Impact of charge dispersion on lifetime of transmon with different electrode gaps
ORAL
Abstract
Non-equilibrium quasiparticles tunneling across the Al/AlOx/Al Josephson junction is a source of energy relaxation for transmon qubits. To suppress the quasiparticle tunneling, the superconducting gaps across the junction should be different. We fabricated a 3D transmon qubit where the bottom oxygen doped Al base electrode has the largest superconducting gap, a less doped counter-electrode with a smaller gap, and finally a third pure Al capping electrode. At a base temperature of 20 mK, the T1 for the qubit transition temporally varied from 80 to 150 μs. The charge dispersion of g-f transition from the spectrum is around 1MHz. By adding a time delay to this standard spectroscopy sequence, we measured the lifetime of |f> state as a function of g-f transition frequency as well as the life time of |e> state from the subsequent |e> to |g> decay.
*This work was supported by the Maryland Quantum Materials Center, the Joint Quantum Institute, and the Laboratory for Physical Sciences.
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Presenters
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Kungang Li
- University of Maryland, College Park; Quantum Materials Center, University of Maryland, College Park
- University of Maryland, College Park