Journal article

Towards understanding two-level-systems in amorphous solids: insights from quantum circuits

Clemens Mueller, Jared H Cole, Juergen Lisenfeld



Amorphous solids show surprisingly universal behaviour at low temperatures. The prevailing wisdom is that this can be explained by the existence of two-state defects within the material. The so-called standard tunneling model has become the established framework to explain these results, yet it still leaves the central question essentially unanswered-what are these two-level defects (TLS)? This question has recently taken on a new urgency with the rise of superconducting circuits in quantum computing, circuit quantum electrodynamics, magnetometry, electrometry and metrology. Superconducting circuits made from aluminium or niobium are fundamentally limited by losses due to TLS within the amor..

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University of Melbourne Researchers


Awarded by Deutsche Forschungsgemeinschaft (DFG)

Awarded by Australian Research Council

Funding Acknowledgements

We thank S Meissner, M Schechter, and A Seiler for useful comments and suggestions on the manuscript, and thank J Burnett for valuable comments on TLS-induced phase noise. The authors would also like to acknowledge many useful conversations with the participants of the `tunneling two-level systems and superconducting qubits' workshop held in Sde Boker, September 2016 as well as the workshop `atomic tunneling systems and fluctuating spins interacting with superconducting qubits' at MPIPKS in Dresden, February 2019. We thank Lukas Grunhaupt (Physikalisches Institut, Karlsruhe Institute of Technology) for providing figures 1(b) and (c). J L acknowledges funding from Deutsche Forschungsgemeinschaft (DFG), project LI2446/1-1. This work was supported by the Swiss National Science Foundation through NCCR QSIT and by the Australian Research Council under the Discovery and Centre of Excellence funding schemes (project numbers DP140100375, CE170100026 and CE110001013).