Dresden 2017 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 38: Transport: Quantum Coherence and Quantum Information Systems - Experiment (jointly with MA, HL)
TT 38.2: Talk
Wednesday, March 22, 2017, 09:45–10:00, HSZ 03
Second-order decoherence mechanisms of a transmon qubit probed with thermal microwave states — •Frank Deppe1,2,3, Jan Goetz1, Peter Eder1,2,3, Michael Fischer1,2,3, Stefan Pogorzalek1,2,3, Edwar Xie1,2,3, Kirill G. Fedorov1,2, Achim Marx1, and Rudolf Gross1,2,3 — 1Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany — 2Physik-Department, TU München, 85748 Garching, Germany — 3Nanosystems Initiative Munich (NIM), 80799 München, Germany
Using thermal microwaves as a probe, we identify three second-order decoherence mechanisms of a superconducting transmon qubit. 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 T3 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 present experimental evidence for a model based on noninteracting two-level states.
The authors acknowledge support from DFG through FE 1564/1-1, the doctorate program ExQM of the Elite Network of Bavaria, and the IMPRS ‘Quantum Science and Technology’.