SEMINAR: Non-local thermoelectric detection of interaction and topological properties

In the scope of Nano Colloquia initiative, CNR organized a seminar titled “Non-local thermoelectric detection of interaction and topological properties“. Researcher Alessandro Braggio presented the new studies published in the framework of projects: SPECTRUM, NEThEQS, SUPERGATE, The mechanics in quantum mechanics (GA No. IEC R2 192166), QTHERMONANO.

Interacting systems out-of-equilibrium are difficult problems in mesoscopic physics especially in quantum Hall systems where the electronic coherent nature and interactions make the physics very complex[1,2]. Hereafter, we propose the nonlocal thermoelectric response as a direct detector of the interactions, nonthermal states and the effect of correlations[3]. This is done by assuming a quantum Hall setup where two channels initially kept at different temperatures co-propagate for a finite distance. A thermoelectrical response is only expected when the electron-electron interaction mediates heat exchange between the channels and directly measures the interaction strength. For zero-range interactions, we compute the charge and energy currents and noises of a non-equilibrium integrable interacting system, determining the universal interaction-dependent length scale of the energy equilibration in a Luttinger liquid. Furthermore, using two controllable quantum point contacts we are able to monitor the interacting system thermalisation as well as the fundamental role of cross-correlations measuring, at the same time, the heat exchange at intermediate length scales. The proposed methodology could inspire novel methods in solid-state systems to measure heat currents by direct thermoelectrical conversion of the heat-exchange in electrical current signal.

[1] C. Altimiras, H. le Sueur, U. Gennser, A. Cavanna, D. Mailly, and F. Pierre. Nat. Phys. 6, 34 (2010).
[2] K. Itoh, R. Nakazawa, T. Ota, M. Hashisaka, K. Muraki, and T. Fujisawa. Phys. Rev. Lett. 120, 197701 (2018).
[3] A. Braggio, M. Carrega, B. Sothmann, and R. Sánchez. Phys. Rev. Research 6, L012049 (2024).