Universality of Entanglement and Quantum Computation Complexity

We study the universality of scaling of entanglement in Shor's factoring algorithm and in adiabatic quantum algorithms across a quantum phase transition for both the NP-complete Exact Cover problem as well as the Grover's problem. The analytic result for Shor's algorithm shows a linear scaling of the entropy in terms of the number of qubits, therefore difficulting the possibility of an efficient classical simulation protocol. A similar result is obtained numerically for the quantum adiabatic evolution Exact Cover algorithm, which also shows universality of the quantum phase transition the system evolves nearby. On the other hand, entanglement in Grover's adiabatic algorithm remains a bounded quantity even at the critical point. A classification of scaling of entanglement appears as a natural grading of the computational complexity of simulating quantum phase transitions.Comment: 30 pages, 17 figures, accepted for publication in PR

Adiabatic quantum computation and quantum phase transitions

We analyze the ground state entanglement in a quantum adiabatic evolution algorithm designed to solve the NP-complete Exact Cover problem. The entropy of entanglement seems to obey linear and universal scaling at the point where the mass gap becomes small, suggesting that the system passes near a quantum phase transition. Such a large scaling of entanglement suggests that the effective connectivity of the system diverges as the number of qubits goes to infinity and that this algorithm cannot be efficiently simulated by classical means. On the other hand, entanglement in Grover's algorithm is bounded by a constant.Comment: 5 pages, 4 figures, accepted for publication in PR

Geometric entanglement from matrix product state representations

An efficient scheme to compute the geometric entanglement per lattice site for quantum many-body systems on a periodic finite-size chain is proposed in the context of a tensor network algorithm based on the matrix product state representations. It is systematically tested for three prototypical critical quantum spin chains, which belong to the same Ising universality class. The simulation results lend strong support to the previous claim [Q.-Q. Shi, R. Or\'{u}s, J. O. Fj{\ae}restad, and H.-Q. Zhou, New J. Phys \textbf{12}, 025008 (2010); J.-M. St\'{e}phan, G. Misguich, and F. Alet, Phys. Rev. B \textbf{82}, 180406R (2010)] that the leading finite-size correction to the geometric entanglement per lattice site is universal, with its remarkable connection to the celebrated Affleck-Ludwig boundary entropy corresponding to a conformally invariant boundary condition.Comment: 4+ pages, 3 figure

A numerical approach to analyze the performance of a PEF-Ohmic heating system in microbial inactivation of solid food

Pulsed Electric Fields (PEF) technology has been recently proposed as a new ohmic-heating system for the heat treatment of solid products in short periods (less than 1 min). However, similar to traditional ohmic heating, non-homogeneous distribution of temperature has been observed and cold points appeared in the interphase between the solid treated product and the electrodes, which can limit the technology for assuring food safety for treated solid products. In this investigation, a computational axisymmetric model of a lab-scale PEF system for a solid product (agar cylinder) was developed. This model was used to predict the temperature and the electric field distribution, treatment time, and the microbial inactivation (Salmonella Typhimurium 878) in the solid product after a PEF-ohmic treatment. Using a factorial analysis, a total of 8 process conditions with different settings of applied field strength levels (2.5–3.75 kV/cm), frequencies (100–200 Hz), and initial agar and electrode temperature (40–50°C) were simulated for the agar cylinder in order to identify the effect and optimal values of these parameters, which offer the most temperature homogeneity. The results showed that the initial temperature of the agar and the electrodes was of great importance in achieving the best temperature uniformity, limiting the occurrence of cold points, and therefore, improving the homogeneity in the level of inactivation of Salmonella Typhimurium 878 all over the agar cylinder. A treatment of 2.3 s would be enough at 3.75 kV/cm, 200 Hz with an initial temperature of 50°C of the agar and the electrodes, for a 5-Log10 reduction of Salmonella Typhimurium 878 in the whole product with a deviation of 9°C between the coldest and hottest point of the solid

Experiencia y resultados preliminares en el uso de cilindros intersomáticos para la artrodesis lumbar

El dolor lumbar crónico es una patología que puede llegar a ser incapacitante y en la que a menudo fracasan los tratamientos conservadores. Como alternativa entre las cirugías que pretenden atajar este problema mediante una artrodesis está la fusión intersomática con cilindros, que presenta algunas ventajas respecto a otras técnicas de fijación. Esta técnica ha sido introducida recientemente en nuestro país. Se presentan los primeros resultados obtenidos tras esta cirugía en los primeros 16 pacientes operados. Desde 1997 a diciembre de 2000 se han implantado 11 cilindros BAK y 5 LIFEC. Diez pacientes tenían un seguimiento mínimo de 1 año y éstos constituyen la serie evaluada. Siete pacientes (70%) no presentaban dolor. Cuatro pacientes (40%) se habían incorporado a sus trabajos respectivos. Seis pacientes (60%) no precisaban tratamiento médico. Los buenos resultados obtenidos hasta el momento nos invitan a pensar que esta técnica, de menor agresividad y que no cierra la puerta a otros tipos de instrumentación, es una opción válida para el tratamiento del dolor lumbar crónico.Chronic low back pain is a medical cause of disability in which conservative management is often not effective. As an alternative, interbody fusion with cylinders offers several advantages as compared to other surgical methods of fusion. This technique has been recently introduced in our Country. The preliminary results of 16 patients managed in our Department are shown. From 1997 to December 2000, eleven BAK devices and 5 LIFEC have been implanted. Ten patients had a minimum follow-up of 1 year and these constitute the series evaluated. Seven patients (70%) were free of pain. Four patients (40%) returned to their previous job. Six patients (60%) did not need medical treatment. The good results with this technique encourage us and suggest that these devices are a valid option for the management of chronic low back pain

Long-range vortex transfer in superconducting nanowires

Under high-enough values of perpendicularly-applied magnetic field and current, a type-II superconductor presents a finite resistance caused by the vortex motion driven by the Lorentz force. To recover the dissipation-free conduction state, strategies for minimizing vortex motion have been intensely studied in the last decades. However, the non-local vortex motion, arising in areas depleted of current, has been scarcely investigated despite its potential application for logic devices. Here, we propose a route to transfer vortices carried by non-local motion through long distances (up to 10 micrometers) in 50 nm-wide superconducting WC nanowires grown by Ga+ Focused Ion Beam Induced Deposition. A giant non-local electrical resistance of 36 Ω has been measured at 2 K in 3 μm-long nanowires, which is 40 times higher than signals reported for wider wires of other superconductors. This giant effect is accounted for by the existence of a strong edge confinement potential that hampers transversal vortex displacements, allowing the long-range coherent displacement of a single vortex row along the superconducting channel. Experimental results are in good agreement with numerical simulations of vortex dynamics based on the time-dependent Ginzburg-Landau equations. Our results pave the way for future developments on information technologies built upon single vortex manipulation in nano-superconductorsThis work was supported by the financial support from Spanish Ministry of Economy and Competitiveness through the projects MAT2015-69725-REDT, MAT2017-82970-C2-1-R and MAT2017-82970-C2-2-R, PIE201760E027, including FEDER funding, FIS2017-84330-R, MDM-2014-0377, FIS2016-80434-P and the Fundación Ramón Areces, EU ERC (Grant Agreement No. 679080), COST Grant No. CA16128 and STSM Grant from COST Action CA16218, and from regional Gobierno de Aragón (grants E13_17R and E28_17R) with European Social Fund (Construyendo Europa desde Aragón) and Comunidad de Madrid through project Nanofrontmag-CM (Grant No. S2013/MIT-2850

Case report : De novo pathogenic variant in WFS1 causes Wolfram-like syndrome debuting with congenital bilateral deafness

Background: Congenital deafness could be the first manifestation of a syndrome such as in Usher, Pendred, and Wolfram syndromes. Therefore, a genetic study is crucial in this deficiency to significantly improve its diagnostic efficiency, to predict the prognosis, to select the most adequate treatment required, and to anticipate the development of other associated clinical manifestations. Case presentation: We describe a young girl with bilateral congenital profound deafness, who initially received a single cochlear implant. The genetic study of her DNA using a custom-designed next-generation sequencing (NGS) panel detected a de novo pathogenic heterozygous variant in the WFS1 gene related to Wolfram-like syndrome, which is characterized by the presence of other symptoms such as optic atrophy. Due to this diagnosis, a second implant was placed after the optic atrophy onset. The speech audiometric results obtained with both implants indicate that this work successfully allows the patient to develop normal speech. Deterioration of the auditory nerves has not been observed. Conclusion: The next-generation sequencing technique allows a precise molecular diagnosis of diseases with high genetic heterogeneity, such as hereditary deafness, while this was the only symptom presented by the patient at the time of analysis. The NGS panel, in which genes responsible for both syndromic and non-syndromic hereditary deafness were included, was essential to reach the diagnosis in such a young patient. Early detection of the pathogenic variant in the WFS1 gene allowed us to anticipate the natural evolution of the disease and offer the most appropriate management to the patient

Evidence of galaxy interaction in the Narrow-line Seyfert 1 galaxy IRAS17020+4544 seen by NOEMA

The narrow-line Seyfert 1 galaxy IRAS17020+4544 is one of the few sources where both an X-ray ultra-fast outflow and a molecular outflow were observed to be consistent with energy conservation. However, IRAS17020+4544 is less massive and has a much more modest active galactic nucleus (AGN) luminosity than the other examples. Using recent CO(1-0) observations with the NOrthern Extended Millimeter Array (NOEMA), we characterised the molecular gas content of the host galaxy for the first time. We found that the molecular gas is distributed into an apparent central disc of 1.1x10^9 Msun, and a northern extension located up to 8 kpc from the centre with a molecular gas mass M_H2~10^8 Msun. The molecular gas mass and the CO dynamics in the northern extension reveal that IRAS 17020+4544 is not a standard spiral galaxy, instead it is interacting with a dwarf object corresponding to the northern extension. This interaction possibly triggers the high accretion rate onto the super massive black hole. Within the main galaxy, which hosts the AGN, a simple analytical model predicts that the molecular gas may lie in a ring, with less molecular gas in the nuclear region. Such distribution may be the result of the AGN activity which removes or photodissociates the molecular gas in the nuclear region (AGN feedback). Finally, we have detected a molecular outflow of mass M_H2=(0.7-1.2)x10^7 Msun in projection at the location of the northern galaxy, with a similar velocity to that of the massive outflow reported in previous millimeter data obtained by the Large Millimeter Telescope.Comment: Published in MNRAS, Volume 501, Issue 1, Pages 219-22

Comparison of GPS analysis strategies for high-accuracy vertical land motion

Tide gauges measure sea level changes relative to land. To separate absolute changes in sea level from vertical land movements tide gauges are often co-located with Continuous GPS (CGPS). In order to achieve an accuracy of better than 1 mm/yr, as required for sea level studies in the global change context, vertical land motion needs to be determined with the same accuracy. This is an ambitious goal for CGPS and needs a carefully designed analysis strategy. We have compared the independent results from six different analysis centres, using three different GPS processing softwares and a number of different analysis strategies. Based on the comparison, we discuss the achieved accuracy and the quality of the different strategies. The data analysed are from the CGPS network of the European Sea Level Service and cover the time window from the beginning of 2000 until the end of 2003. The comparison reveals large differences in the day-to-day variations of the coordinate time series and also in the seasonal cycle contained in these. The trends show systematic differences, depending on software and strategy used. To a large extent, the latter deviations can be explained by differences in the realisation of the reference frame, while some parts may be due to other, as yet, unidentified contributions. The results suggest that the reference frame and its relation to the center of mass of the Earth system may be the main limitation in achieving the accuracy goal for the secular velocity of vertical land motion.Peer ReviewedPostprint (published version