Fig. 1: Tantalum-based transmon superconducting qubit.
a False-colored optical microscope image of a transmon qubit. The transmon consists of a Josephson junction shunted by two large capacitor islands made of tantalum (blue) on sapphire (gray). b Device layout image and corresponding circuit diagram of the transmon qubit coupled to the resonator via a coupling capacitor. c T1 measurement of Device 18, showing the excited state population Pe as a function of delay time Δt. Line represents a single exponential fit with a characteristic T1 time of 0.36 ± 0.01 ms. d Four-probe resistance measurement of the tantalum film showing Tc = 4.38 ± 0.02 K, consistent with the critical temperature of α-tantalum.
