From November 2017 to March 2018 there was the announcement of IBM 50 qubit prototype, Intel’s 49 qubit test chip and Google 72 qubit processor. These processors had 10% to as low as 1% error rates. In 2017, D-Wave systems had commercial availability of its 2000 qubit quantum annealing system.
Each of these companies will be doubling the number of qubits every 7 to 16 months. They will also be working to reduce the error rates to 1 in 1000 or 1 in ten thousand.
The peak of this age of noisy quantum computers could be quantum computers with 1000 qubits and two qubit errors rates less than 1 in 1000. This is Google’s near-term goal, which might be reached in 2020.
There could be utility in pushing to 10,000 qubits with two-qubit error rates less than 1 in 10000. This could arrive around 2022.
Rough Timeline of noisy quantum computers
100-150 qubit quantum computers in second half of 2018
200-300 qubit computers in first half of 2019
400-600 qubit computers late in 2019
800-1600 qubit computers in 2020
1600-4000 qubit computers in 2021
3000-10000 qubit computers in 2022
D-Wave could get funding to convert their 5000 qubit quantum annealing system to low error rate qubits. They would try to get this working in 2020-2021 if the funding is provided.
The noisy quantum computers might be better than classical computers for quantum simulation, quantum chemistry or machine learning.
In 2025-2030, there will be the fully error-corrected quantum computers with 100,000 to millions of overall qubits but only 1 in 1000 will be used for calculations. The rest will be needed for error-correction.
Error rates and usefulness of quantum computers
In January 2018, Intel revealed a 49 qubit test chip.
In March 2018, Google Quantum AI Lab announced a 72 qubit processor called Bristlecone.
Rigetti Computing indicated that they would have a 128 qubit processor working and available by August 2019.