Condensed Matter Physics Seminar

Thirty years after its initial discovery, the fractional quantum Hall effects continues to challenge our understanding of electronic correlations. Presently, the fragile ν=5/2 fractional quantum Hall state is the subject of intense scrutiny. It is theoretically conjectured that the ν=5/2 state is described by the Moore-Read Pfaffian wavefunction, possessing excitations obeying non-Abelian braiding statistics. If experimentally confirmed, excitations with non-Abelian braiding statistics may provide a platform for proposed schemes of topologically-protected quantum computing. While there are many aspects to the physics at ν=5/2 the role of disorder remains still poorly understood. The measured excitation gap at ν=5/2 remains rather small, ~0.5K at best. This limit does not yet appear fundamental as general improvements in sample quality continue to result in larger experimental gaps. However we lack a detailed understanding of what types of disorder are most detrimental to the ν=5/2 state. Our ongoing work at Purdue focuses on trying to understand the impact of disorder, ever present in real samples, on the ν=5/2 state. I will describe our attempts to isolate the most important types of disorder and our metrics used to determine if a sample is likely to have a strong state at ν=5/2. Our goal is to provide a means by which future samples can be designed to host exotic correlated states.