Quantum computing may soon take off. Are the pure plays ready to go the distance?IBM aims to launch a fault-tolerant quantum supercomputer by 2029. Above, parts of the IBM Quantum System Two. (Angela Weiss / AFP via Getty Images)Quantum computing has graduated from a theoretical curiosity to a stock market phenomenon. The sector’s shares routinely post some of the biggest moves in the market, up and down, as investors place their bets on the future of computing.