After decades of hype and headlines, quantum computers are finally poised to demonstrate their superiority over conventional machines.

Precisely when this will happen is a bit fuzzy, though. What’s more, it will be a while yet before these magical machines will have any noticeable impact on our lives.

The point at which a quantum machine should be able to perform computations too complex to model on any conventional machine, a landmark known as “quantum supremacy,” is believed to be about 49 qubits, the quantum equivalent of the bits that represent 1 or 0 in a conventional computer.

Google’s researchers appear to be leading in the race for a 49-qubit machine (see “Google’s New Chip Is a Stepping Stone to Quantum Computing Supremacy”). Earlier this week, however, researchers at IBM’s quantum research lab in Yorktown Heights, New York, demonstrated that it is possible to model the behavior of a quantum computer beyond the 49-qubit landmark by harnessing several clever mathematical techniques. IBM is also allowing programmers to experiment with its quantum computers through a cloud platform called IBM Q.

Two IBM quantum computing scientists, Hanhee Paik (left) and Sarah Sheldon, examine one of the company’s machines. IBM

“We don’t think there will be a single landmark or metric to gauge the capability of a quantum computer,” says Bob Wisnieff, a researcher at IBM who’s involved with the new simulation work. “We are actively looking at methods that show quantum machines have an advantage over classical systems.

A quantum computer will need significantly more than 49 qubits in order to be useful. The best measure will be tackling real problems, and it remains unclear when that will become possible, though momentum is building.