Berlin 2024 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 3: Topology: Quantum Hall Systems

TT 3.5: Invited Talk

Monday, March 18, 2024, 10:30–11:00, H 2053

Topological Thermal Hall Conductance of Even Denominator Fractional States — •Moty Heiblum — Weizmann Institute of Science Rehovot 76100, Israel

The even denominator fractional quantum Hall (FQH) states ν=5/2 and ν=7/2, have been long predicted to host non-abelian quasiparticles. The presence of energy-carrying neutral modes cripples customary conductance measurements and thus motivates thermal transport measurements, which already proved to be sensitive to all energy-carrying modes. Each state has a different capacity to carry quanta of heat - as expressed by the so-called: ’central charge’ - identifying the state’s topological order. While the ’two-terminal’ thermal conductance measurements identified the topological orders of abelian and non-abelian QH states, they are prone to partial thermal equilibration among counter-propagating modes. Here, we report a ’four-terminal’ thermal Hall conductance measurement, which separately measures the heat carried by the downstream and upstream chiral modes. This measurement is insensitive to thermal equilibration among modes. We verify that the ν=5/2 and ν=7/2 states are non-abelian, supporting a single upstream Majorana mode, thus obeying the Particle-Hole Pfaffian topological order. While current numerical works predict a different central charge, this contribution should motivate further theoretical work.

Keywords: non-abelian quasiparticles; fractional quantum Hall; thermal conductance; Majorana modes; Particle-Hole Pfaffian topology