Title: Flying Q-bits and entangled photons
Speaker: Prof. Dieter Bimberg
Time: 9:00(AM), Oct.22, 2009
Venue: Academic Meeting Room, Institute of Semiconductors, CAS
Abstract: Efficient generation of polarized single or entangled photons is the crucial requisite for novel quantum key distribution systems and quantum information processing. Single semiconductor quantum dots are capable of emitting such photons on demand using pulsed current injection.The realization of highly efficient electrically driven single photon sources (SPS) operating at very high repetition frequencies based on well established semiconductor technology is presented. The resulting resonant (Q =170) single-QD diode generates single polarized photons at a QDs grown on (111) oriented substrates of cubic semiconductors are proposed and demonstrated as source of entangled photon pairs. Intrinsic symmetry-lowering effects can be used for the generation of entangled photons without further tuning of the leading to the splitting of the exciton bright states are shown to be absent for this substrate orientation. As a result the biexciton to exciton recombination cascade of a QD fine-structure splitting via QD size and/or shape, as long as there are not large shape anisotropies. Complementary studies of c-plane GaN/AlN QDs reveal their potential as emitters of single or entangled photons still at high temperatures paving the way to true applications.
About speaker:Professor Dieter Bimberg received the Diploma in physics and the Ph.D. degree magna cum laude from Goethe University, Frankfurt, in 1968 and 1971, respectively. From 1972 to 1979 he held a Principal Scientist position at the Max Planck-Institute for Solid State Research in Grenoble/France and Stuttgart. In 1979 he was appointed as Professor of Electrical Engineering, Technical University of Aachen. Since 1981 he holds the Chair of Applied Solid State Physics at Technical University of Berlin. Since 1990 he is Executive Director of the Solid State Physics Institute at TU Berlin. Since 2004 he is director of the Center of Nanophotonics at TU Berlin. In 2006 he was elected as chairman of the German Government National Centers of Excellence of Nanotechnologies.