Regensburg 2022 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 32: Focus Session: Topological Devices (joint session TT/KFM)

TT 32.6: Talk

Thursday, September 8, 2022, 17:45–18:00, H10

Quantum non-Hermitian topological sensors — •Florian Koch and Jan Carl Budich — Institute of Theoretical Physics, Technische Universität Dresden

Recent discoveries regarding the exceptional spectral and topological properties of non-Hermitian (NH) tight-binding models, e.g. their striking boundary-sensitivity, have triggered the quest for constructing novel sensors [1,2]. Here, using quantum master equations we promote the architecture of such sensing devices to a fully quantum-mechanical framework. Specifically, we study a setting of weakly-coupled bosonic modes arranged in an array with broken ring geometry that would realize a NH topological phase in the classical limit. Employing methods from quantum-information theory of Gaussian states, we show that a small coupling induced between the ends of the broken ring may be detected with a precision that increases exponentially in the number of coupled modes. Our findings pave the way towards designing quantum NH topological sensors (QUANTOS) that may observe with high precision any physical observable that couples to the boundary conditions of the device [3].

[1] J.C. Budich and E.J. Bergholtz, Phys. Rev. Lett. 125, 180403 (2020).

[2] E.J. Bergholtz, J.C. Budich, and F.K. Kunst, Rev. Mod. Phys. 93, 015005 (2021).

[3] F. Koch and J.C. Budich, Phys. Rev. Res. 4, 013113 (2022).