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  • 1
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    Direct observation of correlations between individual photon emission events of a microcavity laser (2009)
    Nature Publishing Group (NPG)
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    Publication Date: 2009-07-10
    Description: Lasers are recognized for coherent light emission, the onset of which is reflected in a change in the photon statistics. For many years, attempts have been made to directly measure correlations in the individual photon emission events of semiconductor lasers. Previously, the temporal decay of these correlations below or at the lasing threshold was considerably faster than could be measured with the time resolution provided by the Hanbury Brown/Twiss measurement set-up used. Here we demonstrate a measurement technique using a streak camera that overcomes this limitation and provides a record of the arrival times of individual photons. This allows us to investigate the dynamical evolution of correlations between the individual photon emission events. We apply our studies to micropillar lasers with semiconductor quantum dots as the active material, operating in the regime of cavity quantum electrodynamics. For laser resonators with a low cavity quality factor, Q, a smooth transition from photon bunching to uncorrelated emission with increasing pumping is observed; for high-Q resonators, we see a non-monotonic dependence around the threshold where quantum light emission can occur. We identify regimes of dynamical anti-bunching of photons in agreement with the predictions of a microscopic theory that includes semiconductor-specific effects.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wiersig, J -- Gies, C -- Jahnke, F -- Assmann, M -- Berstermann, T -- Bayer, M -- Kistner, C -- Reitzenstein, S -- Schneider, C -- Hofling, S -- Forchel, A -- Kruse, C -- Kalden, J -- Hommel, D -- England -- Nature. 2009 Jul 9;460(7252):245-9. doi: 10.1038/nature08126.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Physics Department, University of Bremen, 28334 Bremen, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19587766" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 2
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    Quantum-dot spin-photon entanglement via frequency downconversion to telecom wavelength (2012)
    Nature Publishing Group (NPG)
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    Publication Date: 2012-11-16
    Description: Long-distance quantum teleportation and quantum repeater technologies require entanglement between a single matter quantum bit (qubit) and a telecommunications (telecom)-wavelength photonic qubit. Electron spins in III-V semiconductor quantum dots are among the matter qubits that allow for the fastest spin manipulation and photon emission, but entanglement between a single quantum-dot spin qubit and a flying (propagating) photonic qubit has yet to be demonstrated. Moreover, many quantum dots emit single photons at visible to near-infrared wavelengths, where silica fibre losses are so high that long-distance quantum communication protocols become difficult to implement. Here we demonstrate entanglement between an InAs quantum-dot electron spin qubit and a photonic qubit, by frequency downconversion of a spontaneously emitted photon from a singly charged quantum dot to a wavelength of 1,560 nanometres. The use of sub-10-picosecond pulses at a wavelength of 2.2 micrometres in the frequency downconversion process provides the necessary quantum erasure to eliminate which-path information in the photon energy. Together with previously demonstrated indistinguishable single-photon emission at high repetition rates, the present technique advances the III-V semiconductor quantum-dot spin system as a promising platform for long-distance quantum communication.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉De Greve, Kristiaan -- Yu, Leo -- McMahon, Peter L -- Pelc, Jason S -- Natarajan, Chandra M -- Kim, Na Young -- Abe, Eisuke -- Maier, Sebastian -- Schneider, Christian -- Kamp, Martin -- Hofling, Sven -- Hadfield, Robert H -- Forchel, Alfred -- Fejer, M M -- Yamamoto, Yoshihisa -- England -- Nature. 2012 Nov 15;491(7424):421-5. doi: 10.1038/nature11577.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉E. L. Ginzton Laboratory, Stanford University, Stanford, California 94305, USA. kdegreve@stanford.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23151585" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 3
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    An electrically pumped polariton laser (2013)
    Nature Publishing Group (NPG)
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    Publication Date: 2013-05-17
    Description: Conventional semiconductor laser emission relies on stimulated emission of photons, which sets stringent requirements on the minimum amount of energy necessary for its operation. In comparison, exciton-polaritons in strongly coupled quantum well microcavities can undergo stimulated scattering that promises more energy-efficient generation of coherent light by 'polariton lasers'. Polariton laser operation has been demonstrated in optically pumped semiconductor microcavities at temperatures up to room temperature, and such lasers can outperform their weak-coupling counterparts in that they have a lower threshold density. Even though polariton diodes have been realized, electrically pumped polariton laser operation, which is essential for practical applications, has not been achieved until now. Here we present an electrically pumped polariton laser based on a microcavity containing multiple quantum wells. To prove polariton laser emission unambiguously, we apply a magnetic field and probe the hybrid light-matter nature of the polaritons. Our results represent an important step towards the practical implementation of polaritonic light sources and electrically injected condensates, and can be extended to room-temperature operation using wide-bandgap materials.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Schneider, Christian -- Rahimi-Iman, Arash -- Kim, Na Young -- Fischer, Julian -- Savenko, Ivan G -- Amthor, Matthias -- Lermer, Matthias -- Wolf, Adriana -- Worschech, Lukas -- Kulakovskii, Vladimir D -- Shelykh, Ivan A -- Kamp, Martin -- Reitzenstein, Stephan -- Forchel, Alfred -- Yamamoto, Yoshihisa -- Hofling, Sven -- England -- Nature. 2013 May 16;497(7449):348-52. doi: 10.1038/nature12036.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Technische Physik and Wilhelm-Conrad-Rontgen-Research Center for Complex Material Systems, Universitat Wurzburg, D-97074 Wurzburg, Am Hubland, Germany. christian.schneider@physik.uni-wuerzburg.de〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23676752" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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