Dynamics of magnetization at infinite temperature in a Heisenberg spin chain

Understanding universal aspects of quantum dynamics is an unresolved problem in statistical mechanics. In particular, the spin dynamics of the one-dimensional Heisenberg model were conjectured as to belong to the Kardar-Parisi-Zhang (KPZ) universality class based on the scaling of the infinite-temperature spin-spin correlation function. In a chain of 46 superconducting qubits, we studied the probability distribution of the magnetization transferred across the chain's center, [Formula: see text]. The first two moments of [Formula: see text] show superdiffusive behavior, a hallmark of KPZ universality. However, the third and fourth moments ruled out the KPZ conjecture and allow for evaluating other theories. Our results highlight the importance of studying higher moments in determining dynamic universality classes and provide insights into universal behavior in quantum systems.

Stable quantum-correlated many-body states through engineered dissipation

Engineered dissipative reservoirs have the potential to steer many-body quantum systems toward correlated steady states useful for quantum simulation of high-temperature superconductivity or quantum magnetism. Using up to 49 superconducting qubits, we prepared low-energy states of the transverse-field Ising model through coupling to dissipative auxiliary qubits. In one dimension, we observed long-range quantum correlations and a ground-state fidelity of 0.86 for 18 qubits at the critical point. In two dimensions, we found mutual information that extends beyond nearest neighbors. Lastly, by coupling the system to auxiliaries emulating reservoirs with different chemical potentials, we explored transport in the quantum Heisenberg model. Our results establish engineered dissipation as a scalable alternative to unitary evolution for preparing entangled many-body states on noisy quantum processors.

Optimizing quantum gates towards the scale of logical qubits

A foundational assumption of quantum error correction theory is that quantum gates can be scaled to large processors without exceeding the error-threshold for fault tolerance. Two major challenges that could become fundamental roadblocks are manufacturing high-performance quantum hardware and engineering a control system that can reach its performance limits. The control challenge of scaling quantum gates from small to large processors without degrading performance often maps to non-convex, high-constraint, and time-dynamic control optimization over an exponentially expanding configuration space. Here we report on a control optimization strategy that can scalably overcome the complexity of such problems. We demonstrate it by choreographing the frequency trajectories of 68 frequency-tunable superconducting qubits to execute single- and two-qubit gates while mitigating computational errors. When combined with a comprehensive model of physical errors across our processor, the strategy suppresses physical error rates by ~3.7× compared with the case of no optimization. Furthermore, it is projected to achieve a similar performance advantage on a distance-23 surface code logical qubit with 1057 physical qubits. Our control optimization strategy solves a generic scaling challenge in a way that can be adapted to a variety of quantum operations, algorithms, and computing architectures.

Measurement-induced entanglement and teleportation on a noisy quantum processor

Measurement has a special role in quantum theory1: by collapsing the wavefunction, it can enable phenomena such as teleportation2 and thereby alter the 'arrow of time' that constrains unitary evolution. When integrated in many-body dynamics, measurements can lead to emergent patterns of quantum information in space-time3-10 that go beyond the established paradigms for characterizing phases, either in or out of equilibrium11-13. For present-day noisy intermediate-scale quantum (NISQ) processors14, the experimental realization of such physics can be problematic because of hardware limitations and the stochastic nature of quantum measurement. Here we address these experimental challenges and study measurement-induced quantum information phases on up to 70 superconducting qubits. By leveraging the interchangeability of space and time, we use a duality mapping9,15-17 to avoid mid-circuit measurement and access different manifestations of the underlying phases, from entanglement scaling3,4 to measurement-induced teleportation18. We obtain finite-sized signatures of a phase transition with a decoding protocol that correlates the experimental measurement with classical simulation data. The phases display remarkably different sensitivity to noise, and we use this disparity to turn an inherent hardware limitation into a useful diagnostic. Our work demonstrates an approach to realizing measurement-induced physics at scales that are at the limits of current NISQ processors.

Non-Abelian braiding of graph vertices in a superconducting processor

Indistinguishability of particles is a fundamental principle of quantum mechanics¹. For all elementary and quasiparticles observed to date-including fermions, bosons and Abelian anyons-this principle guarantees that the braiding of identical particles leaves the system unchanged^2,3. However, in two spatial dimensions, an intriguing possibility exists: braiding of non-Abelian anyons causes rotations in a space of topologically degenerate wavefunctions^4-8. Hence, it can change the observables of the system without violating the principle of indistinguishability. Despite the well-developed mathematical description of non-Abelian anyons and numerous theoretical proposals^9-22, the experimental observation of their exchange statistics has remained elusive for decades. Controllable many-body quantum states generated on quantum processors offer another path for exploring these fundamental phenomena. Whereas efforts on conventional solid-state platforms typically involve Hamiltonian dynamics of quasiparticles, superconducting quantum processors allow for directly manipulating the many-body wavefunction by means of unitary gates. Building on predictions that stabilizer codes can host projective non-Abelian Ising anyons^9,10, we implement a generalized stabilizer code and unitary protocol²³ to create and braid them. This allows us to experimentally verify the fusion rules of the anyons and braid them to realize their statistics. We then study the prospect of using the anyons for quantum computation and use braiding to create an entangled state of anyons encoding three logical qubits. Our work provides new insights about non-Abelian braiding and, through the future inclusion of error correction to achieve topological protection, could open a path towards fault-tolerant quantum computing.

Formation of robust bound states of interacting microwave photons

Systems of correlated particles appear in many fields of modern science and represent some of the most intractable computational problems in nature. The computational challenge in these systems arises when interactions become comparable to other energy scales, which makes the state of each particle depend on all other particles1. The lack of general solutions for the three-body problem and acceptable theory for strongly correlated electrons shows that our understanding of correlated systems fades when the particle number or the interaction strength increases. One of the hallmarks of interacting systems is the formation of multiparticle bound states2-9. Here we develop a high-fidelity parameterizable fSim gate and implement the periodic quantum circuit of the spin-½ XXZ model in a ring of 24 superconducting qubits. We study the propagation of these excitations and observe their bound nature for up to five photons. We devise a phase-sensitive method for constructing the few-body spectrum of the bound states and extract their pseudo-charge by introducing a synthetic flux. By introducing interactions between the ring and additional qubits, we observe an unexpected resilience of the bound states to integrability breaking. This finding goes against the idea that bound states in non-integrable systems are unstable when their energies overlap with the continuum spectrum. Our work provides experimental evidence for bound states of interacting photons and discovers their stability beyond the integrability limit.

Noise-resilient edge modes on a chain of superconducting qubits

Inherent symmetry of a quantum system may protect its otherwise fragile states. Leveraging such protection requires testing its robustness against uncontrolled environmental interactions. Using 47 superconducting qubits, we implement the one-dimensional kicked Ising model, which exhibits nonlocal Majorana edge modes (MEMs) with ℤ 2 parity symmetry. We find that any multiqubit Pauli operator overlapping with the MEMs exhibits a uniform late-time decay rate comparable to single-qubit relaxation rates, irrespective of its size or composition. This characteristic allows us to accurately reconstruct the exponentially localized spatial profiles of the MEMs. Furthermore, the MEMs are found to be resilient against certain symmetry-breaking noise owing to a prethermalization mechanism. Our work elucidates the complex interplay between noise and symmetry-protected edge modes in a solid-state environment.

[Gestational diabetes mellitus : prelude of risks not to be misunderstood]

Gestational diabetes mellitus is a common complication in pregnant women. It is diagnosed between the 24th and 28th last menstrual period thanks to an oral glucose tolerance test with 75 g of glucose. Although blood glucose levels usually return to normal after childbirth, it can lead to some medium- and long-term complications, including cardiovascular, metabolic and renal complications. Early detection of various risk factors related to these complications would avoid some negative consequences for women with background of gestational diabetes.

Realizing topologically ordered states on a quantum processor

[Figure: see text].

Time-Crystalline Eigenstate Order on a Quantum Processor

Quantum many-body systems display rich phase structure in their low-temperature equilibrium states¹. However, much of nature is not in thermal equilibrium. Remarkably, it was recently predicted that out-of-equilibrium systems can exhibit novel dynamical phases^2–8 that may otherwise be forbidden by equilibrium thermodynamics, a paradigmatic example being the discrete time crystal (DTC)^7,9–15. Concretely, dynamical phases can be defined in periodically driven many-body-localized (MBL) systems via the concept of eigenstate order^7,16,17. In eigenstate-ordered MBL phases, the entire many-body spectrum exhibits quantum correlations and long-range order, with characteristic signatures in late-time dynamics from all initial states. It is, however, challenging to experimentally distinguish such stable phases from transient phenomena, or from regimes in which the dynamics of a few select states can mask typical behaviour. Here we implement tunable controlled-phase (CPHASE) gates on an array of superconducting qubits to experimentally observe an MBL-DTC and demonstrate its characteristic spatiotemporal response for generic initial states^7,9,10. Our work employs a time-reversal protocol to quantify the impact of external decoherence, and leverages quantum typicality to circumvent the exponential cost of densely sampling the eigenspectrum. Furthermore, we locate the phase transition out of the DTC with an experimental finite-size analysis. These results establish a scalable approach to studying non-equilibrium phases of matter on quantum processors.

A study establishes a scalable approach to engineer and characterize a many-body-localized discrete time crystal phase on a superconducting quantum processor.

Information scrambling in quantum circuits

[Figure: see text].

Removing leakage-induced correlated errors in superconducting quantum error correction

Quantum computing can become scalable through error correction, but logical error rates only decrease with system size when physical errors are sufficiently uncorrelated. During computation, unused high energy levels of the qubits can become excited, creating leakage states that are long-lived and mobile. Particularly for superconducting transmon qubits, this leakage opens a path to errors that are correlated in space and time. Here, we report a reset protocol that returns a qubit to the ground state from all relevant higher level states. We test its performance with the bit-flip stabilizer code, a simplified version of the surface code for quantum error correction. We investigate the accumulation and dynamics of leakage during error correction. Using this protocol, we find lower rates of logical errors and an improved scaling and stability of error suppression with increasing qubit number. This demonstration provides a key step on the path towards scalable quantum computing.

Sport-specific differences in dynamic visual acuity and gaze stabilization in division-I collegiate athletes

BACKGROUND:

The vestibular-ocular reflex (VOR) integrates the vestibular and ocular systems to maintain gaze during head motion. This reflex is often negatively affected following sport-related concussion. Objective measures of gaze stability, a function mediated by the VOR, such as the computerized dynamic visual acuity test (DVAT) and gaze stabilization test (GST), may have utility in concussion management. However, normative data specific to sport, sex, or concussion history have not been established in collegiate athletes.

OBJECTIVE:

The objective of this study was to establish normative values for the DVAT and GST in collegiate athletes and explore the effect of sport, sex, and concussion history on VOR assessments.

METHODS:

The DVAT and GST were completed by 124 collegiate athletes (72 male, 52 female, mean±SD, age: 19.71±1.74 years, height: 173.99±13.97 cm, weight: 80.06±26.52 kg) recruited from Division-I athletic teams (football, soccer and cheerleading). The DVAT and GST were performed in the rightward and leftward directions during a single session in a standardized environment. Normative values for DVAT and GST measures were expressed as percentiles. Non-parametric statistics were used to compare differences between groups based on sex, sport, and concussion history. Alpha was set a-priori at 0.05.

RESULTS:

Overall, the median LogMAR unit for 124 athletes completing the DVAT was 0 (IQR = 0.17) for both leftward and rightward. The median velocities achieved on the GST were 145 °/sec and 150 °/sec (IQR = 45 and 40) for the leftward and rightward directions respectively. Significant differences were observed between sports (p = 0.001–0.17) for the GST with cheerleading demonstrating higher velocities than the other sports. However, no significant differences were identified based on sex (p≥0.09) or history of concussion (p≥0.15).

CONCLUSIONS:

Normative estimates for the DVAT and GST may assist in the clinical interpretation of outcomes when used in post-concussion evaluation for collegiate athletes. Although sex and previous concussion history had no effect on the DVAT or GST, performance on these measures may be influenced by type of sport. Sport-related differences in the GST may reflect VOR adaptations based on individual sport-specific demands.

Demonstrating a Continuous Set of Two-Qubit Gates for Near-Term Quantum Algorithms

Quantum algorithms offer a dramatic speedup for computational problems in material science and chemistry. However, any near-term realizations of these algorithms will need to be optimized to fit within the finite resources offered by existing noisy hardware. Here, taking advantage of the adjustable coupling of gmon qubits, we demonstrate a continuous two-qubit gate set that can provide a threefold reduction in circuit depth as compared to a standard decomposition. We implement two gate families: an imaginary swap-like (iSWAP-like) gate to attain an arbitrary swap angle, θ, and a controlled-phase gate that generates an arbitrary conditional phase, ϕ. Using one of each of these gates, we can perform an arbitrary two-qubit gate within the excitation-preserving subspace allowing for a complete implementation of the so-called Fermionic simulation (fSim) gate set. We benchmark the fidelity of the iSWAP-like and controlled-phase gate families as well as 525 other fSim gates spread evenly across the entire fSim(θ,ϕ) parameter space, achieving a purity-limited average two-qubit Pauli error of 3.8×10^{-3} per fSim gate.

Hartree-Fock on a superconducting qubit quantum computer

The simulation of fermionic systems is among the most anticipated applications of quantum computing. We performed several quantum simulations of chemistry with up to one dozen qubits, including modeling the isomerization mechanism of diazene. We also demonstrated error-mitigation strategies based on N-representability that dramatically improve the effective fidelity of our experiments. Our parameterized ansatz circuits realized the Givens rotation approach to noninteracting fermion evolution, which we variationally optimized to prepare the Hartree-Fock wave function. This ubiquitous algorithmic primitive is classically tractable to simulate yet still generates highly entangled states over the computational basis, which allowed us to assess the performance of our hardware and establish a foundation for scaling up correlated quantum chemistry simulations.

Process Simulation-Based Design, Mold Construction and Mechanical Performance Evaluation of an Insert-Injection Molded Thermoplastic Polyurethane Part

This paper presents a case study of simulation-based design and experimental validation of the insert-injection molding process of a complex polyurethane part. The part under consideration is a dowel holder which is a machine element used in the concrete railway sleepers production. A simulation study was carried out to define the relevant mold design options and optimal molding parameters as well as to evaluate their influence on the part's quality indexes. Simulation was performed using the software Moldex3D. The mold was constructed according to the optimization analysis and a batch of pieces was manufactured under the optimized conditions. A mechanical testing experiment – representing the actual service loading conditions – was designed and performed to validate the mold and process designs and the part performance. Simulation and statistical analysis results allowed determining those conditions that lead to a better assembly between the part and the metallic insert and to its structural integrity. The mechanical performance evaluation demonstrated that the part meets all its functional and structural requirements, validating simulation predictions.

A-34 Sex and Sport Differences in Baseline Neurocognitive Performance in Division-I Collegiate Athletes using the NIH Toolbox® Cognition Battery

Objective

Understanding sex and sport-related differences in baseline neurocognitive scores may aid in interpreting post-injury performance. Sex and sport-related differences in neurocognitive performance for collegiate athletes have not been examined on the NIH Toolbox® Cognition Battery (NIHTB-CB). Therefore, this study sought to determine if baseline scores on the NIHTB-CB differ between sex or sport in collegiate athletes. It was hypothesized that sex, but not sport-related differences would exist in CB baseline performance.

Method

107 Division-I athletes (47 females, 60 males) that participated in soccer (n = 45), football (n = 30), or cheerleading (n = 32) volunteered to participate. Participants completed tablet-based NIHTB-CB assessments including the Flanker Inhibitory Control & Attention (FICA), Dimensional Change Card Sort (DCCS), Picture Sequence Memory (PSM), and Pattern Comparison Processing Speed (PCPS) tests. These assessments measured visual attention, cognitive flexibility, memory recall, and processing speed, respectively. Fully corrected t-scores were used for analyses. Parametric and non-parametric tests compared scores based on sex and sport.

Results

Females demonstrated greater performance on the PCPS (Females: 64.72 ± 9.84, Males: 61.08 ± 8.85; p = 0.006). Males exhibited better performance on the FICA (Females: 45.72 ± 10.12, Males: 51.03 ± 10.70; p = 0.009). After controlling for sex, a significant difference across sports was identified in the FICA (p = 0.007) with cheerleading (43.81 ± 9.28) exhibiting poorer performance than football (54.33 ± 10.44; p = 0.002) and soccer (48.42 ± 10.28; p = 0.047). No sex or sport differences were identified for the DCCS or PSM.

Conclusions

Baseline differences in neurocognitive performance exist on the NIHTB-CB based on sex and sport suggesting these variables be taken into consideration when interpreting post-concussion scores in collegiate athletes.

AB0994 NEW ALTERNATIVE IN THE TREATMENT OF PATIENT WITH MUTATION OF GEN LACC1

Background:

Few patients have been described in the literature with mutations in the Lacasa Domain containing one (LACC1) gene. Its clinical presentation usually associates sustained systemic inflammation associated with chronic polyarticular erosive arthritis. Until now, there have been multiple treatments described to try to control the disease, however, they are generally unsuccessful in the long term.

Objectives:

Describe the clinical course of a patient as well as the different treatments used

Methods:

Clinical chart review

Results:

Female 18-year-old born from a consanguineous Moroccan couple. Mother, brother and sister with similar conditions. She started at 3 years with fever, anemia, intense elevation of acute phase reactants and symmetric polyarthritis (knees, elbows, carps, shoulders, hands and ankles). Subsequent whole exome sequencing identified c.128_129delGT mutation in the LACC1/FAMIN gene. During the course of her illness, she has received treatment with oral, intravenous and infiltrated corticosteroid, methotrexate and etanercept, without getting adequate control of the disease. In 2016, she started treatment with tocilizumab (8 mg / kg every two weeks), obtaining an acceptable control of the disease (requiring periodic infiltrations every 2-3 months due to persistent arthritis). Nonetheless, in April 2019, she consulted for clinical worsening of the arthritis and laboratory test (C reactive protein 99.7 mg / L, erythrosedimentation rate 53 mm / h, leukocytes 13,500/µL and neutrophils 10,930/µL). At that time, she discontinued therapy with tocilizumab and started tofacitinib 5 mg every 12 hours with good evolution. Since its introduction, it has not required joint infiltration again and the inflammatory parameters (persistently elevated previously) have normalized.

Conclusion:

The jak kinasa inhibitors may be a treatment option in those patients with bad response to conventional therapy.

References:

[1]Rabionet R, Remesal A, Mensa-Vilaró A, Murías S, Alcobendas R, González-Roca E, Ruiz-Ortiz E, Antón J, Iglesias E, Modesto C, Comas D, Puig A, Drechsel O, Ossowski S, Yagüe J, Merino R, Estivill X, Arostegui JI. Biallelic loss-of-function LACC1/FAMIN Mutations Presenting as Rheumatoid Factor-Negative Polyarticular Juvenile Idiopathic Arthritis. Sci Rep. 2019 Mar 14;9(1):4579

Disclosure of Interests:

None declared

Differences in head accelerations and physiological demand between live and simulated professional horse racing

The purpose of this study was to determine if there are differences in mechanical and physiological demand between live and simulated racing. Fifteen male professional jockeys (31.8±9.5 years, 160.78±7.62 cm, 51.2±1.5 kg) were instrumented with inertial measurement units (IMUs) placed on their helmets to measure mechanical stress and a heart rate (HR) monitor. Head accelerations and HR were measured during a live race (between 5.5 and 6.5 furlongs) and a simulated race (equivalent of 6.5 furlongs or 1.5 min) on a race horse simulator. Paired t-tests were used to determine if there were differences between the two racing conditions for each dependent variable. Alpha level was set at P<0.05. Average HR and peak HR were significantly higher during live than simulated racing. The peak resultant linear acceleration, the average resultant linear acceleration, and the peak resultant rotational velocity were significantly higher in live racing than simulated racing. There were no significant differences in average resultant rotational velocity. Simulated racing trials had consistently lower values of head accelerations compared to live racing trials. These results may provide justification for the use of a race horse simulator as a tool capable of use in rehabilitating and returning jockeys to ride following injury as the accelerations and velocities measured on simulated racing trials were lower, suggesting a safer sports-specific exercise, while still approaching the physiological demands of live racing.

The Relation Between Cognitive Performance and Symptom Factors Following Concussion

Purpose

The purpose of this study was to explore if symptom factors are related to cognitive outcomes. Prior studies have examined the relationship of individual symptoms to cognition. However, the relation between empirically-derived symptom factors and cognitive outcomes has yet to be explored.

Methods

Data were extracted via retrospective chart review of 691 patients (aged 10–24, mean: 14.99±2.63). Participants completed ImPACT and the PCSS within 14 days of injury (mean: 9.27±3.37). Predictors were PCSS factor scores of Cognitive-Fatigue-Migraine (CFM), Affective (AFF), Somatic (SOM), and Sleep (SLP) (Kontos et al., 2012). Outcomes examined were ImPACT composite scores. Univariate analyses were performed and values with p < 0.10 were entered into stepwise linear regression (LR) models. Retained predictors in each LR model had p values <.05.

Results

Verbal memory was predicted by CFM, SOM, age, and gender. Visual memory was predicted by CFM and SOM. Visual motor speed was predicted by age, gender, CFM, SOM, and AFF. Reaction time was best predicted by SOM, CFM, and age. The variance explained was fairly small (0.08 to 0.21). SLP was not a significant predictor in any LR.

Conclusion

CFM and SOM factors were most predictive of lower cognitive performance, similar to prior studies linking dizziness to longer recovery and post-traumatic migraine to worse cognitive performance. These findings underscore the clinical importance of diverse symptom assessment and injury education. Higher CFM and SOM scores may also serve as proxy for injury severity, which we would expect to be associated with worse cognitive performance.

Identical and Nonidentical Twins: Risk and Factors Involved in Development of Islet Autoimmunity and Type 1 Diabetes

OBJECTIVE

There are variable reports of risk of concordance for progression to islet autoantibodies and type 1 diabetes in identical twins after one twin is diagnosed. We examined development of positive autoantibodies and type 1 diabetes and the effects of genetic factors and common environment on autoantibody positivity in identical twins, nonidentical twins, and full siblings.

RESEARCH DESIGN AND METHODS

Subjects from the TrialNet Pathway to Prevention Study (N = 48,026) were screened from 2004 to 2015 for islet autoantibodies (GAD antibody [GADA], insulinoma-associated antigen 2 [IA-2A], and autoantibodies against insulin [IAA]). Of these subjects, 17,226 (157 identical twins, 283 nonidentical twins, and 16,786 full siblings) were followed for autoantibody positivity or type 1 diabetes for a median of 2.1 years.

RESULTS

At screening, identical twins were more likely to have positive GADA, IA-2A, and IAA than nonidentical twins or full siblings (all P < 0.0001). Younger age, male sex, and genetic factors were significant factors for expression of IA-2A, IAA, one or more positive autoantibodies, and two or more positive autoantibodies (all P ≤ 0.03). Initially autoantibody-positive identical twins had a 69% risk of diabetes by 3 years compared with 1.5% for initially autoantibody-negative identical twins. In nonidentical twins, type 1 diabetes risk by 3 years was 72% for initially multiple autoantibody-positive, 13% for single autoantibody-positive, and 0% for initially autoantibody-negative nonidentical twins. Full siblings had a 3-year type 1 diabetes risk of 47% for multiple autoantibody-positive, 12% for single autoantibody-positive, and 0.5% for initially autoantibody-negative subjects.

CONCLUSIONS

Risk of type 1 diabetes at 3 years is high for initially multiple and single autoantibody-positive identical twins and multiple autoantibody-positive nonidentical twins. Genetic predisposition, age, and male sex are significant risk factors for development of positive autoantibodies in twins.

Fluctuations of Energy-Relaxation Times in Superconducting Qubits

Superconducting qubits are an attractive platform for quantum computing since they have demonstrated high-fidelity quantum gates and extensibility to modest system sizes. Nonetheless, an outstanding challenge is stabilizing their energy-relaxation times, which can fluctuate unpredictably in frequency and time. Here, we use qubits as spectral and temporal probes of individual two-level-system defects to provide direct evidence that they are responsible for the largest fluctuations. This research lays the foundation for stabilizing qubit performance through calibration, design, and fabrication.

Nanoparticles confined to a spherical surface in the presence of an external field: Interaction forces and induced microstructure

The structural response of a set of charged nanoparticles confined to move on a spherical surface under the influence of an external field is studied by Brownian Dynamics (BD) simulations and by an integral equation approach (IEA). Considering an identical nanoparticle as the source of the external field, we analyze the force exerted by the N confined particles on the external one, as well as the corresponding potential energy, focusing on their dependence on the distance of the external particle to the center of the sphere r₀. The connection of the force and potential to the equilibrium local distribution of the adsorbed particles, that is, the microstructure within the spherical monolayer induced by the external nanoparticle, which is also dependent on r₀, is elucidated by this analysis. It is found that the external particle needs to surmount a considerable potential barrier when moving toward the spherical surface, although much smaller than the one generated by a uniform surface distribution with an equivalent amount of charge. This is understood in terms of the correlation hole within the confined monolayer induced by the external particle. Another interesting conclusion is that the IEA provides an accurate, almost quantitative, description of the main features observed in the BD results, yet it is much less computationally demanding. The connection of these results with the overall chemical equilibrium of charged surfactant nanoparticles in the context of Pickering emulsions is also briefly discussed.

Spectroscopic signatures of localization with interacting photons in superconducting qubits

Quantized eigenenergies and their associated wave functions provide extensive information for predicting the physics of quantum many-body systems. Using a chain of nine superconducting qubits, we implement a technique for resolving the energy levels of interacting photons. We benchmark this method by capturing the main features of the intricate energy spectrum predicted for two-dimensional electrons in a magnetic field-the Hofstadter butterfly. We introduce disorder to study the statistics of the energy levels of the system as it undergoes the transition from a thermalized to a localized phase. Our work introduces a many-body spectroscopy technique to study quantum phases of matter.

The Langmuir-Hinshelwood approach for kinetic evaluation of cucurbit[7]uril-capped gold nanoparticles in the reduction of the antimicrobial nitrofurantoin

In this work, gold nanoparticles protected by the macrocycle cucurbit[7]uril were used as a catalyst in the reduction of the hazardous antimicrobial nitrofurantoin. 4-Nitrophenol was also employed as the substrate of the reduction for comparative purposes. The kinetic data were modeled to the Langmuir-Hinshelwood equation to know the affinities of the reactants for the surface and the real kinetic constants, a comparison at the molecular level that is made for the first time. From the results, it was observed that the adsorption of nitrofurantoin was stronger than that of 4-nitrophenol whilst the kinetic constant on the surface was higher for 4-nitrophenol than for nitrofurantoin. Additionally, shifts in the nanoparticle surface plasmon band permitted insights to be obtained into the adsorption rate and strength. The reaction induction times were also investigated and were highly dependent on the borohydride concentration and, due to the higher surface affinity of nitrofurantoin compared with 4-nitrophenol, an increase in nitrofurantoin concentration increased the induction time, while a lag phase was not observed for 4-nitrophenol.

Measurement-Induced State Transitions in a Superconducting Qubit: Beyond the Rotating Wave Approximation

Many superconducting qubit systems use the dispersive interaction between the qubit and a coupled harmonic resonator to perform quantum state measurement. Previous works have found that such measurements can induce state transitions in the qubit if the number of photons in the resonator is too high. We investigate these transitions and find that they can push the qubit out of the two-level subspace, and that they show resonant behavior as a function of photon number. We develop a theory for these observations based on level crossings within the Jaynes-Cummings ladder, with transitions mediated by terms in the Hamiltonian that are typically ignored by the rotating wave approximation. We find that the most important of these terms comes from an unexpected broken symmetry in the qubit potential. We confirm the theory by measuring the photon occupation of the resonator when transitions occur while varying the detuning between the qubit and resonator.

Design of a holographic tracking module for long-range retroreflector free-space systems

Weight reduction and low power consumption are key requirements in the next generation of unmanned aerial vehicles (UAVs). To communicate with an operator, a secured link between the UAV and a ground-based station is desirable. To realize these links, retroreflecting free-space optics is potentially attractive as it offers light weight and low complexity at the UAV. However, the base station requires a high-performance tracking module to enable a steady illumination of the UAV retroreflector. In this paper, we present the design and implementation of a tracking system, which consists of coarse tracking and holographic fine tracking modules working cooperatively. Using this system, experimental field trials were carried out by mounting a multiple-quantum-well-based modulated retroreflector on a commercial UAV. A 2 Mbps optical link was achieved with a bit error rate of ∼2×10^-4 at a link range of 300 m.

ID: 60: ZINC DEFICIENCY PRIMES THE LUNG FOR VENTILATOR INDUCED LUNG INJURY

Mechanical ventilation is a necessary intervention to support patients with lung injury and the acute respiratory distress syndrome (ARDS), but can also exacerbate injury through mechanical stress-activated signaling pathways. We show that stretch applied to cultured human lung cells, and to mouse lungs in vivo, induces robust expression of metallothionein, a potent anti-oxidant and cyto-protective molecule critical for cellular zinc homeostasis. Furthermore, genetic deficiency of murine metallothionein genes exacerbated lung injury caused by injurious mechanical ventilation, identifying an adaptive role for these genes in limiting lung injury. Stretch induction of metallothionein required zinc and the zinc binding transcription factor MTF-1. We further show that dietary zinc-deficiency in mice potentiates ventilator-induced lung injury, and that plasma zinc levels are significantly reduced in human patients with ARDS compared to healthy and non-ARDS ICU controls, as well as to other critically ill patients without ARDS. Taken together, our findings identify a novel adaptive response of the lung to stretch mediated by metallothionein and zinc. These results demonstrate that failure of stretch-adaptive responses play an important role in exacerbating ventilator-induced lung injury, and identify zinc and metallothionein as targets for developing lung-protective interventions in patients requiring mechanical ventilation.

Measuring and Suppressing Quantum State Leakage in a Superconducting Qubit

Leakage errors occur when a quantum system leaves the two-level qubit subspace. Reducing these errors is critically important for quantum error correction to be viable. To quantify leakage errors, we use randomized benchmarking in conjunction with measurement of the leakage population. We characterize single qubit gates in a superconducting qubit, and by refining our use of derivative reduction by adiabatic gate pulse shaping along with detuning of the pulses, we obtain gate errors consistently below 10^{-3} and leakage rates at the 10^{-5} level. With the control optimized, we find that a significant portion of the remaining leakage is due to incoherent heating of the qubit.

Cucurbit[7]uril-stabilized gold nanoparticles as catalysts of the nitro compound reduction reaction

Catalytic performance of cucurbit[7]uril-stabilized gold nanoparticles on the reduction reaction of 4-nitrophenol and nitrofurantoin.

Digital quantum simulation of fermionic models with a superconducting circuit

One of the key applications of quantum information is simulating nature. Fermions are ubiquitous in nature, appearing in condensed matter systems, chemistry and high energy physics. However, universally simulating their interactions is arguably one of the largest challenges, because of the difficulties arising from anticommutativity. Here we use digital methods to construct the required arbitrary interactions, and perform quantum simulation of up to four fermionic modes with a superconducting quantum circuit. We employ in excess of 300 quantum logic gates, and reach fidelities that are consistent with a simple model of uncorrelated errors. The presented approach is in principle scalable to a larger number of modes, and arbitrary spatial dimensions.

State preservation by repetitive error detection in a superconducting quantum circuit

Quantum computing becomes viable when a quantum state can be protected from environment-induced error. If quantum bits (qubits) are sufficiently reliable, errors are sparse and quantum error correction (QEC) is capable of identifying and correcting them. Adding more qubits improves the preservation of states by guaranteeing that increasingly larger clusters of errors will not cause logical failure-a key requirement for large-scale systems. Using QEC to extend the qubit lifetime remains one of the outstanding experimental challenges in quantum computing. Here we report the protection of classical states from environmental bit-flip errors and demonstrate the suppression of these errors with increasing system size. We use a linear array of nine qubits, which is a natural step towards the two-dimensional surface code QEC scheme, and track errors as they occur by repeatedly performing projective quantum non-demolition parity measurements. Relative to a single physical qubit, we reduce the failure rate in retrieving an input state by a factor of 2.7 when using five of our nine qubits and by a factor of 8.5 when using all nine qubits after eight cycles. Additionally, we tomographically verify preservation of the non-classical Greenberger-Horne-Zeilinger state. The successful suppression of environment-induced errors will motivate further research into the many challenges associated with building a large-scale superconducting quantum computer.

Optimal quantum control using randomized benchmarking

We present a method for optimizing quantum control in experimental systems, using a subset of randomized benchmarking measurements to rapidly infer error. This is demonstrated to improve single- and two-qubit gates, minimize gate bleedthrough, where a gate mechanism can cause errors on subsequent gates, and identify control crosstalk in superconducting qubits. This method is able to correct parameters so that control errors no longer dominate and is suitable for automated and closed-loop optimization of experimental systems.

Clinical diagnostic clues in Crohn's disease: a 41-year experience

Determining the diagnosis of Crohn's disease has been highly difficult mainly during the first years of this study carried out at the Pontificia Universidad Catolica (PUC) Clinical Hospital. For instance, it has been frequently confused with Irritable bowel syndrome and sometimes misdiagnosed as ulcerative colitis, infectious colitis or enterocolitis, intestinal lymphoma, or coeliac disease. Consequently, it seems advisable to characterize what the most relevant clinical features are, in order to establish a clear concept of Crohn's disease. This difficulty may still be a problem at other medical centers in developing countries. Thus, sharing this information may contribute to a better understanding of this disease. Based on the clinical experience gained between 1963 and 2004 and reported herein, the main clinical characteristics of the disease are long-lasting day and night abdominal pain, which becomes more intense after eating and diarrhoea, sometimes associated to a mass in the abdomen, anal lesions, and other additional digestive and nondigestive clinical features. Nevertheless, the main aim of this work has been the following: is it possible to make, in an early stage, the diagnosis of Crohn's disease with a high degree of certainty exclusively with clinical data?

Pervasive science

In this forum we celebrate research that helps to successfully bring the benefits of computing technologies to children, older adults, people with disabilities, and other populations that are often ignored in the design of mass-marketed products.

Juan Pablo Hourcade, Editor

Delayed presentation: negative pressure pulmonary hemorrhage

Negative pressure pulmonary hemorrhage (NPPH) is a rare, life-threatening complication that develops after an acute upper airway obstruction. A 26 year old, healthy African-American man with no underlying lung disease developed negative pressure pulmonary edema and subsequently NPPH during recovery from general anesthesia for elective spine surgery. Diagnostic bronchoscopy confirmed an alveolar source of the bleeding. Clinical improvement was quick with supportive care in the medical intensive care unit.

[Validation of a prognostic index through nutritional status indicators in patients with severe acute pancreatitis]

OBJECTIVE

To evaluate the accuracy of a previously proposed prognostic index of mortality determined by nutritional indicators in patients severe acute pancreatitis. Methods (study population, subjects, intervention): We evaluated used three nutritional status indicators (total lymphocyte count, creatinine/height index and subescapular skinfold) to determine an index associated to mortality prognosis in patients with severe acute pancreatitis.

RESULTS

We assessed 34 patients, who were divided according to their outcome into: a) survivor, b) dead. The vast majority showed a litiasic origin of the disease, which was present among men, predominantly. The index' results were found to be directly (positively) related to mortality probability, i.e., the closer the score was to 2,the more probability the patient had to die.

CONCLUSION

Even though we were able to prove association between the proposed index and the patient's prognosis, a larger sample is needed to validate this as a possible tool which could be used along other prognostic test such as APACHE II or Ranson scales.

A selective spectrofluorimetric method for carbendazim determination in oranges involving inclusion-complex formation with cucurbit[7]uril

The increase in fluorescence intensity with respect to carbendazim that occurs as a result of supramolecular-complex formation between carbendazim and cucurbit[7]uril has been studied. This host-guest interaction has been employed to develop a sensitive and selective method for benzoimidazole-type pesticide determination in fruit samples. The association constant and stoichiometry of the complex formed are reported herein, and the influence of experimental variables, such as the pH or ionic strength of the solution, on complex formation and the presence of interfering substances is also discussed. Under the optimal conditions found, the developed method allows the detection of carbendazim at a 5.0x10(-9)M level. To test the method, matrix solid phase dispersion was employed as a sample preparation method for carbendazim determination in orange samples with an RSD (%) (n=3) value of 5%. The LOD and LOQ values calculated for real samples were 0.10 and 0.52mg/kg, respectively, thus showing that the proposed method is sensitive enough to meet legal requirements.