Dynamic nuclear polarization at high magnetic fields in liquids

High field dynamic nuclear polarization spectrometer for liquid samples have been constructed. ► The field dependence of the Overhauser DNP efficiency has been measured for the first time up to 9.2 T. ► High DNP enhancements for liquid samples have been observed at high magnetic fields. ► The enhancements have been compared with results from NMRD, MD and theoretical models. ► Coherent and relaxation effects within fast magnetic field changes have been analyzed

A high-fidelity noiseless amplifier for quantum light states

Noise is the price to pay when trying to clone or amplify arbitrary quantum states. The quantum noise associated to linear phase-insensitive amplifiers can only be avoided by relaxing the requirement of a deterministic operation. Here we present the experimental realization of a probabilistic noiseless linear amplifier that is able to amplify coherent states at the highest level of effective gain and final state fidelity ever reached. Based on a sequence of photon addition and subtraction, and characterized by a significant amplification and low distortions, this high-fidelity amplification scheme may become an essential tool for quantum communications and metrology, by enhancing the discrimination between partially overlapping quantum states or by recovering the information transmitted over lossy channels.Comment: 5 pages, 4 figure

Effects of parity order and reproductive management on the efficiency of rabbit productive systems.

The aim of this work was to study the effect of parity order and reproductive management systems on rabbit production performance. A total of 73 rabbit does (I group) were submitted to a 35-day intensive rhythm [artificial insemination (AI) on day 4 post-partum (pp) and weaning at 25 days of lactation], and 108 rabbit does (SI group) were submitted to a 42-day semi-intensive rhythm (AI on day 11 pp and weaning at 35 days of lactation) during 9 months. Primiparous does had the lowest live body weight at parturition (P < 0.0001) and at 21 days of lactation (P < 0.0001). They also had lower milk production (P < 0.0001) than does with later parities. I group animals needed a higher number of AI than SI group to become pregnant (1.70 ± 0.03 vs. 1.39 ± 0.03; P < 0.0001: especially after the third). Prolificacy was not affected by the management system. Parturition interval (PI) was longer than expected in both groups [56.0 ± 1.4 and 50.9 ± 1.38 days in I and SI groups, respectively (P < 0.05)]. Mean productivity, estimated as number of weaned rabbits per female and year, was 12 kits higher in rabbit does of the SI group (P < 0.05). From the third parturition onward, an increase in live body weight of kits at different ages was observed. At 21 (P < 0.05) and 25 days of age (P < 0.01), kits from the I group rabbit does weighed more than those from the SI group; however, the latter showed a higher weight at 35 (P < 0.05) and 60 days of age (P < 0.05). Rabbit does with two or three parturitions had higher litter size at 21 and 25 days of age (P < 0.0001 and P < 0.001, respectively). Kit mortality between 21 and 25 days of age and between 35 and 60 days of age was not affected by treatments but was higher in the I group between 25 and 35 days (18.2 vs. 5.03% in the I and SI groups, respectively; P < 0.0001) and as age of does increased (P < 0.05). In light of these results, we could conclude that long term doe reproductive performance is negatively affected and litter viability decreased when using intensive compared to a semi-intensive reproductive management

Demonstrating various quantum effects with two entangled laser beams

We report on the preparation of entangled two mode squeezed states of yet unseen quality. Based on a measurement of the covariance matrix we found a violation of the Reid and Drummond EPR-criterion at a value of only 0.36\pm0.03 compared to the threshold of 1. Furthermore, quantum state tomography was used to extract a single photon Fock state solely based on homodyne detection, demonstrating the strong quantum features of this pair of laser-beams. The probability for a single photon in this ensemble measurement exceeded 2/3

Laser hardening of steel sintered parts

The possibility of applying rapid and localized laser hardening to near-net shape parts, like the ones deriving from powder metallurgy (P/M) is investigated, demonstrating that even low alloyed steels (Fe + 2% Cu + 0,7% C) can be successfully heat treated with minimal or no dimensional variations. Laser hardening conditions have been selected on the basis of the results of the previous research, carried out by means of an Nd-YAG high power system [1]. To avoid some carbon loss, observed on previous activities, the samples have been protected by neutral atmosphere. The microstructural features of the laser hardened steels have been analyzed by optical microscopy, whereas the surface micro-geometry has been characterized by scanning electron microscope. Hardened depth (HD), hardened width (HW) and hardened area (HA) have been measured as well. As expected, the micro-hardness profiles present a sharp drop at low distance from the hardened surface. The typical splitting between hardened zone and heat-Affected zone (HAZ), well known from laser hardened fully dense steels, has been observed also on low-Alloy sintered steels. The use of a protective atmosphere has been helpful to control surface decarburization and to prevent oxidation. The research confirm that Laser transformation Hardening (LTH) is a suitable hardening process of P/M components, through the action of a scanning laser beam. The short heating time and the modest volume fraction structurally modified can contribute to avoid part distortion, in comparison with other hardening methods

Enhancement of Rydberg-mediated single-photon nonlinearities by electrically tuned Förster resonances

We demonstrate experimentally that Stark-tuned Förster resonances can be used to substantially increase the interaction between individual photons mediated by Rydberg interaction inside an optical medium. This technique is employed to boost the gain of a Rydberg-mediated single-photon transistor and to enhance the non-destructive detection of single Rydberg atoms. Furthermore, our all-optical detection scheme enables high-resolution spectroscopy of two-state Förster resonances, revealing the fine structure splitting of high-n Rydberg states and the non-degeneracy of Rydberg Zeeman substates in finite fields. We show that the ∣50S1/2,48S1/2⟩↔∣49P1/2,48P1/2⟩ pair state resonance in 87Rb enables simultaneously a transistor gain G>100 and all-optical detection fidelity of single Rydberg atoms F>0.8. We demonstrate for the first time the coherent operation of the Rydberg transistor with G>2 by reading out the gate photon after scattering source photons. Comparison of the observed readout efficiency to a theoretical model for the projection of the stored spin wave yields excellent agreement and thus successfully identifies the main decoherence mechanism of the Rydberg transistor

Experimental demonstration of bosonic commutation relation via superpositions of quantum operations on thermal light fields

We present the experimental realization of a scheme, based on single-photon interference, for implementing superpositions of distinct quantum operations. Its application to a thermal light field (a well-categorized classical entity) illustrates quantum superposition from a new standpoint and provides a direct and quantitative verification of the bosonic commutation relation between creation and annihilation operators. By shifting the focus towards operator superpositions, this result opens interesting alternative perspectives for manipulating quantum states.Comment: 4 pages, 3 figures, to appear in Physical Review Letter