A large-scale universal quantum processor capable of outperforming today’s computers for a wide-range of useful applications needs to have millions of qubits and very few errors.

Small-scale quantum computers called noisy intermediate-scale quantum (NISQ) processors already exist and can be accessed through the internet – i.e., through “cloud quantum computing.” These devices are currently relatively small in qubit number and error prone but are very important in pointing the way forward. To achieve commercial success, we require larger-scale quantum computers with error correction, and that is likely to take at least another 5 years and will continue to improve over the next decade.