A Fabry-Perot like two-photon interferometer for high-dimensional time-bin entanglement

We generate high-dimensional time-bin entanglement using a mode-locked laser and analyze it with a 2-photon Fabry-Perot interferometer. The dimension of the entangled state is limited only by the phase coherence between subsequent pulses and is practically infinite. In our experiment a pico-second mode-locked laser at 532 nm pumps a non-linear potassium niobate crystal to produce photon pairs by spontaneous parametric down-conversion at 810 and 1550 nm.Comment: 9 pages, 9 figure

Fast and simple one-way Quantum Key Distribution

We present and demonstrate a new protocol for practical quantum cryptography, tailored for an implementation with weak coherent pulses to obtain a high key generation rate. The key is obtained by a simple time-of-arrival measurement on the data line; the presence of an eavesdropper is checked by an interferometer on an additional monitoring line. The setup is experimentally simple; moreover, it is tolerant to reduced interference visibility and to photon number splitting attacks, thus featuring a high efficiency in terms of distilled secret bit per qubit.Comment: 4 pages, 4 figure

Quantum Random Number Generation Using a Quanta Image Sensor

A new quantum random number generation method is proposed. The method is based on the randomness of the photon emission process and the single photon counting capability of the Quanta Image Sensor (QIS). It has the potential to generate high-quality random numbers with remarkable data output rate. In this paper, the principle of photon statistics and theory of entropy are discussed. Sample data were collected with QIS jot device, and its randomness quality was analyzed. The randomness assessment method and results are discussed

Photon counting for quantum key distribution with Peltier cooled InGaAs/InP APD's

The performance of three types of InGaAs/InP avalanche photodiodes is investigated for photon counting at 1550 nm in the temperature range of thermoelectric cooling. The best one yields a dark count probability of $2.8\cdot 10^{-5}$ per gate (2.4 ns) at a detection efficiency of 10% and a temperature of -60C. The afterpulse probability and the timing jitter are also studied. The results obtained are compared with those of other papers and applied to the simulation of a quantum key distribution system. An error rate of 10% would be obtained after 54 kilometers.Comment: 8 pages, 10 figures, submitted to Journal of Modern Optic

Interférences quantiques : études et applications

Au cours du 19e siècle avec Young et Fresnel, puis par la suite avec Maxwell et sa théorie électromagnétique, une théorie moderne, ondulatoire permet de bien expliquer les phénomènes d'optique. Seuls le phénomène photoélectrique et la radiation du corps noir avec la catastrophe ultraviolette posaient encore quelques problèmes. En 1900, afin d'éliminer la catastrophe ultraviolette, Planck introduit l'idée que les radiations thermiques ne puissent être émises ou absorbées que sous forme de quanta discrets [1]. En 1905, parmi les quatre papiers révolutionnaires publiés par Einstein, l'un d'entre eux [2] pose véritablement les bases de la révolution de la mécanique quantique, la théorie qui décrit ce qu'il se passe au niveau des particules. Reprenant l'idée de Planck, Einstein explique que les corpuscules ou quanta de lumière ne découlent pas seulement d'astuces théoriques, mais que ces quanta représentent la lumière même. Il donne une explication complète de l'effet photoélectrique, ce qui lui vaudra le prix Nobel en 1921. En 1924, les quanta de lumière sont détectées directement pour la première fois par effet Compton (prix Nobel en 1927). En 1926, un chimiste, du nom de Lewis, introduit le nom « photon » pour qualifier les quanta de lumière..

Coherent one-way quantum key distribution

Quantum Key Distribution (QKD) consists in the exchange of a secrete key between two distant points [1]. Even if quantum key distribution systems exist and commercial systems are reaching the market [2], there are still improvements to be made: simplify the construction of the system; increase the secret key rate. To this end, we present a new protocol for QKD tailored to work with weak coherent pulses and at high bit rates [3]. The advantages of this system are that the setup is experimentally simple and it is tolerant to reduced interference visibility and to photon number splitting attacks, thus resulting in a high efficiency in terms of distilled secret bits per qubit. After having successfully tested the feasibility of the system [3], we are currently developing a fully integrated and automated prototype within the SECOQC project [4]. We present the latest results using the prototype. We also discuss the issue of the photon detection, which still remains the bottleneck for QKD

Quantum Random Number Generation Using a Quanta Image Sensor

A new quantum random number generation method is proposed. The method is based on the randomness of the photon emission process and the single photon counting capability of the Quanta Image Sensor (QIS). It has the potential to generate high-quality random numbers with remarkable data output rate. In this paper, the principle of photon statistics and theory of entropy are discussed. Sample data were collected with QIS jot device, and its randomness quality was analyzed. The randomness assessment method and results are discussed

Free-running InGaAs/InP avalanche photodiode with active quenching for single photon counting at telecom wavelengths

We present an InGaAs/InPavalanche photodiode with an active quenching circuit on an application specific integrated circuit (ASIC) that is capable of operating in both gated and free-running modes. The 1.6mm2 ASIC chip is fabricated using complementary metal oxide semiconductortechnology guaranteeing long-term stability, reliability, and compactness. In the free-running mode, we find a single photon detection efficiency of 10% with <2kHz of nois