Way back in 2016, we published an article titled Applying Moore’s Law to Quantum Qubits. At that time IBM had recently introduced their 5 qubit Quantum Experience and D-Wave had their D-Wave 2X with 1048 qubits. We recently reviewed the chart and saw that although the 2016 prediction wasn’t bad, it was a little overoptimistic. So we decided to provide an updated version of the chart based upon what did happen over the past three years, our estimation of some of the near term roadmaps and extrapolations into the future.

The format of the chart remains the same. The horizontal double lines represent our estimation of the number of logical qubits that would be required to implement certain applications in a gate level machine. The blue slanted line provides an estimate of the number of qubits that we may see in a adiabatic quantum annealing computer and the orange slanted lines provide an estimate of the number of physical qubits for various gate level implementations. We continue to estimate that qubit counts will double every 1-2 years.

Although the chart doesn’t directly provide a forecast for qubit quality improvements, the impact of qubit quality can be seen in the additional three slanted dashed lines labelled Logical (10:1), Logical (100:1), Logical (1000:1). The ratios denote a Physical:Logical qubit ratio. As qubit quality improves, the number of physical qubits required to implement an error corrected logical qubit will decrease. When this happens the computational capacity will be higher for a given number of physical qubits.

There is a possibility that one or more organizations will have a breakthrough and make this chart completely obsolete. We are aware of organizations that have much more aggressive goals that what is shown. However, we will note that increasing the numbers of qubits while simultaneously working to increase the qubit quality is quite difficult. Problems such as crosstalk, control signal fidelity, wiring and various mechanical issues all work to make improving qubit counts and qubit quality conflicting goals. We are also aware that over the past three years, several quantum hardware projects have resulted in slipped schedules and were introduced later than the teams initially expected. Quantum technology is hard and small details can be missed which will require another prototype round and delay the schedules.

January 24, 2020