Stochastic antiresonance in qubit phase estimation with quantum thermal noise

We consider the fundamental quantum information processing task consisting in estimating the phase of a qubit. Following quantum measurement, the estimation performance is evaluated by the classical Fisher information which determines the best performance limiting any estimator and achievable by the maximum likelihood estimator. Estimation is analyzed in the presence of decoherence represented by a quantum thermal noise at arbitrary temperature. As the noise temperature is increased, we show the possibility of nontrivial behaviors of decoherence, with an estimation performance which does not necessarily degrade uniformly, but can experience nonmonotonic evolutions. Regimes are found where higher noise temperatures turn more favorable to estimation. Such behaviors are related to stochastic resonance or antiresonance effects, where noise reveals beneficial to information processing

Entropie de von Neumann et information de Holevo pour le signal quantique en présence de bruit

Entropie de von Neumann et information de Holevo pour le signal quantique en présence de bruit

Stochastic resonance with unital quantum noise

The fundamental quantum information processing task of estimating the phase of a qubit is considered. Following quantum measurement, the estimation efficiency is evaluated by the classical Fisher information which determines the best performance limiting any estimator and achievable by the maximum likelihood estimator. The estimation process is analyzed in the presence of decoherence represented by essential quantum noises that can affect the qubit and belonging to the broad class of unital quantum noises. Such a class especially contains the bit-flip, the phase-flip, the depolarizing noises, or the whole family of Pauli noises. As the level of noise is increased, we report the possibility of non-standard behaviors where the estimation efficiency does not necessarily deteriorate uniformly, but can experience non-monotonic variations. Regimes are found where higher noise levels prove more favorable to estimation. Such behaviors are related to stochastic resonance effects in signal estimation, shown here feasible for the first time with unital quantum noises. The results provide enhanced appreciation of quantum noise or decoherence, manifesting that it is not always detrimental for quantum information processing

Qubit state detection and enhancement by quantum thermal noise

The task fundamental to quantum communication and coding is considered which consists of detecting between two possible states of a noisy qubit, with a performance assessed by the overall probability of detection error. The detection process operates in the presence of decoherence represented by a quantum thermal noise at an arbitrary temperature. With uneven prior probabilities of the two states, as the noise temperature is increased, non-monotonic evolutions are reported for the performance, which does not uniformly degrade. Regimes are found where higher noise temperatures are more favourable to detection, with relation to stochastic resonance effects where noise reveals beneficial to information processing

L’intrication en imagerie quantique pour résister au bruit

L’intrication en imagerie quantique pour résister au bruit

Hopf solitons in the Nicole model

The Nicole model is a conformal field theory in a three-dimensional space. It has topological soliton solutions classified by the integer-valued Hopf charge, and all currently known solitons are axially symmetric. A volume-preserving flow is used to construct soliton solutions numerically for all Hopf charges from 1 to 8. It is found that the known axially symmetric solutions are unstable for Hopf charges greater than 2 and new lower energy solutions are obtained that include knots and links. A comparison with the Skyrme–Faddeev model suggests many universal features, though there are some differences in the link types obtained in the two theories

The Prosocial Framework: Theory, Practice and Applications Within Schools

Recent collaborations across psychological and evolutionary science have resulted in the emergence of an intervention programme for increasing the cohesion and effectiveness of human group processes. Prosocial (Atkins et al., 2019) combines Acceptance & Commitment Therapy (ACT; S. Hayes et al., 2012) and Multi-Level Selection Theory (Wilson & Sober, 1994) with Nobel Laureate Elinor Ostrom’s Core Design Principles (CDPs) for effective group-level processes (Ostrom, 2012, 2015). Ostrom’s work was ground-breaking but, being primarily descriptive in nature, did not provide a full account of the processes and procedures required to implement the CDPs. The current paper outlines the theoretical underpinnings of Prosocial and offers guidelines for its application within educational communities, providing specific examples of the wide array of ways in which the approach can be applied by professionals such as educational psychologists (EPs) to bring about positive change at the systemic level

A mathematical model to predict mean time to delivery following cervical ripening with dinoprostone vaginal insert

The main objective of our study was to analyze the mean time to delivery following cervical ripening with a 10 mg dinoprostone vaginal insert. We performed a retrospective observational study at the level III maternity ward of Angers university hospital. We included all women who had cervical ripening with dinoprostone between January 1, 2015 and September 30, 2016. Overall, 405 patients were included, and 59.3% (240/405) were nulliparous. The mean time to delivery was 20h39 min ± 10h49 min. 21% of deliveries (86/405) occurred between midnight and 6 h a.m., and the cesarean section rate was 33% (132/405). Multiple regression analysis showed that nulliparity, overweight (BMI ≥ 25), a closed cervix on initial examination and the absence of premature rupture of membranes (PRM) all significantly increased the mean time to delivery. We developed a mathematical model integrating the aforementioned factors and their impact to help predict the mean time to delivery following cervical ripening with dinoprostone vaginal insert: Y = 961.188-80.346 × parity + 21.437 × BMI-165.263 × cervical dilation-241.759 × PRM. This equation allows obstetricians to calculate a personalized time to delivery for each patient, allowing a precise scheduling of dinoprostone insert placement, and thus improving the organization in busy maternity wards

Enhancing qubit information with quantum thermal noise

Informational quantities characterizing the qubit are analyzed in the presence of quantum thermal noise modeling the decoherence process due to interaction with the environment represented as a heat bath at arbitrary temperature. Nontrivial regimes of variation are reported for the informational quantities, which do not necessarily degrade monotonically as the temperature of the thermal noise increases, but on the contrary can experience nonmonotonic variations where higher noise temperatures can prove more favorable. Such effects show that increased quantum decoherence does not necessarily entail poorer informational performance, and they are related to stochastic resonance or noise-enhanced efficiency in information processing

Electrohydraulic Forming of Light Weight Automotive Panels

This paper describes the results of development of the electrohydraulic forming (EHF) process as a near-net shape automotive panel manufacturing technology. EHF is an electro-dynamic process based upon high-voltage discharge of capacitors between two electrodes positioned in a fluid-filled chamber. This process is extremely fast, uses lowercost single-sided tooling, and potentially derives significantly increased formability from many sheet metal materials due to the elevated strain rate. Major results obtained during this study include: developing numerical model of the EHF; demonstrating increased formability for high-strength materials and other technical benefits of using EHF; developing the electrode design suitable for high volume production conditions; understanding the limitations on loads on the die in pulsed forming conditions; developing an automated fully computer controlled and robust EHF cell; demonstration of electrohydraulic springback calibration and electrohydraulic trimming of stamped panels; full scale demonstration of a hybrid conventional and EHF forming process for automotive dash panel