Berlin 2018 – wissenschaftliches Programm

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PLV: Plenarvorträge

PLV VII

PLV VII: Plenarvortrag

Mittwoch, 14. März 2018, 08:30–09:15, H 0105

Nanoscale thermal imaging of dissipation in quantum systems — •Eli Zeldov — Weizmann Institute of Science, Rehovot, Israel

Imaging energy dissipation in quantum systems by existing thermal imaging methods is currently impossible due to limited sensitivity and low temperature incompatibility. We developed a scanning SQUID-on-tip nanothermometer with sub 50 nm diameter that provides cryogenic thermal imaging with four orders of magnitude improved sensitivity of below 1 μK/Hz1/2 [1]. The non-contact non-invasive thermometry allows thermal imaging of minute energy dissipation down to the fundamental Landauer limit of 40 fW for continuous readout of a single qubit at 1 GHz at 4.2 K. By varying potential between the SQUID-on-tip and the sample a spectroscopic analysis of the dissipation process is attained. Using this scanning nanothermometry we visualize and control phonon emission due to inelastic electron scattering off individual atomic defects in graphene [2], which occurs, however, only when the Fermi level comes into resonance with the quasi-bound states at the defects. The atomic defects are very rare in the bulk but abundant at the edges, acting as switchable atomic-scale phonon emitters that establish the dominant dissipation mechanism in graphene.

[1] D. Halbertal, J. Cuppens, M. Ben Shalom, L. Embon, N. Shadmi, Y. Anahory, H.R. Naren, J. Sarkar, A. Uri, Y. Ronen, Y. Myasoedov, L.S. Levitov, E. Joselevich, A.K. Geim, and E. Zeldov, Nature 539, 407 (2016). [2] D. Halbertal, M. Ben Shalom, A. Uri, K. Bagani, A.Y. Meltzer, I. Marcus, Y. Myasoedov, J. Birkbeck, L.S. Levitov, A.K. Geim, and E. Zeldov, Science 358, 1303 (2017).