Prof. Harald Weinfurter Profile

Prof. Harald Weinfurter

Head of Experimental Quantum Physics at Ludwig Maximilians Univ Munchen

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Author

Publications (16)

Proceedings Article | 4 October 2024 Presentation + Paper

Prospects of scalable quantum key distribution using nano satellites

Lukas Knips, Michael Auer, Adomas Baliuka, Moritz Birkhold, Michael Steinberger, Harald Weinfurter

Proceedings Volume 13148, 1314808 (2024) https://doi.org/10.1117/12.3027336

KEYWORDS: Satellites, Quantum key distribution, Laser optics, Design, Vertical cavity surface emitting lasers, Semiconductor lasers, Integrated optics, Waveguides, Quantum systems, Quantum channels

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Proceedings Article | 7 October 2019 Paper

Stratospheric QKD: feasibility analysis and free-space optics system concept

Florian Moll, Thierry Botter, Christoph Marquardt, David Pusey, Amita Shrestha, Andrew Reeves, Kevin Jaksch, Kevin Gunthner, Oemer Bayraktar, Christian Mueller-Hirschkorn, Alberto Diago Gallardo, Dionisio Diaz Gonzalez, Wenjamin Rosenfeld, Peter Freiwang, Gerd Leuchs, Harald Weinfurter

Proceedings Volume 11167, 111670H (2019) https://doi.org/10.1117/12.2539076

KEYWORDS: Quantum key distribution, Free space optics, Telescopes, Adaptive optics, Electronics, Receivers, Atmospheric particles, Polarization, Atmospheric modeling, Telecommunications

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Quantum key distribution (QKD) is one of the most mature quantum technologies and can provide quantum-safe security in future communication networks. Since QKD in fiber is limited to a range of few hundred kilometers, one approach to bridge continental scale distances may be the use of high altitude pseudo satellites (HAPS) as mobile trusted nodes in the stratosphere. In parallel, free-space laser communication for high rate data transmission has been a subject of research and development for several decades and its commercialization is progressing rapidly. Important synergies exist between classical free-space communication and QKD systems since the quantum states are often implemented using the same degrees of freedom such as polarization or field amplitude and phase. These synergies can be used to benefit from the progress in classical free-space laser communication in QKD applications. In this paper, the use case of QKD in a stratospheric environment is described wherein HAPS may serve as relay station of secret keys and encrypted data. The mission scenario and HAPS capabilities are analyzed to derive special requirements on the stratospheric laser terminal, the link geometry and the ground segment with respect to a feasibility demonstration. To obtain a flexible and compatible system, discrete variable and continuous variable QKD protocols are considered to be implemented side by side in the HAPS payload. Depending on the system parameters, it can be beneficial to use the one or the other kind of protocol. Thus, a direct comparison of both in one and the same system is of scientific interest. Each of the protocols has particular requirements on coupling efficiency and implementation. Link budget calculations are performed to analyze possible distances, key rates and data transmission rates for the different schemes. In case of the QKD system, the mean coupling efficiency is of main interest, i.e. signal fluctuations arising from atmospheric turbulence must be taken into account in the security proof, but the buffered key generation relaxes real-time requirements. This is different to classical communications, where the corresponding fading loss must be assessed. A system architecture is presented that comprises the optical aircraft terminal, the optical ground terminal and the most important subsystems that enable implementation of the considered QKD protocols. The aircraft terminal is interfaced with the dedicated quantum transmitter module (Alice) and the ground station with the dedicated quantum receiver module (Bob). The optical interfaces are SMF couplings which put high requirements on the receiving optics, in particular the need for wave-front correction with adaptive optics. The findings of the system study are reviewed and necessary next steps pointed out.

Proceedings Article | 21 November 2017 Open Access

QIPS: quantum information and quantum physics in space

Tobias Schmitt-Manderbach, Thomas Scheidl, Rupert Ursin, Felix Tiefenbacher, Henning Weier, Martin Fürst, T. Jennewein, J. Perdigues, Z. Sodnik, J. Rarity, Anton Zeilinger, Harald Weinfurter

Proceedings Volume 10567, 1056728 (2017) https://doi.org/10.1117/12.2308067

KEYWORDS: Receivers, Single photon, Transmitters, Polarization, Telescopes, Photons, Signal attenuation, Quantum information, Quantum physics, Quantum communications

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Proceedings Article | 29 April 2016 Paper

Aerospace laser communications technology as enabler for worldwide quantum key distribution

Florian Moll, Harald Weinfurter, Markus Rau, Christopher Schmidt, Gwen Melén, Tobias Vogl, Sebastian Nauerth, Christian Fuchs

Proceedings Volume 9900, 99000K (2016) https://doi.org/10.1117/12.2230232

KEYWORDS: Quantum key distribution, Satellites, Laser communications, Aerospace engineering, Free space optics, Satellite communications, Receivers, Polarization, Telecommunications, Telescopes

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A worldwide growing interest in fast and secure data communications pushes technology development along two lines. While fast communications can be realized using laser communications in fiber and free-space, inherently secure communications can be achieved using quantum key distribution (QKD). By combining both technologies in a single device, many synergies can be exploited, therefore reducing size, weight and power of future systems. In recent experiments we demonstrated quantum communications over large distances as well as between an aircraft and a ground station which proved the feasibility of QKD between moving partners. Satellites thus may be used as trusted nodes in combination with QKD receiver stations on ground, thereby enabling fast and secure communications on a global scale. We discuss the previous experiment with emphasis on necessary developments to be done and corresponding ongoing research work of German Aerospace Center (DLR) and Ludwig Maximilians University Munich (LMU). DLR is performing research on satellite and ground terminals for the high-rate laser communication component, which are enabling technologies for the QKD link. We describe the concept and hardware of three generations of OSIRIS (Optical High Speed Infrared Link System) laser communication terminals for low Earth orbiting satellites. The first type applies laser beam pointing solely based on classical satellite control, the second uses an optical feedback to the satellite bus and the third, currently being in design phase, comprises of a special coarse pointing assembly to control beam direction independent of satellite orientation. Ongoing work also targets optical terminals for CubeSats. A further increase of beam pointing accuracy can be achieved with a fine pointing assembly. Two ground stations will be available for future testing, an advanced stationary ground station and a transportable ground station. In parallel the LMU QKD source size will be reduced by more than an order of magnitude thereby simplifying its integration into future free-space optical communication links with CubeSats.

Proceedings Article | 15 March 2016 Paper

Integrated quantum key distribution sender unit for daily-life implementations

Gwenaelle Mélen, Tobias Vogl, Markus Rau, Giacomo Corrielli, Andrea Crespi, Roberto Osellame, Harald Weinfurter

Proceedings Volume 9762, 97620A (2016) https://doi.org/10.1117/12.2208643

KEYWORDS: Quantum key distribution, Quantum communications, Transmitters, Receivers, Polarization, Mobile devices, Integrated optics, Information security, Vertical cavity surface emitting lasers, Beam splitters

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Proceedings Article | 26 September 2013 Paper

Breaking the diffraction limit using entanglement based microscopy

Daniel Schlenk, Harald Weinfurter

Proceedings Volume 8875, 887509 (2013) https://doi.org/10.1117/12.2023010

KEYWORDS: Photons, Single photon, Gold, Microscopes, Crystals, Laser crystals, Two photon excitation microscopy, Microscopy, Glasses, Light sources

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Proceedings Article | 25 October 2012 Paper

Air to ground quantum key distribution

Sebastian Nauerth, Florian Moll, Markus Rau, Joachim Horwath, Stefan Frick, Christian Fuchs, Harald Weinfurter

Proceedings Volume 8518, 85180D (2012) https://doi.org/10.1117/12.929790

KEYWORDS: Quantum key distribution, Satellites, Mirrors, Polarization, Quantum communications, Satellite communications, Telecommunications, Signal attenuation, Stray light, Transmitters

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Proceedings Article | 24 October 2012 Paper

Communication system technology for demonstration of BB84 quantum key distribution in optical aircraft downlinks

Florian Moll, Sebastian Nauerth, Christian Fuchs, Joachim Horwath, Markus Rau, Harald Weinfurter

Proceedings Volume 8517, 851703 (2012) https://doi.org/10.1117/12.929739

KEYWORDS: Quantum key distribution, Telecommunications, Receivers, Polarization, Telescopes, Signal attenuation, Transmitters, Scintillation, Space telescopes, Free space optics

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Proceedings Article | 5 June 2010 Open Access

Six-photon entangled Dicke state enabled by a UV enhancement cavity as novel SPDC photon source

Witlef Wieczorek, Roland Krischek, Akira Ozawa, Géza Tóth, Nikolai Kiesel, Patrick Michelberger, Thomas Udem, Harald Weinfurter

Proceedings Volume 7727, 77270L (2010) https://doi.org/10.1117/12.853599

KEYWORDS: Ultraviolet radiation, Mirrors, Quantum information, Crystals, Nonlinear crystals, Dispersion, Photonic crystals, Quantum communications, Photon polarization, Femtosecond phenomena

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Proceedings Article | 23 January 2010 Paper

Entanglement enhanced quantum sensing

W. Wieczorek, R. Krischek, N. Kiesel, Ch. Schmid, H. Weinfurter

Proceedings Volume 7608, 76080P (2010) https://doi.org/10.1117/12.837531

KEYWORDS: Photons, Polarization, Metrology, Quantum information, Phase shifts, Crystals, Beam splitters, Sensors, Entangled states, Quantum optics

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Proceedings Article | 10 September 2007 Paper

Multiphoton entanglement engineering via projective measurements

Christian Schmid, Nikolai Kiesel, Witlef Wieczorek, Reinhold Pohlner, Harald Weinfurter

Proceedings Volume 6780, 67800E (2007) https://doi.org/10.1117/12.734697

KEYWORDS: Photon polarization, Polarization, Quantum communications, Entangled states, Beam splitters, Crystals, Single photon, Stochastic processes, Wave plates, Superposition

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Proceedings Article | 16 October 2006 Paper

Free-space quantum cryptography for metropolitan areas

M. Fürst, T. Schmitt-Manderbach, H. Weier, I. Ordavo, H. Weinfurter

Proceedings Volume 6399, 63990I (2006) https://doi.org/10.1117/12.690184

KEYWORDS: Photons, Receivers, Polarization, Quantum key distribution, Transmitters, Free space, Telescopes, Single photon, Quantum cryptography, Space telescopes

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Proceedings Article | 16 October 2006 Paper

Free-space quantum key distribution over 144 km

M. Fürst, H. Weier, T. Schmitt-Manderbach, R. Ursin, F. Tiefenbacher, T. Scheidl, M. Lindenthal, B. Blauensteiner, T. Jennewein, P. Trojek, J. Perdigues, Z. Sodnik, C. Barbieri, J. Rarity, A. Zeilinger, H. Weinfurter

Proceedings Volume 6399, 63990G (2006) https://doi.org/10.1117/12.690174

KEYWORDS: Photons, Telescopes, Polarization, Transmitters, Quantum key distribution, Space telescopes, Optical tracking, Satellites, Receivers, Free space optics

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Proceedings Article | 3 February 2004 Paper

Quantum communications in space

John Rarity, Phil Gorman, P. Knight, Harald Weinfurter, Christian Kurtsiefer

Proceedings Volume 5161, (2004) https://doi.org/10.1117/12.504744

KEYWORDS: Satellites, Quantum communications, Polarization, Teleportation, Receivers, Quantum cryptography, Entangled states, Telescopes, Space telescopes, Sensors

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Proceedings Article | 13 September 2002 Paper

Multiphoton entanglement

Mohamed Bourennane, Manfred Eibl, Sascha Gaertner, Nicolai Kiesel, Christian Kurtsiefer, Marek Zukowski, Harald Weinfurter

Proceedings Volume 4917, (2002) https://doi.org/10.1117/12.483039

KEYWORDS: Quantum communications, Polarization, Entangled states, Beam splitters, Photon polarization, Correlation function, Quantum physics, Quantum mechanics, Teleportation, Optical filters

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Proceedings Article | 13 September 2002 Paper

Long-distance free-space quantum cryptography

Christian Kurtsiefer, P. Zarda, M. Halder, Ph. Gorman, Paul Tapster, J. Rarity, Harald Weinfurter

Proceedings Volume 4917, (2002) https://doi.org/10.1117/12.483036

KEYWORDS: Receivers, Polarization, Photons, Quantum cryptography, Spatial filters, Transmitters, Telescopes, Sensors, Semiconductor lasers, Beam splitters

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Showing 5 of 16 publications

Conference Committee Involvement (4)

Quantum Communications Realized II

28 January 2009 | San Jose, California, United States

Quantum Communications Realized

10 September 2007 | Boston, MA, United States

Quantum Optics and Quantum Cryptography

18 April 2007 | Prague, Czech Republic

Advanced Free-Space Optical Communication Techniques and Applications III

13 September 2006 | Stockholm, Sweden

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