Entropy measurement of a double quantum dot

ORAL

Abstract

Double quantum dots (DQD) offer a convenient platform for the realization and measurement of complex, experimentally tunable Hamiltonians. The electronic entropy, S, is an appealing metric to probe such Hamiltonians experimentally, as it is directly related to the degrees of freedom d of the ground state of electrons in the system, S = kblnd. Here we present measurements of S for a system of two capacitively coupled lateral quantum dots (QD), investigating how entropy changes throughout the (0,1)↔(1,0) transition region of the stability diagram, where inter-dot Coulomb effects increase the gap to the (1,1) charge state. Although the measurements are sensitive primarily to the charge of one of the two dots, S reflects the system as a whole, which is strongly modified by coupling between the dots and to a thermal reservoir. Looked at from a different perspective, our measurement can be understood as a demonstration of the use of one QD as entropy sensor for a second quantum system, an important advance for experiments where the thermodynamics of the system of interest may be hard to probe directly.

*This project has received funding from European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme under grant agreement No 951541. Y. Meir acknowledges discussions with A. Georges and support by the Israel Science Foundation (grant 3523/2020). Experiments at UBC were undertaken with support from the Stewart Blusson Quantum Matter Institute, the Natural Sciences and Engineering Research Council of Canada, the Canada Foundation for Innovation, the Canadian Institute for Advanced Research, and the Canada First Research Excellence Fund, Quantum Materials and Future Technologies Program. S.F., G.C.G. and M.M. were supported by the US DOE Office of Basic Energy Sciences, Division of Materials Sciences and Engineering award no. DE-SC0006671, with additional support from Nokia Bell Laboratories for the MBE facility gratefully acknowledged.

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Presenters

  • Owen I Sheekey

    • University of British Columbia

Authors

  • Owen I Sheekey

    • University of British Columbia

  • Tim J Child

    • University of British Columbia

  • Silvia Lüscher

    • University of British Columbia

  • Saeed Fallahi

    • Purdue University

  • Geoffrey C Gardner

    • Purdue University
    • Purdue University, Microsoft Quantum Materials Lab-Purdue, West Lafayette, Indiana 47907, USA)
    • Microsoft Quantum Materials Lab-Purdue

  • Michael J Manfra

    • Department of Physics and Astronomy, Birck Nanotechnology Center, and Microsoft Quantum Lab Purdue, Purdue University
    • Purdue University
    • Purdue University, West Lafayette, Indiana 47907, USA

  • Yaakov Kleeorin

    • Center for the Physics of Evolving Systems, University of Chicago
    • University of Chicago

  • Yigal Meir

    • Ben-Gurion University of the Negev

  • Joshua Folk

    • University of British Columbia