Decoherence characterization of three-dimensional transmon

Abstract

The decoherence time of superconducting qubit is one of the main parameters that determine whether superconducting quantum computation can be realized. This paper mainly focuses on three-dimensional (3D) transmon. The sample is fabricated on SiO substrate, and measured in 10 mK temperature. By measuring Rabi oscillation, energy relaxation, Ramsey oscillation and spin echo, the decoherence time constants of 3D transmon are characterized. The results show that the decoherence time is around several hundred nanoseconds. Based on the relationship of different decoherence time constant, we have the concludes that the possible reason to diminish the decoherence time is the defect in SiO substrate, but not the low frequency noises.