@article{YuNatarajanHorikirietal.2015,
  author    = {Yu, Leo and Natarajan, Chandra M. and Horikiri, Tomoyuki and Langrock, Carsten and Pelc, Jason S. and Tanner, Michael G. and Abe, Eisuke and Maier, Sebastian and Schneider, Christian and H{\"o}fling, Sven and Kamp, Martin and Hadfield, Robert H. and Fejer, Martin M. and Yamamoto, Yoshihisa},
  title     = {Two-photon interference at telecom wavelengths for time-bin-encoded single photons from quantum-dot spin qubits},
  series = {Nature Communications},
  volume    = {6},
  journal   = {Nature Communications},
  doi       = {10.1038/ncomms9955},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-138677},
  pages     = {8955},
  year      = {2015},
  abstract  = {Practical quantum communication between remote quantum memories rely on single photons at telecom wavelengths. Although spin-photon entanglement has been demonstrated in atomic and solid-state qubit systems, the produced single photons at short wavelengths and with polarization encoding are not suitable for long-distance communication, because they suffer from high propagation loss and depolarization in optical fibres. Establishing entanglement between remote quantum nodes would further require the photons generated from separate nodes to be indistinguishable. Here, we report the observation of correlations between a quantum-dot spin and a telecom single photon across a 2-km fibre channel based on time-bin encoding and background-free frequency downconversion. The downconverted photon at telecom wavelengths exhibits two-photon interference with another photon from an independent source, achieving a mean wavepacket overlap of greater than 0.89 despite their original wavelength mismatch (900 and 911 nm). The quantum-networking operations that we demonstrate will enable practical communication between solid-state spin qubits across long distances.},
  language  = {en}
}
@article{WinklerFischerSchadeetal.2015,
  author    = {Winkler, Karol and Fischer, Julian and Schade, Anne and Amthor, Matthias and Dall, Robert and Geßler, Jonas and Emmerling, Monika and Ostrovskaya, Elena A. and Kamp, Martin and Schneider, Christian and H{\"o}fling, Sven},
  title     = {A polariton condensate in a photonic crystal potential landscape},
  series = {New Journal of Physics},
  volume    = {17},
  journal   = {New Journal of Physics},
  doi       = {10.1088/1367-2630/17/2/023001},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-125050},
  pages     = {023001},
  year      = {2015},
  abstract  = {The possibility of investigating macroscopic coherent quantum states in polariton condensates and of engineering polariton landscapes in semiconductors has triggered interest in using polaritonic systems to simulate complex many-body phenomena. However, advanced experiments require superior trapping techniques that allow for the engineering of periodic and arbitrary potentials with strong on-site localization, clean condensate formation, and nearest-neighbor coupling. Here we establish a technology that meets these demands and enables strong, potentially tunable trapping without affecting the favorable polariton characteristics. The traps are based on a locally elongated microcavity which can be formed by standard lithography. We observe polariton condensation with non-resonant pumping in single traps and photonic crystal square lattice arrays. In the latter structures, we observe pronounced energy bands, complete band gaps, and spontaneous condensation at the M-point of the Brillouin zone.},
  language  = {en}
}
@article{MaierGoldForcheletal.2014,
  author    = {Maier, Sebastian and Gold, Peter and Forchel, Alfred and Gregersen, Niels and Mork, Jesper and H{\"o}fling, Sven and Schneider, Christian and Kamp, Martin},
  title     = {Bright single photon source based on self-aligned quantum dot-cavity systems},
  series = {Optics Express},
  volume    = {22},
  journal   = {Optics Express},
  number    = {7},
  issn      = {1094-4087},
  doi       = {10.1364/OE.22.008136},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-119801},
  pages     = {8136-42},
  year      = {2014},
  abstract  = {We report on a quasi-planar quantum-dot-based single-photon source that shows an unprecedented high extraction efficiency of 42\% without complex photonic resonator geometries or post-growth nanofabrication. This very high efficiency originates from the coupling of the photons emitted by a quantum dot to a Gaussian shaped nanohill defect that naturally arises during epitaxial growth in a self-aligned manner. We investigate the morphology of these defects and characterize the photonic operation mechanism. Our results show that these naturally arising coupled quantum dot-defects provide a new avenue for efficient (up to 42\% demonstrated) and pure (g(2)(0) value of 0.023) single-photon emission.},
  language  = {en}
}
@article{RauHeindelUnsleberetal.2014,
  author    = {Rau, Markus and Heindel, Tobias and Unsleber, Sebastian and Braun, Tristan and Fischer, Julian and Frick, Stefan and Nauerth, Sebastian and Schneider, Christian and Vest, Gwenaelle and Reitzenstein, Stephan and Kamp, Martin and Forchel, Alfred and H{\"o}fling, Sven and Weinfurter, Harald},
  title     = {Free space quantum key distribution over 500 meters using electrically driven quantum dot single-photon sources-a proof of principle experiment},
  series = {New Journal of Physics},
  volume    = {16},
  journal   = {New Journal of Physics},
  number    = {043003},
  doi       = {10.1088/1367-2630/16/4/043003},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-116760},
  year      = {2014},
  abstract  = {Highly efficient single-photon sources (SPS) can increase the secure key rate of quantum key distribution (QKD) systems compared to conventional attenuated laser systems. Here we report on a free space QKD test using an electrically driven quantum dot single-photon source (QD SPS) that does not require a separate laser setup for optical pumping and thus allows for a simple and compact SPS QKD system. We describe its implementation in our 500 m free space QKD system in downtown Munich. Emulating a BB84 protocol operating at a repetition rate of 125 MHz, we could achieve sifted key rates of 5-17 kHz with error ratios of 6-9\% and g((2))(0)-values of 0.39-0.76.},
  language  = {en}
}
@article{AmthorWeissenseelFischeretal.2014,
  author    = {Amthor, Matthias and Weißenseel, Sebastian and Fischer, Julian and Kamp, Martin and Schneider, Christian and H{\"o}fling, Sven},
  title     = {Electro-optical switching between polariton and cavity lasing in an InGaAs quantum well microcavity},
  doi       = {10.1364/OE.22.031146},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-111130},
  year      = {2014},
  abstract  = {We report on the condensation of microcavity exciton polaritons under optical excitation in a microcavity with four embedded InGaAs quantum wells. The polariton laser is characterized by a distinct nonlinearity in the input-output-characteristics, which is accompanied by a drop of the emission linewidth indicating temporal coherence and a characteristic persisting emission blueshift with increased particle density. The temporal coherence of the device at threshold is underlined by a characteristic drop of the second order coherence function to a value close to 1. Furthermore an external electric field is used to switch between polariton regime, polariton condensate and photon lasing.},
  language  = {en}
}