Regensburg 2016 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 6: Transport: Quantum Coherence and Quantum Information Systems - Experiment
(Joint session of HL, MA and TT organized by TT)
MA 6.5: Vortrag
Montag, 7. März 2016, 10:45–11:00, H22
Thermal microwave states acting on a superconducting qubit — •Jan Goetz1,2, Miriam Müting1,2, Max Haeberlein1,2, Friedrich Wulschner1,2, Edwar Xie1,2,3, Peter Eder1,2,3, Michael Fischer1,2, Frank Deppe1,2, Kirill Fedorov1,2, Hans Hübl1,2, Frank Deppe1,2,3, 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), Schellingstraße 4, 80799 München, Germany
We analyze the influence of broadband thermal states in the microwave regime on the coherence properties of a superconducting (transmon) qubit coupled to a transmission line resonator. We generate the thermal states inside the resonator by heating a 30 dB attenuator to emit blackbody radiation into a transmission line. In the absence of thermal fluctuations, the qubit coherence time is limited by relaxation. We find that the relaxation rate is almost unaffected by the presence of a thermal field inside the resonator. However, such states induce significant dephasing which increases quadratically with the number of thermal photons, whereas for a coherent population of the resonator, the increase shows a linear behavior. These results confirm the different photon statistics, being Poissonian for a coherent population and super-Poissonian for a thermal population of the resonator.
This work is supported by the German Research Foundation through SFB 631 and FE 1564/1-1, EU projects CCQED, PROMISCE, the doctorate program ExQM of the Elite Network of Bavaria.