Table 2.

Results of coherence characterization and randomized-benchmarking (RB) experiments for the five unimon qubits

	Φdiff = Φ0/2
Qubit	T1	$T_2^{*}$	$T_2^{\mathrm{e}}$	$A_{{\mathrm{\Phi }}_{\mathrm{diff}}}$	RB fidelity	Gate duration
	(μs)	(μs)	(μs)	(μΦ0)	(%)	(ns)
A	7.2	1.9	6.8	6.1	99.81	13.3
B	8.6	3.1	9.2	15.0	99.90	13.3
C	5.8	2.3	9.3	11.2	99.54	40
D	3.9	2.3	7.0	11.1	99.63	20
E	5.6	2.5	11.4	14.3	99.86	13.3

The measured energy relaxation time T₁, the measured Ramsey coherence time $T_2^{*}$, the measured echo coherence time $T_2^{\mathrm{e}}$, the flux noise density parameter $A_{{\mathrm{\Phi }}_{\mathrm{diff}}}$ at 1 Hz estimated from the echo coherence time, the average fidelity per microwave gate from standard RB experiments, and the gate duration used in the RB experiments. All of the values are measured in the immediate vicinity of the sweet spot Φ_diff = Φ₀/2.