Integrated Sources of Entangled and Indistinguishable Photons
Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
Final Report Abstract
The D-A-CH project, with partners at the University of Innsbruck, the University of Würzburg and the Technische Universität Berlin, addressed two of the core challenges for the development of solid-state quantum light sources: The integration of a monolithic pump-laser with a solid state, on-chip single photon source, as well as a photon pair source, respectively. The implementation of the photon pair source was realized via an AlGaAs Bragg reflection waveguide (BRW), ensuring group velocity matching (quasi- phase matching) to enable efficient type-II parametric down conversion. The growth and fabrication technology required for the implementation of such BRWs was developed at the University of Würzburg, and the devices were successfully tested by the partner in Innsbruck. Jointly, we could demonstrate broadband indistinguishability of the converted photons, polarization entanglement as well as time-bin entanglement. In cooperation with the Berlin partner a unique photon number resolving transition edge sensor detection system was applied to explore the full photon statistics and photon-number parity of heralded single photons emitted by a BRW device. The project activities of the Berlin partner focused on the development of integrated sources of indistinguishable photons based on semiconductor quantum dots. In the underlying devices concept an on-chip integrated microlaser resonantly excites a single quantum dot in a nearby microcavity to emit single photons with high purity and high indistinguishability. This device concept was implemented jointly with the Würzburg partner who was responsible for the sample growth and processing, while the spectroscopic studies and the data evaluation was performed by the Berlin partner. The results obtained with respect to the integrated source of indistinguishable photons comprise the development of compact electrically driven microlasers with sub-GHz linewidth and threshold pump currents on the order of 10 µA. Such microlasers were integrated on-chip with quantum dot micropillar cavities acting as single-photon sources. In a groundbreaking experiment the microlasers were electrically pulsed to trigger the emission of single photons from the nearby quantum dot micropillar. Moreover, this coupled microlaser-micropillar assembly showed additional functionality and could be used as integrated photon-detector to monitor the laser intensity as well as an ultra-compact testbed for non-linear dynamics via on-chip electro-optical feedback. Beyond that, a microlaser was used for the first time to trigger the emission of single-photons of a quantum dot under strict resonant excitation into the s-shell of this twolevel system. Overall, the project has led to many groundbreaking results in the field of integrated quantum nanophotonics which can pave the way for ultra-compact quantum light sources emitting single photons and entangled photon pairs with close to ideal quantum properties in the future.
Publications
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A pulsed nonclassical light source driven by an integrated electrically triggered quantum dot microlaser, IEEE Journal of Selected Topics in Quantum Electronics 21, 1900609 (2015)
P. Munnelly, T. Heindel, M. M. Karow, S. Höfling, M. Kamp, C. Schneider, and S. Reitzenstein
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An electrically driven cavity-enhanced source of indistinguishable photons with 61% overall efficiency, APL Photonics 1, 011301 (2016)
A. Schlehahn, A. Thoma, P. Munnelly, M. Kamp, S. Höfling, T. Heindel, C. Schneider, and S. Reitzenstein
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Electrically Tunable Single-Photon Source Triggered by a Monolithically Integrated Quantum Dot Microlaser, ACS Photonics 4, 790 (2017)
P. Munnelly, T. Heindel, A. Thoma, M. Kamp, S. Höfling, C. Schneider, and S. Reitzenstein
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On-chip optoelectronic feedback in a micropillar laser-detector assembly, Optica 4, 303 (2017)
P. Munnelly, B. Lingnau, M. M. Karow, T. Heindel, M. Kamp, S. Höfling, K. Lüdge, C. Schneider, and S. Reitzenstein
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Quantum-optical spectroscopy of a two-level system using an electrically driven micropillar laser as a resonant excitation source, Light: Science & Applications 7, 41 (2018)
S. Kreinberg, T. Grbešić, M. Strauß, A. Carmele, M. Emmerling, C. Schneider, S. Höfling, X. Porte, and S. Reitzenstein
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Photon-number parity of heralded single photons from a Bragg-reflection waveguide reconstructed loss-tolerantly via moment generating function, New Journal of Physics 21, 103025 (2019)
K. Laiho, M. Schmidt, H. Suchomel, M. Kamp, S. Höfling, C. Schneider, J. Beyer, G. Weihs, and S. Reitzenstein
