Dr. Xiaoqin (Elaine) Li joined the physics department in January 2007 as an assistant professor in experimental condensed matter physics. She received her PhD in 2003 from the University of Michigan. She was a postdoctoral fellow from 2004 to 2006 at JILA, a joint institute of the National Institute of Standards and Technologies (NIST) and the University of Colorado. Her past work includes optically controlling single electrons for quantum information processing; she also worked on the development of novel spectroscopy methods based on ultrafast laser pulses. Since joining the department, Dr. Li has received a CAREER award from NSF, a Young Investigator Award from the Office of Naval Research and a Yound Investigator Award from the Air Force Office of Scientific Research. Dr. Li is also an Alfred P. Sloan Research Fellow.

The unifying theme of Dr. Li’s research is to study light-matter interaction in condensed matter systems in reduced dimensions. Currently, Dr. Li’s group is engaged in several research areas:

(i)Quantum dynamics in hybrid materials: There is an apparent size mismatch between modern electronic and photonic devices. While current electronic devices are routinely fabricated on the scale of tens of nanometers, photonic devices are limited to scales comparable to the wavelength of light — typically a few hundreds of nanometers — due to diffraction. We hope to circumvent this limitation by examining the interaction between illuminated semiconductor and metallic nanoparticles. Metallic nanoparticles (10nm to 100nm) provide the means to shape and guide optical fields on a smaller scale, moving beyond the diffraction limit.

(ii)Development of multi-dimensional spectroscopy: Imagine trying to read an article with the paper rolled up. This has to be a frustrating experience: there is limited information one can access at a glance and overlaps between the lines of text make it difficult to read clearly. Researchers using optical spectroscopy methods had to live with this predicament until the recent development of multi-dimensional spectroscopy. Using this new technique, we can now access information in two or higher dimensions, unraveling previously congested one-dimensional spectra. We are one of the first groups that are introducing this powerful concept to study semiconductors on ultrafast time scales. We hope to extend this method to the ultimate limit of studying a few quantum dots — essentially customized solid-state atoms.

(iii)Probing spin dynamics using light scattering techniques: The spin-transfer (or spin-torque) phenomenon refers to a novel method to manipulate spins in magnetic nanostructures using an electrical current. This effect offers unprecedented spatial and temporal control of spin distributions. We intend to shed new light on the underlying mechanisms of spin-torque phenomena using light-scattering techniques. An improved understanding of spin dynamics may lead to new generations of high-density magnetic memory devices (such as MRAM), magnetic field sensors, and high-frequency microwave resonators.