At the recent Q2B conference it was emphasized that qubit quality is a very important factor in creating a viable quantum computer. So kudos to IBM and Rigetti for documenting the specifications of their respective 20 qubit and 19 qubit chips. However, they are using different formats making it difficult to compare so we decided to put them into a common format. These parameters are shown below in the three tables below. Table 1 shows the qubit count, qubit connectivity, T1 and T2 or T2* times. Table 2 shows the single qubit gate fidelity, the two qubit gate fidelity and the readout fidelities. And Table 3 shows the sources of the data for the first two tables. Note that all of this data is for physical qubits without any error correction.
Although we don’t have complete data for Google’s implementations, they recently provided some information at the Adiabatic Quantum Computing Conference (AQC 2018) where they compared metrics from their 5 and 9 qubit test chips with IBM’s 20 qubit implementation. In the presentation Google indicated that their T1 times are roughly 2-4X worse than IBM’s, but that their single and two qubit gate fidelities are 2-10X better, and their measurement fidelities are roughly 10X better. They also gave their opinion that gate fidelities are a more realistic measure than coherence times and that they expect their forthcoming 49 qubit chip will show similar results as their 5 and 9 qubit chips. You can view Google’s complete presentation at AQC 2018 here.
We encourage anyone else who has data on other implementations to contact us at email@example.com so we can include your data into these tables. Please see the notes at the end of this page that provides additional details of how these tables were generated.
|Qubit Connectivity||T1 (µsec)||T2/T2* (µsec)|
|1-Qubit Gate Fidelity||2-Qubit Gate Fidelity||Read Out Fidelity|