arXiv subjects

Ken K. W. Ma

Publications and source records attributed to Ken K. W. Ma.

21 records · Page 2Linked to original sources

arXiv2019

Identification of topological order in the fractional quantum Hall state at $ν=1/4$

The nature of the fractional quantum Hall state at quarter filling in a wide quantum well is still under debate. Both one-component non-Abelian and two-component Abelian orders have been proposed to describe the system. Interestingly, these candidates received support from different experiments under disparate conditions. In this article, we focus on non-Abelian orders from Cooper pairing between composite fermions and the Abelian Halperin-(5,5,3) order. We discuss and predict systematically different experimental signatures to identify them in future experiment. In particular, we address the Mach-Zehnder interferometry experiment and show that it can identify the recently proposed 22111 parton order.

cond-mat.str-el↗

arXiv2019

The sixteenfold way and the quantum Hall effect at half-integer filling factors

Fractional quantum Hall states at half-integer filling factors have been observed in many systems beyond the $5/2$ and $7/2$ plateaus in GaAs quantum wells. This includes bilayer states in GaAs, several half-integer plateaus in ZnO-based heterostructures, and quantum Hall liquids in graphene. In all cases, Cooper pairing of composite fermions is believed to explain the plateaus. The nature of Cooper pairing and the topological order on those plateaus are hotly debated. Different orders are believed to be present in different systems. This makes it important to understand experimental signatures of all proposed orders. We review the expected experimental signatures for all possible composite-fermion states at half-integer filling. We address Mach-Zehnder interferometry, thermal transport, tunneling experiments, and Fabry-Pérot interferometry. For this end, we introduce a uniform description of the topological orders of Kitaev's sixteenfold way in terms of their wave-functions, effective Hamiltonians, and edge theories.

cond-mat.mes-hall↗

arXiv2019

Partial equilibration of integer and fractional edge channels in the thermal quantum Hall effect

Since the charged mode is much faster than the neutral modes on quantum Hall edges at large filling factors, the edge may remain out of equilibrium in thermal conductance experiments. This sheds light on the observed imperfect quantization of the thermal Hall conductance at $ν=8/3$ and can increase the observed thermal conductance by two quanta at $ν=8/5$. Under certain unlikely but not impossible assumptions, this might also reconcile the observed thermal conductance at $ν=5/2$ with not only the PH-Pfaffian order but also the anti-Pfaffian order.

cond-mat.mes-hall↗