QUROPE Quantum Information Processing and Communication in Europe

This one-day workshop on the physics, technology and application of single-photon detectors based on superconducting nanowires will take place on Friday September 23, 2011, in Eindhoven, The Netherlands. It will be a satellite workshop of the EUCAS 2011 - Superconductivity Centennial Conference (The Hague, September 18-23).

Article on research done by the group of prof. Jens Eisert, one of the scientists involved in Q-ESSENCE, highlighted at physicsworld.com.

Please find attached presentations from FET QIFT Open Day held at University of Warsaw, on April 15th, 2011.

The aim of this workshop is to bring together experts in different fields to compare experiences, approaches and strategies to control entanglement in different solid state quantum systems, such as nuclear & electronic spins, quantum dots & wires, superconducting & hybrid structures, impurities in solids, polaritons, etc. More specifically,
topics involved are:
-control, generation, robustness and transfer of entanglement;
-measurement of entanglement.

We report a 2 GHz operation of InGaAs avalanche photodiodes for efficient single photon detection at telecom wavelengths. Employing a self-differencing circuit that incorporates tuneability in both frequency and arm balancing, extremely weak avalanches can now be sensed so as to suppress afterpulsing. The afterpulse probability is characterized as 4.84% and 1.42% for a photon detection efficiency of 23.5% and 11.8%, respectively. The device will further increase the secure bit rate for fiber wavelength quantum key distribution.

[Correspondence]

We show that semiconductor avalanche photodiodes can exhibit diminutive amplification noise during the early evolution of avalanches. The noise is so low that the number of locally excited charges that seed each avalanche can be resolved. These findings constitute an important step towards realization of a solid-state noiseless amplifier for quantum information processing. Moreover, we believe that the experimental setup used, i.e., time-resolving locally excited avalanches, will become a useful tool for optimizing the number resolution.

We demonstrate a 1550 nm correlated photon-pair source in an integrated glass platform—a chalcogenide As2S3 waveguide. A measured pair coincidence rate of 80 s−1 was achieved using 57 mW of continuous-wave pump. The coincidence to accidental ratio was shown to be limited by spontaneous Raman scattering effects that are expected to be mitigated by using a pulsed pump source.

Photon sources for multi-photon entanglement experiments are commonly based on the process of spontaneous parametric down conversion. Due to the probabilistic photon production, such experiments suffer from low multiphoton count rates. To increase this count rate, we present a novel SPDC pump source based on a femtosecond UV enhancement cavity that increases the available pump power while maintaining a high repetition rate of 80MHz. We apply the cavity as photon source for realizing symmetric, multi-partite entangled Dicke states, which are observed with a high rate and high fidelity.