Probing interacting two-level systems with rare-earth ions

Dapeng Ding; David van Driel; Lino M. C. Pereira; Jared F. Bauters; Martijn J. R. Heck; Gesa Welker; Michiel J. A. de Dood; André Vantomme; John E. Bowers; Wolfgang Löffler; Dirk Bouwmeester

doi:10.1103/physrevb.101.014209

arXiv · 1811.05248

Probing interacting two-level systems with rare-earth ions

Dapeng Ding·David van Driel·Lino M. C. Pereira·Jared F. Bauters·Martijn J. R. Heck·Gesa Welker·Michiel J. A. de Dood·André Vantomme·John E. Bowers·Wolfgang Löffler·Dirk Bouwmeester

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Abstract

Two-level systems (TLS) in amorphous materials limit coherence times of a number of solid-state quantum devices. Interactions between TLS become prominent below 100 mK, but the coupling mechanism and statistical properties are still unclear. Here we determine the homogeneous linewidth of ytterbium ions (Yb$ ^{3+} $) in silica glass at 10-80 mK by using photon echo techniques as a probe of TLS. First, the homogeneous linewidth can be reduced by applying a magnetic field of 0.3 T. This effect is due to reduced magnetic interactions between adjacent Yb$ ^{3+} $. Secondly, we observe saturation of the linewidth below 50 mK to a level of approximately 30 kHz, which is much larger than the lifetime-limited value of 0.2 kHz. This saturation behavior is in conflict with the coupling to independent TLS. We show that this effect can be explained by coherently coupled TLS.

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Dapeng Ding, David van Driel, Lino M. C. Pereira, Jared F. Bauters, Martijn J. R. Heck, Gesa Welker, Michiel J. A. de Dood, André Vantomme, John E. Bowers, Wolfgang Löffler, Dirk Bouwmeester. 2020-01-29. Probing interacting two-level systems with rare-earth ions. https://doi.org/10.1103/physrevb.101.014209

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