Fig. 1: Qubit design and coherence data.
From: Mitigation of interfacial dielectric loss in aluminum-on-silicon superconducting qubits
a False-colored micrograph of a qubit device. A portion of the input/output transmission line is shown in blue, coupled to a readout resonator, shown in purple. The qubit capacitor is shown in green. The inset shows a scanning electron micrograph (SEM) of the Josephson junction. b Time-averaged qubit quality factor Q as a function of the measured qubit relaxation time relative to the calculated Purcell decay time, T1/Tp, for qubits fabricated on wiring layers of 150, 300, and 500 nm. The quality factor of those qubits with T1 ≪ Tp is closer to the limit set by the TLS loss. Qubits displayed by the same marker are made on one wafer. c A histogram showing the relaxation time of the best qubit with average T1 = 270 μs plus/minus one standard deviation of 83 μs. d 160 T1 measurements of the qubit in (c) over a span of 48 h. Fit error bars are smaller than markers where not visible. e Demonstration of the exponential fit to the longest T1 measured.
