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Controlled dephasing of electrons by non-gaussian shot noise

Nature Physics volume 3, pages 534–537 (2007)Cite this article

Abstract

In a ‘controlled dephasing’ experiment1,2,3, an interferometer loses its coherence owing to entanglement of the interfering electron with a controlled quantum system, which effectively is equivalent to path detection. In previous experiments, only partial dephasing was achieved owing to weak interactions between many detector electrons and the interfering electron, leading to a gaussian-phase randomizing process4,5,6,7,8,9,10,11. Here, we report the opposite extreme, where interference is completely destroyed by a few (that is, one to three) detector electrons, each of which has a strong randomizing effect on the phase. We observe quenching of the interference pattern in a periodic, lobe-type fashion as the detector current is varied, and with a peculiar V-shaped dependence on the detector’s partitioning. We ascribe these features to the non-gaussian nature of the noise, which is also important for qubit decoherence12. In other words, the interference seems to be highly sensitive to the full counting statistics of the detector’s shot noise13,14,15,16.

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Figure 1: Schematic diagram of the Mach–Zehnder interferometer and the detector.
Figure 2: The effect of the inner edge channel on Aharonov–Bohm oscillations in the outer edge channel.
Figure 3: The effect of partitioning the detector channel (by QPC0) on the visibility of the interfering signal, at three different detector bias values.
Figure 4: The evolution of the interference pattern as a function of detector voltage, Vdet, for a partitioned detector channel.

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Acknowledgements

We are indebted to Y. Levinson for helpful discussions. The work was partly supported by the Israeli Science Foundation (ISF), the Minerva foundation, the German Israeli Foundation (GIF), the SFB 631 of the DFG, the Nanosystems Initiative Munich (NIM) and the German Israeli Project cooperation (DIP).

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Authors and Affiliations

  1. Department of Condensed Matter Physics, Braun Center for Submicron Research, Weizmann Institute of Science, Rehovot 76100, Israel

    Izhar Neder, Moty Heiblum, Diana Mahalu & Vladimir Umansky

  2. Physics Department, Arnold Sommerfeld Center for Theoretical Physics, and Center for NanoScience, Ludwig-Maximilians-Universität München, 80333 München, Germany

    Florian Marquardt

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  1. Izhar Neder
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  2. Florian Marquardt
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Correspondence to Izhar Neder.

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Neder, I., Marquardt, F., Heiblum, M. et al. Controlled dephasing of electrons by non-gaussian shot noise. Nature Phys 3, 534–537 (2007). https://doi.org/10.1038/nphys627

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