Two-axis-twisting spin squeezing by multi-pass quantum erasure

Many-body entangled states are key elements in quantum information science and quantum metrology. One important problem in establishing a high degree of many-body entanglement using optical techniques is the leakage of the system information via the light that creates such entanglement. We propose an all-optical interference-based approach to erase this information. Unwanted atom-light entanglement can be removed by destructive interference of three or more successive atom-light interactions, with only the desired effective atom-atom interaction left. This quantum erasure protocol allows implementation of Heisenberg-limited spin squeezing using coherent light and a cold or warm atomic ensemble. Calculations show that significant improvement in the squeezing exceeding 10 dB is obtained compared to previous methods, and substantial spin squeezing is attainable even under moderate experimental conditions. Our method enables the efficient creation of many-body entangled states with simple setups, and thus is promising for advancing technologies in quantum metrology and quantum information processing.Comment: 10 pages, 4 figures. We have improved the presentation and added a new section, in which we have generalized the scheme from a three-pass scheme to multi-pass schem

The effect of dietary antioxidants on hyperpigmented fillet spots of Atlantic salmon (Salmo salar L.)

Superficial discolored spots on Atlantic salmon fillets is a serious problem for the farming industry. Fillets with large dark stained spots are downgraded by the processing industry while smaller spots are removed, requiring extra labour. The main aim of the present study was to investigate the effect of diet on appearance, location and size of dark stained spots. The fish used were Atlantic salmon (Salmo salar L.) fed a standard commercial feed (Control) or the same feed added antioxidants (vitamin C, E and selenium) (Antioxidant). The experiment was carried out from 7th January to 13th March 2015. The results showed that the supplementation of antioxidants had no significantly effect on growth (average body weight 4 kg) or other biometric traits, but improved the fillet quality. Significantly lower occurrence of spots (31% vs. 45%), lower number of dark stained muscle segments (1.4 vs. 2.3), smaller fillet spot size (0.6 vs. 2.2 score) and lower fillet gaping score (0.8 vs. 1.0) were found of the Antioxidant group as compared to the Control group. Results showed that the melanin (40%) and a combination of melanin and scar (25%) were dominating the visual appearance of spots. Colorimetric analysis of the dark stained spots of the Antioxidant group revealed paler (higher L* value), less redness (lower a* value) and less yellowness (lower b* value) as compared to the Control group. Colorimetric characteristics of the dark spots were stable during one week of ice storage. Image analysis showed significantly higher lightness (higher L* value), less yellowness, larger area and wider width of myocommata of the Antioxidant group compared with the Control group. It is concluded that dietary supplementation of antioxidants reduced fillet gaping, occurrence of dark spots, spots size and number of dark stained muscle segments significantly.M-A

A fully nonlinear potential flow wave modelling procedure for simulations of offshore sea states with various wave breaking scenarios

An accurate representation of a given sea state is crucial for the study of hydrodynamic loads on offshore structures. It is straightforward to check the quality of the reproduced regular waves in a numerical wave tank (NWT). However, many more parameters need to be considered to ensure the quality of irregular waves. In this paper, a fully non-linear potential flow (FNPF) wave model is used to reproduce irregular sea states with different severity of wave breaking. The numerical model solves the velocity potential from the Laplace equation and the free surface boundary conditions using a finite difference method on a σ-coordinate grid. A comprehensive procedure is introduced to ensure the quality of the reproduced full-scale sea states. The effect of wave spectrum discretisation techniques and breaking wave algorithms are compared for an optimal performance. The evaluation of the simulation results takes into account the kurtosis and the wave crest distribution in addition to the wave spectra. The vertical arrangement of the σ-coordinate grid plays an important role in representing the dispersion relation and a grid optimisation method is explained. The current study provides a working procedure that reproduces high-fidelity irregular sea states with breaking waves in an efficient FNPF NWT.publishedVersio

When Intrusion Detection Meets Blockchain Technology: A Review

With the purpose of identifying cyber threats and possible incidents, intrusion detection systems (IDSs) are widely deployed in various computer networks. In order to enhance the detection capability of a single IDS, collaborative intrusion detection networks (or collaborative IDSs) have been developed, which allow IDS nodes to exchange data with each other. However, data and trust management still remain two challenges for current detection architectures, which may degrade the effectiveness of such detection systems. In recent years, blockchain technology has shown its adaptability in many fields, such as supply chain management, international payment, interbanking, and so on. As blockchain can protect the integrity of data storage and ensure process transparency, it has a potential to be applied to intrusion detection domain. Motivated by this, this paper provides a review regarding the intersection of IDSs and blockchains. In particular, we introduce the background of intrusion detection and blockchain, discuss the applicability of blockchain to intrusion detection, and identify open challenges in this direction