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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.

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.Measurement-induced phases of quantum information have been observed in a system of 70 superconducting qubits. [ABSTRACT FROM AUTHOR]

Quantum error correction (QEC) provides a practical path to fault-tolerant quantum computing through scaling to large qubit numbers, assuming that physical errors are sufficiently uncorrelated in time and space. In superconducting qubit arrays, high-energy impact events can produce correlated errors, violating this key assumption. Following such an event, phonons with energy above the superconducting gap propagate throughout the device substrate, which in turn generate a temporary surge in quasiparticle (QP) density throughout the array. When these QPs tunnel across the qubits' Josephson junctions, they induce correlated errors. Engineering different superconducting gaps across the qubit's Josephson junctions provides a method to resist this form of QP tunneling. By fabricating all-aluminum transmon qubits with both strong and weak gap engineering on the same substrate, we observe starkly different responses during high-energy impact events. Strongly gap engineered qubits do not show any degradation in T_{1} during impact events, while weakly gap engineered qubits show events of correlated degradation in T_{1}. We also show that strongly gap engineered qubits are robust to QP poisoning from increasing optical illumination intensity, whereas weakly gap engineered qubits display rapid degradation in coherence. Based on these results, gap engineering mitigates the threat of high-energy impacts to QEC in superconducting qubit arrays.

Purpose: This study investigated the psychometric properties of a 4-second interval scoring modification of the Assessment of Problem-Solving in Play (ie, Assessment of Problem-Solving in Play 4-second interval scoring [APSP-4])., Methods: A total of 95 children (3-48 months) with or at high risk for neuromotor delay were assessed with the APSP-4 and Bayley Scales of Infant and Toddler Development-III (Bayley). APSP-4 and Bayley cognitive raw scores were compared by age (construct validity) and over time (responsiveness). Twenty percent of videos were scored twice for intra- and interrater reliability., Results: The APSP-4 demonstrated excellent interrater (intraclass correlations [ICCs] ≥ 0.96) and intrarater (ICCs ≥ 0.99) reliability and performed similar to Bayley cognitive raw scores at different ages ( r s > 0.5), and over time ( r  = 0.81). The motor delay had similar effects on APSP-4 and Bayley scores., Conclusions: Results support the validity and reliability evidence of the APSP-4 for use over time in tracking problem-solving skills in young children aged 3 to 48 months. Future research investigating clinical implementation of the APSP-4 is needed., (Copyright © 2024 Academy of Pediatric Physical Therapy of the American Physical Therapy Association.)

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.

Evidence on the use of biomarkers to detect bladder cancer in the general population is scarce. This study aimed to systematically review evidence on the diagnostic performance of biomarkers which might be suitable for use in community and primary care settings [PROSPERO Registration: CRD42021258754]. Database searches on MEDLINE and EMBASE from January 2000 to May 2022 resulted in 4914 unique citations, 44 of which met inclusion criteria. Included studies reported on 112 biomarkers and combinations. Heterogeneity of designs, populations and outcomes allowed for the meta-analysis of three biomarkers identified in at least five studies (NMP-22, UroVysion, uCyt+). These three biomarkers showed similar discriminative ability (adjusted AUC estimates ranging from 0.650 to 0.707), although for NMP-22 and UroVysion there was significant unexplained heterogeneity between included studies. Narrative synthesis revealed the potential of these biomarkers for use in the general population based on their reported clinical utility, including effects on clinicians, patients, and the healthcare system. Finally, we identified some promising novel biomarkers and biomarker combinations ( N < 3 studies for each biomarker/combination) with negative predictive values of ≥90%. These biomarkers have potential for use as a triage tool in community and primary care settings for reducing unnecessary specialist referrals. Despite promising emerging evidence, further validation studies in the general population are required at different stages within the diagnostic pathway.

Aims: Children with neuromotor delays are at risk for reaching and object exploration impairments, which may negatively affect their cognitive development and daily activity performance. This study evaluated the effectiveness of the Sitting Together And Reaching To Play (START-Play) intervention on reaching-related exploratory behaviors in children with neuromotor delays., Methods: In this randomized controlled clinical trial, 112 children ( Mean  = 10.80, SD  = 2.59 months old at baseline) with motor delays were randomly assigned to receive START-Play intervention or usual care-early intervention. Performance for ten reaching-related exploratory behaviors was assessed at baseline and 1.5, 3, 6, 12 months post-baseline. Piecewise linear mixed-effects modeling was used to evaluate short- and long-term effects of the intervention., Results: Benefits of START-Play were observed for children with significant motor delays, but not for those with mild delays. START-Play was especially beneficial for children with significant motor delays who demonstrated early mastery in the reaching assessment (i.e., object contact ≥65% of the time within 3 months after baseline); these children showed greater improvements in manual, visual, and multimodal exploration, as well as intensity of exploration across time., Conclusions: START-Play advanced the performance of reaching-related exploratory behaviors in children with significant motor delays.