A quantum dot is a semiconductor heterostructure that confines charge carriers, electrons and holes, in a volume on the order of the particles’ de Broglie wavelength. Confinement at this scale results in discrete energy levels in a manner similar to that of electrons orbiting an atomic nucleus. A hole is the absence of an electron in the material, and the collective behavior of the nearby electrons makes the hole appear to be a particle unto itself. When an electron and a hole are simultaneously confined in a dot, they may recombine and emit the energy difference as a photon. The quantum mechanical state of the charge carriers trapped in the dot can be coherently manipulated by interactions with externally-applied laser beams and pulses. Therefore, this system, and a similar one where an additional electron is confined in the quantum dot, is potentially suitable as a quantum bit in a future quantum computer.
Current topics of interest include the coherence of single photons emitted by quantum dots, coherent control of electron spin degrees of freedom, and spin-photon interfaces.
After a B.S. in physics from MIT in 2001, Prof. Flagg received his Ph.D. from the University of Texas at Austin in 2008. He was a Postdoctoral Scholar and then Associate Researcher at the National Institute of Standards and Technology in Gaithersburg, MD from 2008 to 2012. He joined the faculty at WVU in the spring of 2013.