Table 1 Characteristic parameters of the eight-qubit device.

ωr represents the frequency of the resonator, Formula is the qubit frequency (at zero flux), Formula is the frequency of the flux-tunable qubit at Formula, η is the anharmonicity of the qubit, T1 is the energy relaxation time of the qubit, Formula is the Ramsey phase coherence time, ℱRO is the single-shot readout assignment fidelity, and p is the single-qubit gate average error probability estimated as the decay of polarization under randomized benchmarking with Pauli generators of the Clifford group. Note that the anharmonicities of the flux-tunable qubits are measured at their operating frequencies.

Qubit
index
ωr/2π
(MHz)
Formula
(MHz)
Formula
(MHz)
− η/2π
(MHz)
T1
(μs)
Formula
(μs)
RO
(%)
p
(%)
Q05065.03719.1216.234.118.195.01.43
Q15278.04934.03817.9204.017.04.393.20.70
Q25755.04685.8199.414.212.993.71.02
Q35546.04870.93830.0204.015.86.690.00.37
Q45164.04031.5211.023.718.795.2*0.70
Q55457.34817.63920.0175.228.011.787.3*2.00
Q65656.84662.5196.616.915.493.8*1.20
Q75388.14812.43803.5182.85.68.689.9*1.35

*Non-quantum nondemolition readout (49).