A startup of physicists from Caltech has raised 300 million dollars (about 275 million euros) to build a quantum computer - and with a promise that sounds too good to be true: instead of millions, it will need only 20,000 qubits.

The company Oratomic only entered the race this year, aiming to build the first quantum computer with practical, "utility" use by the end of the decade. The huge Series A round was led by ARCH Venture Partners, Spark Capital and Khosla Ventures, and among the investors is Jeff Bezos's fund, as well as Index Ventures and Bain Capital. When names like these line up on a single cheque, that in itself is a message to the market.

Oratomic's technical trick is lasers that act as "optical tweezers" - holding individual atoms in place and using them as the basis of computation. The key discovery, the founders say, is that their approach can correct errors with far fewer qubits than was thought possible. Since quantum computers are extremely sensitive to noise, error correction is precisely the difference between a scientific experiment and a real tool.

"Earlier you couldn't have convinced any of us to found a quantum computing company, because we thought it was too far off", admits CEO Dolev Bluvshtein. Honesty that counts for something - but also a reminder that the whole industry has for years promised a breakthrough that is forever "by the end of the decade". Three hundred million dollars buys a lot of research; whether it buys a working quantum computer, we'll see only when the first one actually solves a problem classical machines cannot.