Decoherence spectroscopy of individual two-level tunneling defects

admin   2017-11-08 16:30:33   3897

报告题目:Decoherence spectroscopy of individual two-level tunneling defects
报告时间:2017-11-10 15:10 (星期五)
报告人:Gerd Schoen(KarlsruheInstitute of Technology, Germany)


Progress with microfabricated quantum devices has revealed that an ubiquitous source of noise are parasitic two-level systems (TLSs). Forsuperconducting qubits, TLSs residing on electrode surfaces and in tunneljunctions account for a major part of decoherence and thus pose a seriousroadblock to the realization of solid-state quantum processors. Recentexperiments [J. Lisenfeldet al., Sci. Rep. 6, 23786 (2016)] utilized asuperconducting qubit to explore the quantum state evolution of thesematerial-based TLSs in order to shed new light on their individual propertiesand environmental interactions. 

We study theoretically the dephasing of these individual high-frequencyTLSs due to their interaction with an ensemble of low-frequency thermal TLSswhich are described by the standard tunneling model (STM). We show that thedephasing by the bath of TLSs explains both the dependence of the Ramseydephasing rate on an externally applied strain as well as its order ofmagnitude, as observed in experiment.


Prof. Gerd Schoen是国际著名学者,是2011年国际低温物理大奖(Fritz London Memorial Prize)获得者。其研究组在介观小系统物理的诸多领域取得了突出成就, 先后培养了大约20名在德国及周边国家大学工作的教授。Schoen教授获得的其它重要奖项包括:1982年 HeisenbergFellowship; 1989年  Walter Schottky Prize of the German PhysicalSociety, shared with U. Eckern and W. Zwerger;   1995 年   A. v. Humboldt Award of theAcademy of Finland ;  2000 年   Heinrich Hertz Prize of theUniversity of Karlsruhe and the Badenwerk Foundation, shared with Jan v. Delftand H. Schoeller ;   2001 年   Miller Visiting ProfessorAward, UC Berkeley. 


TheoreticalSolid State Physics;  Superconductivity, incl. non-equilibriumeffects, NS and FS heterostructures; Electron transport innanostructures, incl. charging effects, quantum transport; Quantum informationdevices, relaxation and decoherence processes. 


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