32 Bin Near-Infrared Time-Multiplexing Detector with Attojoule Single-Shot Energy Resolution

We present two implementations of photon counting time-multiplexing detectors for near-infrared wavelengths, based on Peltier cooled InGaAs/InP avalanche photo diodes (APDs). A first implementation is motivated by practical considerations using only commercially available components. It features 16 bins, pulse repetition rates of up to 22 kHz and a large range of applicable pulse widths of up to 100 ns. A second implementation is based on rapid gating detectors, permitting deadtimes below 10 ns. This allows one to realize a high dynamic-range 32 bin detector, able to process pulse repetition rates of up to 6 MHz for pulse width of up to 200 ps. Analysis of the detector response at 16.5% detection efficiency, reveals a single-shot energy resolution on the attojoule level.Comment: 7 pages, 7 figure

Non-local two-photon correlations using interferometers physically separated by 35 meters

An experimental demonstration of quantum correlations is presented. Energy and time entangled photons at wavelengths of 704 and 1310 nm are produced by parametric downconversion in KNbO3 and are sent through optical fibers into a bulk-optical (704 nm) and an all-fiber Michelson-interferometer (1310 nm), respectively. The two interferometers are located 35 meters aside from one another. Using Faraday-mirrors in the fiber-interferometer, all birefringence effects in the fibers are automatically compensated. We obtained two-photon fringe visibilities of up to 95 % from which one can project a violation of Bell's inequality by 8 standard deviations. The good performance and the auto-aligning feature of Faraday-mirror interferometers show their potential for a future test of Bell's inequalities in order to examine quantum-correlations over long distances.Comment: 9 pages including 3 postscript figures, to be published in Europhys. Let

Energy-time entangled qutrits: Bell tests and quantum communication

We have developed a scheme to generate, control, transmit and measure entangled photonic qutrits (two photons each of dimension d = 3). A Bell test of this source has previously been reported elsewhere [1], therefore, here we focus on how the control of the system is realized. Motivated by these results, we outline how the scheme can be used for two specific quantum protocols, namely key distribution and coin tossing and discuss some of their advantages and disadvantages.Comment: For the conference proceedings of QCMC 200

Experimental Test of Relativistic Quantum State Collapse with Moving Reference Frames

An experimental test of relativistic wave-packet collapse is presented. The tested model assumes that the collapse takes place in the reference frame determined by the massive measuring detectors. Entangled photons are measured at 10 km distance within a time interval of less than 5 ps. The two apparatuses are in relative motion so that both detectors, each in its own inertial reference frame, are first to perform the measurement. The data always reproduces the quantum correlations and thus rule out a class of collapse models. The results also set a lower bound on the "speed of quantum information" to 0.66 x 10^7 and 1.5 x 10^4 times the speed of light in the Geneva and the background radiation reference frames, respectively. The very difficult and deep question of where the collapse takes place - if it takes place at all - is considered in a concrete experimental context.Comment: 4 pages + 2 ps figure

A Bell-type test of energy-time entangled qutrits

We have performed a Bell-type test for energy-time entangled qutrits. A method of inferring the Bell violation in terms of an associated interference visibility is derived. Using this scheme we obtained a Bell value of $2.784 \pm 0.023$, representing a violation of $34 \sigma$ above the limit for local variables. The scheme has been developed for use at telecom wavelengths and using proven long distance quantum communication architecture to optimize the utility of this high dimensional entanglement resource.Comment: replaced lost acknowledement

Lorentz transformations of open systems

We consider open dynamical systems, subject to external interventions by agents that are not completely described by the theory (classical or quantal). These interventions are localized in regions that are relatively spacelike. Under these circumstances, no relativistic transformation law exists that relates the descriptions of the physical system by observers in relative motion. Still, physical laws are the same in all Lorentz frames.Comment: Final version submitted to J. Mod. Opt. (Proc. of Gdansk conference

Relativity and EPR Entanglement: Comments

Recent experiment by Zhinden et al (Phys. Rev {\bf A} 63 02111, 2001) purports to test compatibility between relativity and quantum mechanics in the classic EPR setting. We argue that relativity has no role in the EPR argument based solely on non-relativistic quantum formalism. It is suggested that this interesting experiment may have significance to address fundamental questions on quantum probability.Comment: 6 pages, no figure; Submitted to Phys. Rev.

Extended-spectrum β-lactamase-producing Gram-negative pathogens in community-acquired urinary tract infections: an increasing challenge for antimicrobial therapy

Background: Extended-spectrum β-lactamases (ESBLs) are an increasing challenge in the treatment of urinary tract infections (UTIs), and also in the community. We aimed to investigate the characteristics of patients with UTIs due to ESBL-producing Escherichia coli and to assess the risk factors for ESBLs in community-acquired isolates. Methods: We performed a retrospective study from January 1, 2007 to December 31, 2009 at a tertiary care teaching hospital in Switzerland, comparing patients with community-acquired versus healthcare-associated UTIs due to ESBL-producing E. coli. Additionally, we investigated the antimicrobial susceptibility of these isolates. Results: A total of 123 patients were studied, of whom 79 (64%) had community-acquired and 44 (36%) had healthcare-associated UTIs. Community-acquired isolates were associated with acute uncomplicated UTIs (odds ratio [OR] 6.62, 95% confidence interval [CI] 1.83-36.5, P<0.001). Risk factors were recurrent UTI (OR 3.04, 95% CI 1.14-9.14, P=0.022) and female sex (OR 2.46, 95% CI 1.01-6.08). Community-acquired ESBL-producing E. coli urinary isolates showed high resistance rates to most of the currently used oral antimicrobial agents, including β-lactam antibiotics (amoxicillin-clavulanic acid, 69.6% resistance), quinolones (ciprofloxacin, 84.8% resistance; norfloxacin, 83.9% resistance), and trimethoprim-sulfamethoxazole (75.9% resistance), except for nitrofurantoin (15% resistance) and fosfomycin (0% resistance). Conclusion: UTI due to ESBL-producing E. coli are emerging, and also in a country with low antibiotic use. Because of increasing antibiotic resistance rates of E. coli to current standard therapy and because of the resistance patterns of ESBL-producing E. coli, guidelines for the management of UTIs must be revised. Fosfomycin or nitrofurantoin are recommended for the first-line empirical oral treatment of community-acquired uncomplicated UTI