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The Pancharatnam-Berry phase is a geometric phase acquired over a cycle of parameters in the Hamiltonian governing the evolution of the system. Here, we report on the observation of the Pancharatnam-Berry phase in a condensate of indirect excitons (IXs) in a GaAs-coupled quantum well structure. The Pancharatnam-Berry phase is directly measured by detecting phase shifts of interference fringes in IX interference patterns. Correlations are found between the phase shifts, polarization pattern of IX emission, and onset of IX spontaneous coherence. The evolving Pancharatnam-Berry phase is acquired due to coherent spin precession in IX condensate and is observed with no decay over lengths exceeding 10 μm indicating long-range coherent spin transport.

We present a concept and experimental proof of principle for split-gate devices for indirect excitons (IXs). The split-gate forms a narrow channel, a point contact, for IX current. Control of IX flow through the split-gate with both gate voltage and excitation power is demonstrated.

We present a method for determining correlations in a gas of indirect excitons in a semiconductor quantum well structure. The method involves subjecting the excitons to a periodic electrostatic potential that causes modulations of the exciton density and photoluminescence (PL). Experimentally measured amplitudes of energy and intensity modulations of exciton PL serve as an input to a theoretical estimate of the exciton correlation parameter and temperature. We also present a proof-of-principle demonstration of the method for determining the correlation parameter and discuss how its accuracy can be improved.

In this work, a zwitterlonic molecular micelle, poly-[epsilon]-sodium-undecanoyl lysinate (poly-[epsilon]-SUK), was synthesized and employed as a coating in open tubular capillary electrochromatography (OT-CEC) for protein separation. The zwitterionic poly-[epsilon]-SUK containing both carboxylic acid and amine groups can be either protonated or deprotonated depending on the pH of the background electrolyte; therefore, either an overall positively or negatively charged coating can be achieved. This zwitterionic coating allows protein separations in either normal or reverse polarity mode depending on the pH of the background electrolyte. The protein mixtures contained four basic proteins (lysozyme, cytochrome c, [alpha]-chymotrypsinogen A, and ribonuclease A) and six acidic proteins (myogiobin, deoxyribonuclease I, [beta]-lactoglobulin A, [beta]-lactoglobulin B, [alpha]-lactalbumin, and albumin). Protein separations were optimized specifically for acidic (reverse mode) and basic (normal mode) pH values. Varying the polymer thickness by changing the polymer and salt concentration had a great influence on protein resolution, while nearly all peaks were also baseline resolved in both modes using the optimized poly-[epsilon]-SUK coating concentration of 0.4% (w/v). Proteins in human sera were separated under optimized acidic and basic conditions in order to demonstrate the general utility of this coating. Nanoseale characterizations of the poly-[epsilon]-SUK micellar coatings on silicon surfaces were accomplished using atomic force microscopy (AFM) to gain insight into the morphology and thickness of the zwitterionic coating. The thickness of the polymer coating ranged from 0.9 to 2.4 nm based on local measurements using nanoshaving, an AFM-based method of nanolithography. 10.1021/ac902723n