make up a large fraction of the types of tasks that quantum computers will be used for. Moreover, D-Wave already has early iterations of these computing units available, and they are making a real-world impact. Thanks to a recent acquisition, the company is also pursuing gate-model systems that are more akin to what others in the industry are going after, giving it two chances at success. NYSE: QBTS Key Data Points Recently, D-Wave closed a $20 million deal to sell a system to Florida Atlantic University and inked a $10 million agreement with a Fortune 100 company. This showcases early demand for D-Wave's systems, and if these deals are successful, they could lead to future sales