Experimental measurement-device-independent quantum digital signatures.

The development of quantum networks will be paramount towards practical and secure telecommunications. These networks will need to sign and distribute information between many parties with information-theoretic security, requiring both quantum digital signatures (QDS) and quantum key distribution (QKD). Here, we introduce and experimentally realise a quantum network architecture, where the nodes are fully connected using a minimum amount of physical links. The central node of the network can act either as a totally untrusted relay, connecting the end users via the recently introduced measurement-device-independent (MDI)-QKD, or as a trusted recipient directly communicating with the end users via QKD. Using this network, we perform a proof-of-principle demonstration of QDS mediated by MDI-QKD. For that, we devised an efficient protocol to distil multiple signatures from the same block of data, thus reducing the statistical fluctuations in the sample and greatly enhancing the final QDS rate in the finite-size scenario.

Ultra-fast quantum randomness generation by accelerated phase diffusion in a pulsed laser diode.

We demonstrate a high bit-rate quantum random number generator by interferometric detection of phase diffusion in a gain-switched DFB laser diode. Gain switching at few-GHz frequencies produces a train of bright pulses with nearly equal amplitudes and random phases. An unbalanced Mach-Zehnder interferometer is used to interfere subsequent pulses and thereby generate strong random-amplitude pulses, which are detected and digitized to produce a high-rate random bit string. Using established models of semiconductor laser field dynamics, we predict a regime of high visibility interference and nearly complete vacuum-fluctuation-induced phase diffusion between pulses. These are confirmed by measurement of pulse power statistics at the output of the interferometer. Using a 5.825 GHz excitation rate and 14-bit digitization, we observe 43 Gbps quantum randomness generation.

PP147. Prevalence of hypertensive syndromes according to pregnancy age.

INTRODUCTION: The decision of a woman to get pregnant at later age of her reproductive cycle has be a phenomenon around the world. Epidemiology data show frequent increase of clinical complications in direct proportion in advanced age motherhood, hypertensive disturbances being more prevalent. OBJECTIVES: Analyse the prevalence of hypertensive syndromes in pre-determined age groups at Hospital Guilherme Álvaro in Santos, São Paulo, Brazil showing the different segments in each one. METHODS: From data collected in the outpatient department of Hospital Guilherme Álvaro of High Risk Pre-natal between 04/06/2008 and 30/05/2011, a prevalence transversal study was carried out where data were obtained from 628 patients aged between 16 and 46years. Procedures of homogeny analysts were set out, always collecting data such as age and disorder for high risk gestation. According to age, patients were divided into groups: precocious (up to 19years old), middle age (between 20 and 34) and late pregnancies (over 35). RESULTS: In the precocious pregnancies, clinical illnesses/no hypertension (31%) were observed in first place, 25% (8) twin pregnancy in second place, 19% (6) showed hypertensive disturbances. Concerning pregnancies between 20 and 34years old, 36% (144 patients) showed hypertensive syndromes, 23% (92 patients) showed endocrine disturbances, 22% (90 patients) showed clinical illnesses/no hypertension, and 9% twin pregnancy. Regarding late pregnancies, the most frequent disturbance was isolated hypertensive syndromes: 44% (88 patients) in first place, only endocrine disturbances, 24% (47 patients) in second place followed by association between hypertensive syndromes and endocrinopathy with 13% (26 patients). CONCLUSION: About precocious pregnancies, greater prevalence showed clinical illnesses/no hypertension, whereas middle age and late pregnancies showed greater hypertensive syndrome prevalence, results, which are compatible with other studies, have been observed that due to advance of age, hypertensive syndromes are more frequent. For late pregnancies, the prevalence of clinical illnesses/no hypertension was a lower percentage regarding the other two groups: precocious pregnancies (31%=10 women), middle age pregnancies (22%=90 women), and late pregnancies (2%=7 women). Considering the fact that the occurrence of pregnancy is more and more late in life, it can be concluded that the professionals must be prepared to attend pregnancies on women with hypertensive disturbances and their eventual complications.

True random numbers from amplified quantum vacuum.

Random numbers are essential for applications ranging from secure communications to numerical simulation and quantitative finance. Algorithms can rapidly produce pseudo-random outcomes, series of numbers that mimic most properties of true random numbers while quantum random number generators (QRNGs) exploit intrinsic quantum randomness to produce true random numbers. Single-photon QRNGs are conceptually simple but produce few random bits per detection. In contrast, vacuum fluctuations are a vast resource for QRNGs: they are broad-band and thus can encode many random bits per second. Direct recording of vacuum fluctuations is possible, but requires shot-noise-limited detectors, at the cost of bandwidth. We demonstrate efficient conversion of vacuum fluctuations to true random bits using optical amplification of vacuum and interferometry. Using commercially-available optical components we demonstrate a QRNG at a bit rate of 1.11 Gbps. The proposed scheme has the potential to be extended to 10 Gbps and even up to 100 Gbps by taking advantage of high speed modulation sources and detectors for optical fiber telecommunication devices.