This award supports theoretical research and education to investigate possible exciton superfluids in two quasi-two-dimensional semiconductor gallium arsenide/aluminum gallium arsenide systems: electron-hole coupled bilayers and electron-electron coupled bilayers at quantum Hall regime at total filling factor 1.
The research has three parts:
(1) The PI will investigate photoluminescence from the quantum phases of excitons in electron-hole coupled bilayers, especially the exciton superfluids, in experimentally relevant environments. The PI will investigate the effect of an in-plane magnetic field and quenched disorder. Photoluminescence includes all the photon characteristics such as the angle resolved power spectrum, the momentum distribution curve, the energy distribution curve, the two modes squeezing spectrum, and two-photon correlation functions. The PI will also study how the photoluminescence can detect a novel quantum phase diffusion process of exciton superfluids inside a harmonic trap.
(2) The PI will study Coulomb drag properties of gate voltage generated excitons in the electron-hole coupled bilayers.
(3) Informed by the results of (1), the PI will revisit outstanding unresolved phenomena involving the transport properties of possible exciton superfluids in the electron-electron coupled quantum Hall bilayers.
This award supports training graduate students in theoretical and computational materials research.
NONTECHNICAL SUMMARY
This award supports theoretical research and education to investigate superfluidity in semiconductor systems. Superfluidity is a phase of matter in which certain fluids are able to overcome friction and flow through a narrow channel without any viscosity. The ability of superfluids to flow without any resistance can allow them to have a variety of important technological applications. However, superfluidity has so far been observed in very few systems such as liquids of the element Helium cooled to near the absolute zero of temperature. Experimentalists are searching for superfluids made of excitons. An exciton is a bound state of an excited electron and a "hole;? it is created when light interacts with semiconductors or insulators and excites an electron from an occupied quantum state to an unoccupied one, leaving behind an effective positive charge called the hole. The electrostatic interaction between the negatively charged electron and the positively charged hole stabilizes the exciton. Although no exciton superfluid phase has yet been observed in any bulk system, recently, exciton systems have been experimentally produced by many groups using different methods in almost-two-dimensional artificial materials made from semiconductors. There is good evidence that it might be possible to experimentally observe exciton superfluidity in such systems.
This award supports theoretical research and education on exciton superfluids in artificially fabricated semiconductor structures. The PI will study theoretically all the possible new and unique features of light emission processes and transport properties in exciton superfluids. The study involves combination of advanced techniques from two branches of physics: many body theory and quantum optics. The PI's theoretical study is expected to guide experimentalists to realize, control, and especially detect these exotic quantum phases in the laboratory. The research has fundamental importance, experimental relevance, and potential industrial applications.
This award supports training graduate students in theoretical and computational materials research.
