Quantum computers can solve useful problems only if there is less than 1 error every 100 operations, which means 99% operation fidelity.

For the first time in silicon, a team of engineers led by Andrea Morello at UNSW Sydney has demonstrated a three-qubit quantum processor in silicon where every operation – one-qubit logic, two-qubit logic, and qubit initialisation and measurement – is performed with better than 99% fidelity.

This performance was certified using a new, rigorous method developed by collaborators at Sandia National Laboratories. The processor is manufactured with the same methods used for standard silicon computer chips. Its demonstrated performance now makes it suitable for scaling up to practical applications.

Quantum operations with better than 99% fidelity were also demonstrated in two similar experiments at TU Delft and RIKEN, signalling the global maturity of quantum information processing in silicon.

https://newsroom.unsw.edu.au/news/science-tech/quantum-computing-silicon-hits-99-cent-accuracy.