Optical Preparation and Manipulation of Entangled Spin States in Quantum Dot Molecules Eric Stinaff, Ohio University, DMR 1005525.
In low dimensional systems the discrete nature of the energy levels restricts the processes through which relaxation can occur. In quantum dot molecules (QDMs) the dominant scattering mechanism involves acoustic phonons. In these QDMs the molecular states, where the carrier wavefunction is spatially delocalized between the dots, the carrier-phonon interaction is modified, providing a useful method for tuning important properties.
Theoretical investigations have suggested that a reduction of acoustic phonon scattering rates can be achieved in QDMs. We have observed evidence of such a modulation and found that the measured lifetime can be understood as a combination of a changing wavefunction, carrier tunneling, and phonon relaxation. We have also observed controllable modulations in the polarized emission due to variations in the anisotropic exchange interaction, possibly useful for entangled photon generation.
(a) PL spectra, as a function of electric field, relative to the neutral exciton. (b) Relative indirect exciton intensity. (c) Indirect exciton lifetime fluctuation relative to the exciton energy separation. (d) Circular polarization memory.
The expanded panel shows the various rates contributing to relaxation along with a comparison with theory.
Juan E. Rolon, Kushal C. Wijesundara, Sergio E. Ulloa, Allan S. Bracker, Daniel Gammon, Eric A. Stinaff, J. Opt. Soc. Am. B29, A146 (2012)
Kushal C. Wijesundara, Juan E. Rolon, Sergio E. Ulloa, Allan S. Bracker, Daniel Gammon, Eric A. Stinaff, Phys. Rev. B84, 081404(R) (2011)
Optical Preparation and Manipulation of Entangled Spin States in Quantum Dot MoleculesEric Stinaff, Ohio University, DMR 1005525
The PI has developed a well received presentation, titled “Sharks with Lasers on Their Heads!”, for the bi-annual Ohio University Department of Physics and Astronomy Open House. Attended by over 200 people throughout the day, the presentation gave an introduction to lasers and their applications to a general audience ranging from grade school children to adults. This presentation was featured in a video on the department’s YouTube channel.
Two Ph.D. students, partially supported by this grant, have graduated. Kushal Wijesundara successfully defended his Ph.D. dissertation in June 2012 and is currently a postdoctoral researcher at the University of North Carolina at Chapel Hill building and characterizing Optical Coherence Tomography imaging systems. Swati Ramanathan successfully defended her Ph.D. dissertation in March 2012 and is a researcher with KLA Tencor in California working on automated optical wafer inspection systems.
Gumi Bear being hit with a 10W, 532nm laser from a video shown at the 2011 Physics & Astronomy Open House.
Below: Kushal Wijesundara in the lab. Right: Swati Ramanathan discussing spin effects in quantum dots at a weekly group meeting.
Photo credit: Lydia Deakin
Photo credit: John Stoops