Topological Thermal Hall Conductance of Even-Denominator Fractional States

The even-denominator fractional quantum Hall (FQH) states ν = 5/2 and ν = 7/2 have been long predicted to host non-Abelian quasiparticles. Their present energy-carrying neutral modes are hidden from customary conductance measurements and thus motivate thermal transport measurements, which are sensitive to all energy-carrying modes. While past “two-terminal” thermal conductance (𝑘_2⁢𝑡⁢𝑇) measurements already proved the non-Abelian nature of the ν = 5/2 FQH state, they might have been prone to a lack of thermal equilibration among the counterpropagating edge modes. Here, we report a novel thermal Hall conductance measurement of the ν = 5/2 and ν = 7/2 states, being insensitive to equilibration among edge modes. We verify the state’s non-Abelian nature, with both states supporting a single upstream Majorana edge mode (hence, a particle-hole Pfaffian order). While current numerical works predict a different topological order, this contribution should motivate further theoretical work.