@article{62849,
  abstract     = {{<jats:title>Abstract</jats:title><jats:p>An on-demand source of bright entangled photon pairs is desirable for quantum key distribution (QKD) and quantum repeaters. The leading candidate to generate such pairs is based on spontaneous parametric down-conversion (SPDC) in non-linear crystals. However, its pair extraction efficiency is limited to 0.1% when operating at near-unity fidelity due to multiphoton emission at high brightness. Quantum dots in photonic nanostructures can in principle overcome this limit, but the devices with high entanglement fidelity (99%) have low pair extraction efficiency (0.01%). Here, we show a measured peak entanglement fidelity of 97.5% ± 0.8% and pair extraction efficiency of 0.65% from an InAsP quantum dot in an InP photonic nanowire waveguide. We show that the generated oscillating two-photon Bell state can establish a secure key for peer-to-peer QKD. Using our time-resolved QKD scheme alleviates the need to remove the quantum dot energy splitting of the intermediate exciton states in the biexciton-exciton cascade.</jats:p>}},
  author       = {{Pennacchietti, Matteo and Cunard, Brady and Nahar, Shlok and Zeeshan, Mohd and Gangopadhyay, Sayan and Poole, Philip J. and Dalacu, Dan and Fognini, Andreas and Jöns, Klaus and Zwiller, Val and Jennewein, Thomas and Lütkenhaus, Norbert and Reimer, Michael E.}},
  issn         = {{2399-3650}},
  journal      = {{Communications Physics}},
  number       = {{1}},
  publisher    = {{Springer Science and Business Media LLC}},
  title        = {{{Oscillating photonic Bell state from a semiconductor quantum dot for quantum key distribution}}},
  doi          = {{10.1038/s42005-024-01547-3}},
  volume       = {{7}},
  year         = {{2024}},
}

@article{20773,
  abstract     = {{<jats:title>Abstract</jats:title><jats:p>Semiconductor quantum dots are excellent candidates for ultrafast coherent manipulation of qubits by laser pulses on picosecond timescales or even faster. In inhomogeneous ensembles a macroscopic optical polarization decays rapidly due to dephasing, which, however, is reversible in photon echoes carrying complete information about the coherent ensemble dynamics. Control of the echo emission time is mandatory for applications. Here, we propose a concept to reach this goal. In a two-pulse photon echo sequence, we apply an additional resonant control pulse with multiple of 2<jats:italic>π</jats:italic> area. Depending on its arrival time, the control slows down dephasing or rephasing of the exciton ensemble during its action. We demonstrate for self-assembled (In,Ga)As quantum dots that the photon echo emission time can be retarded or advanced by up to 5 ps relative to its nominal appearance time without control. This versatile protocol may be used to obtain significantly longer temporal shifts for suitably tailored control pulses.</jats:p>}},
  author       = {{Kosarev, Alexander N. and Rose, Hendrik and Poltavtsev, Sergey V. and Reichelt, Matthias and Schneider, Christian and Kamp, Martin and Höfling, Sven and Bayer, Manfred and Meier, Torsten and Akimov, Ilya A.}},
  issn         = {{2399-3650}},
  journal      = {{Communications Physics}},
  number       = {{1}},
  title        = {{{Accurate photon echo timing by optical freezing of exciton dephasing and rephasing in quantum dots}}},
  doi          = {{10.1038/s42005-020-00491-2}},
  volume       = {{3}},
  year         = {{2020}},
}