1. The discovery of the fractional quantum Hall state at the quantum number 5/2 has reinvigorated studies of the two-dimensional electron gas. The prediction that this state has special, exotic properties similar to p-wave superconductors and that it supports a new type of non-Abelian statistics have generated much excitement. The agreement of the experimentally measured and theoretical predicted energy gaps for the 5/2 state is a necessary condition for such exotic behavior. Of the three studies done so far two find disagreement while one finds good agreement with predictions. Using a unique setup which enables resistance measurements and thermometry at 0.005 Kelvin [1], we have extended for the first time measurements of the 5/2 state to samples of very low densities and grown in different MBE chambers [2]. Based on our data we concluded that the two methods of analyzing the energy gaps which disagreed with the theory were faulty. The third method, however, gave an excellent agreement, strongly supporting therefore the exotic nature of the 5/2 state [2]. Fig.a Experimental setup enabling measurements at 0.005 Kelvin Fig.b Temperature measurement with a quartz tuning fork Fig.c Excellent agreement of measurement and theory [1] Samkharadze, Kumar, Manfra, Pfeiffer, West, Csathy, Review of Scientific Instruments 82, 053902 (2011) [2] Samkharadze et al., Physical Review B 84, 121305 (2011) The Energy Gap of the 5/2 Fractional Quantum Hall State Gabor Csathy, Purdue University, DMR 0907172 a b c

2. Education: Supported graduate students Nodar Samkharadze (2009-present) and Ethan Kleinbaum (summer 2012), undergraduate students Keith R. Miller (2011) and Celia Bernstein (REU summer 2012) and high school student: Franklin Talbert (2012) working with the PI received training in cryogenics and modern semiconductor science. As part of the NSF REU program at Purdue, during the summer of 2012 the PI worked with Celia Burnstein, an undergraduate from Loyola Marymount University in Los Angeles. Celia’s project involved correlating the strength of the disorder present in the electron gas and the strength of the fractional quantum Hall states. The PI has also mentored Franklin Talbert, a high school student from town. Franklin has learned about sound waves and has built an acoustic resonator used for measuring impurity concentrations in Helium gas. Since the fall of 2012 Franklin is a freshman at the Physics Department at Purdue and continues working with the PI. Nodar Julius Results from this project presented at: Princeton University (2012), Univ. of Florida, Gainesville (2012), APS March Meeting (2012), Korean Physics Symposium (2012), Univ. Of Chicago (2012), Sandia National Laboratories (2011), University of California Santa Barbara (2011), Univ. of Virginia-Charlottesville (2011), PennState (2011), Rice University (2011), Purdue (2011), EP2DS-19 Tallahassee (2011), APS March Meeting (2011) Celia Franklin The Energy Gap of the 5/2 Fractional Quantum Hall State Gabor Csathy, Purdue University, DMR 0907172