Towards single time-bin entangled photons from a quantum dot.

Harishankar Jayakumar, Ana Predojević, Thomas Kauten +3 more

Gregor Weihs, Tobias Huber, Ana Predojević

Christophe Couteau, Gregor Weihs

We present our results on fluorescence and photon statistics of quantum dots. We show evidence for photon antibunching and cross-correlation measurements within the biexciton-exciton cascade using a new set-up. We also discuss directions towards a demonstration of time-bin entangled photons from a single dot.

Y. Yamamoto, Matthew A. Pelton, Charles Santori +1 more

Marijn A. M. Versteegh, Michael E. Reimer, Aafke A. van den Berg +5 more

Time-bin-entangled photons are ideal for long-distance quantum communication via optical fibers. Here we present a source where, even at high creation rates, each excitation pulse generates, at most, one time-bin-entangled pair. This is important for the accuracy and security of quantum communication. Our site-controlled quantum dot generates single polarization-entangled photon pairs, which are then converted, without loss of entanglement strength, into single time-bin-entangled photon pairs.

Tobias Huber, Laurin Ostermann, Maximilian Prilmüller +4 more

We report a study on coherence of excitation of single quantum dots. We address the coherent excitation of biexcitons, the process that is indispensable for deterministic photon pair generation in quantum dots. Based on theoretical modeling we optimized the duration of the excitation pulse in our experiment to minimize the laser-induced dephasing and increase the biexciton-to-background single-exciton occupation probability. An additional effect of this approach is a high degree of time-bin entanglement with a concurrence of up to 0.78(6) and a 0.88(3) overlap with a maximally entangled state.