Hugo Zbinden

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A physical random number generator based on the intrinsic randomness of quantum mechanics is described. The random events are realized by the choice of single photons between the two outputs of a beamsplitter. We present a simple device, which minimizes the impact of the photon counters’ noise, dead-time and after pulses. Random numbers are employed today(More)
We investigate the performance of separate absorption multiplication InGaAs/InP avalanche photodiodes as single-photon detectors for 1.3- and 1.55-mum wavelengths. First we study afterpulses and choose experimental conditions to limit this effect. Then we compare the InGaAs/InP detector with a germanium avalanche photodiode; the former shows a lower(More)
Quantum communication requires the transfer of quantum states, or quantum bits of information (qubits), from one place to another. From a fundamental perspective, this allows the distribution of entanglement and the demonstration of quantum non-locality over significant distances. Within the context of applications, quantum cryptography offers a provably(More)
Quantum Key Distribution (QKD), the most advanced technology of the field of quantum information, allows two remote parties to exchange a sequence of random bits and subsequently check their secrecy [1]. It has been extensively tested in the past couple of years over distances of a few tens of kilometers [2–6]. Its security relies on the fact that the bits(More)
We experimentally demonstrate an integrated semiconductor source of counterpropagating twin photons in the telecom range. A pump beam impinging on top of an AlGaAs waveguide generates parametrically two counterpropagating, orthogonally polarized signal/idler guided modes. A 2 mm long waveguide emits at room temperature one average photon pair per pump(More)
We present a time-multiplexed interferometer based on Faraday mirrors, and apply it to quantum key distribution. The interfering pulses follow exactly the same spatial path, ensuring very high stability and self balancing. Use of Faraday mirrors compensates automatically any birefringence effects and polarization dependent losses in the transmitting fiber.(More)
We propose a quantum repeater protocol which builds on the well-known Duan-Lukin-Cirac-Zoller (DLCZ) protocol [L. M. Duan, M. D. Lukin, J. I. Cirac, and P. Zoller, Nature (London) 414, 413 (2001)10.1038/35106500], but which uses photon pair sources in combination with memories that allow to store a large number of temporal modes. We suggest to realize such(More)
Markus Jakobi,1,2 Christoph Simon,1,3 Nicolas Gisin,1 Jean-Daniel Bancal,1 Cyril Branciard,1 Nino Walenta,1 and Hugo Zbinden1 1Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland 2Humboldt-Universität zu Berlin, D-10117 Berlin, Germany 3Institute for Quantum Information Science and Department of Physics and Astronomy, University of(More)
Bit commitment is a fundamental cryptographic primitive in which Alice wishes to commit a secret bit to Bob. Perfectly secure bit commitment between two mistrustful parties is impossible through an asynchronous exchange of quantum information. Perfect security is, however, possible when Alice and Bob each split into several agents exchanging classical(More)