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arXiv · 1609.07351

Second-order decoherence mechanisms of a transmon qubit probed with thermal microwave states

J. Goetz·F. Deppe·P. Eder·M. Fischer·M. Müting·J. P. Martínez·S. Pogorzalek·F. Wulschner·E. Xie·K. G. Fedorov·A. Marx·R. Gross
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Abstract

Thermal microwave states are omnipresent noise sources in superconducting quantum circuits covering all relevant frequency regimes. We use them as a probe to identify three second-order decoherence mechanisms of a superconducting transmon. First, we quantify the efficiency of a resonator filter in the dispersive Jaynes-Cummings regime and find evidence for parasitic loss channels. Second, we probe second-order noise in the low-frequency regime and demonstrate the expected $T^{3}$ temperature dependence of the qubit dephasing rate. Finally, we show that qubit parameter fluctuations due to two-level states are enhanced under the influence of thermal microwave states. In particular, we experimentally confirm the $T^{2}$-dependence of the fluctuation spectrum expected for noninteracting two-level states.

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J. Goetz, F. Deppe, P. Eder, M. Fischer, M. Müting, J. P. Martínez, S. Pogorzalek, F. Wulschner, E. Xie, K. G. Fedorov, A. Marx, R. Gross. 2016-09-23. Second-order decoherence mechanisms of a transmon qubit probed with thermal microwave states. https://doi.org/10.1088/2058-9565/aa66e7

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