Logical quantum processor based on reconfigurable atom arrays.

Suppressing errors is the central challenge for useful quantum computing1, requiring quantum error correction (QEC)2-6 for large-scale processing. However, the overhead in the realization of error-corrected 'logical' qubits, in which information is encoded across many physical qubits for redundancy2-4, poses substantial challenges to large-scale logical quantum computing. Here we report the realization of a programmable quantum processor based on encoded logical qubits operating with up to 280 physical qubits. Using logical-level control and a zoned architecture in reconfigurable neutral-atom arrays7, our system combines high two-qubit gate fidelities8, arbitrary connectivity7,9, as well as fully programmable single-qubit rotations and mid-circuit readout10-15. Operating this logical processor with various types of encoding, we demonstrate improvement of a two-qubit logic gate by scaling surface-code6 distance from d = 3 to d = 7, preparation of colour-code qubits with break-even fidelities5, fault-tolerant creation of logical Greenberger-Horne-Zeilinger (GHZ) states and feedforward entanglement teleportation, as well as operation of 40 colour-code qubits. Finally, using 3D [[8,3,2]] code blocks16,17, we realize computationally complex sampling circuits18 with up to 48 logical qubits entangled with hypercube connectivity19 with 228 logical two-qubit gates and 48 logical CCZ gates20. We find that this logical encoding substantially improves algorithmic performance with error detection, outperforming physical-qubit fidelities at both cross-entropy benchmarking and quantum simulations of fast scrambling21,22. These results herald the advent of early error-corrected quantum computation and chart a path towards large-scale logical processors.

High-fidelity parallel entangling gates on a neutral-atom quantum computer.

The ability to perform entangling quantum operations with low error rates in a scalable fashion is a central element of useful quantum information processing1. Neutral-atom arrays have recently emerged as a promising quantum computing platform, featuring coherent control over hundreds of qubits2,3 and any-to-any gate connectivity in a flexible, dynamically reconfigurable architecture4. The main outstanding challenge has been to reduce errors in entangling operations mediated through Rydberg interactions5. Here we report the realization of two-qubit entangling gates with 99.5% fidelity on up to 60 atoms in parallel, surpassing the surface-code threshold for error correction6,7. Our method uses fast, single-pulse gates based on optimal control8, atomic dark states to reduce scattering9 and improvements to Rydberg excitation and atom cooling. We benchmark fidelity using several methods based on repeated gate applications10,11, characterize the physical error sources and outline future improvements. Finally, we generalize our method to design entangling gates involving a higher number of qubits, which we demonstrate by realizing low-error three-qubit gates12,13. By enabling high-fidelity operation in a scalable, highly connected system, these advances lay the groundwork for large-scale implementation of quantum algorithms14, error-corrected circuits7 and digital simulations15.

The role of rumination in the relationship between symptoms of insomnia and depression in adolescents.

There is a strong relationship between the symptoms of insomnia and depression, however, little is understood about the factors that mediate this relationship. An understanding of these underlying mechanisms may inform the advancement of existing treatments to optimise reductions in insomnia and depression when they co-occur. This study examined rumination and unhelpful beliefs about sleep as mediators between symptoms of insomnia and depression. It also evaluated the effect of cognitive behavioural therapy for insomnia (CBT-I) on rumination and unhelpful beliefs about sleep, and whether these factors mediated the effect of CBT-I on depressive symptoms. A series of mediation analyses and linear mixed modelling were conducted on data from 264 adolescents (12-16 years) who participated in a two-arm (intervention vs. control) randomised controlled trial of Sleep Ninja®, a CBT-I smartphone app for adolescents. Rumination, but not unhelpful beliefs about sleep, was a significant mediator between symptoms of insomnia and depression at baseline. CBT-I led to reductions in unhelpful beliefs about sleep, but not in rumination. At the between-group level, neither rumination, nor unhelpful beliefs about sleep emerged as mechanisms underlying improvement in depression symptoms, however, rumination mediated within-subject improvements following CBT-I. The findings suggest rumination links symptoms of insomnia and depression and provide preliminary evidence that reductions in depression following CBT-I occurs via improvements in rumination. Targeting rumination may improve current therapeutic approaches.

Cognitive behavior therapy for insomnia in university students delivered via videoconferencing groups: A pilot study.

INTRODUCTION: Sleep difficulties are common amongst university students and are associated with mental illness and reduced wellbeing. This paper reports a pilot study of Cognitive Behavior Therapy for Insomnia (CBT-I) tailored specifically for university students. It was hypothesized that the intervention would be feasible, acceptable, and improve sleep, anxiety, depression, and wellbeing. METHOD: Students aged 18-25 participated via videoconferencing small group sessions of CBT-I. Feasibility was assessed through sign-up, consent rates, and study attrition, while acceptability was assessed using intervention adherence and a measure of intervention acceptability. Outcome measures included sleep quality, insomnia, suicidal ideation, symptoms of depression, anxiety, and wellbeing, and were assessed at baseline and post-intervention. RESULTS: Participants were 44 students (M = 21.8 years). Feasibility was confirmed by sign-up and consent rates (80% of the students who expressed interest agreed to participate); overall study attrition was 48%, comprised largely of participants not commencing treatment (27%). Participants perceived the program as effective and logical and made use of the skills suggested. In terms of adherence, 82% of the participants who engaged with treatment attended two or more sessions and 63% attended all four sessions; and 92% were either very satisfied or mostly satisfied. Sleep quality, insomnia, depression, anxiety, and wellbeing all significantly improved from pre- to post-intervention. DISCUSSION: There was evidence that the CBT-I intervention tailored for university students was acceptable to participants and could be feasible to deliver. Sleep quality, depression, anxiety, and wellbeing improved significantly. These findings suggest that the intervention is suitable for evaluation in a fully powered randomized controlled trial.

The effects of a sleep-focused smartphone application on insomnia and depressive symptoms: a randomised controlled trial and mediation analysis.

BACKGROUND: Rates of depression are increasing among adolescents. A novel way to reduce depression is by improving sleep. We evaluated whether an app-based intervention for insomnia improved sleep and depression, and whether changes in insomnia mediated changes in depression. METHODS: We conducted a 2-arm single-blind randomised controlled trial at the Black Dog Institute in Australia. Adolescents 12-16 years experiencing insomnia symptoms were randomly allocated to receive Sleep Ninja, an app-delivered cognitive behavioural therapy program for insomnia, or to an active control group involving weekly text message sleep tips. Assessments took place at baseline, 6 weeks (post-intervention) and 14 weeks (post-baseline). Co-primary outcomes were symptoms of insomnia and depression at post-intervention (primary endpoint). Intent-to-treat analyses were conducted. The trial is registered with the Australian and New Zealand Clinical Trials Registry, number ACTRN12619001462178. RESULTS: Between October 25, 2019, and September 6, 2020, 264 participants were randomised to receive Sleep Ninja (n = 131) or to the control group (n = 133). Relative to the control group, those allocated to the intervention reported a greater reduction in insomnia symptoms at 6 weeks (95% CI: -2.96 to -0.41, d = .41) and 14 weeks (95% CI: -3.34 to -0.19, d = .39), and a greater reduction in depression symptoms at 6 weeks (95% CI: -3.46 to -0.56, d = .28) but not 14 weeks (p < 1). Change in insomnia mediated change in depression. No adverse events were reported. CONCLUSIONS: An app-delivered program for insomnia could be a practical, non-stigmatising and scalable way to reduce symptoms of insomnia and depression among adolescents experiencing difficulties getting enough good quality sleep.

Impact of COVID-19 on electroconvulsive therapy practice across Canadian provinces during the first wave of the pandemic.

BACKGROUND: Electroconvulsive therapy (ECT) is a procedural treatment that is potentially life-saving for some patients with severe psychiatric illness. At the start of the global coronavirus disease 2019 (COVID-19) pandemic, ECT practice was remarkably disrupted, putting vulnerable individuals at increased risk of symptom exacerbation and death by suicide. This study aimed to capture the self-reported experiences of psychiatrists based at healthcare facilities across Canadian provinces who were delivering ECT treatments during the first phase of the COVID-19 pandemic (i.e., from mid-March 2020 to mid-May 2020). METHODS: A multidisciplinary team of experts developed a survey focusing on five domains: ECT unit operations, decision-making, hospital resources, ECT procedure, and mitigating patient impact. Responses were collected from psychiatrists providing ECT at 67 ECT centres in Canada, grouped by four geographical regions (Ontario, Quebec, Atlantic Canada, and Western Canada). RESULTS: Clinical operations of ECT programs were disrupted across all four regions - however, centres in Atlantic Canada were able to best preserve outpatient and maintenance care, while centres in Western Canada were able to best preserve inpatient and acute care. Similarly, Atlantic and Western Canada demonstrated the best decision-making practices of involving the ECT team and clinical ethicists in the development of pandemic-related guidelines. Across all four regions, ECT practice was affected by the redeployment of professionals, the shortage of personal protective equipment, and the need to enforce social distancing. Attempts to introduce modifications to the ECT delivery room and minimize bag-valve-mask ventilation were consistently reported. All four regions developed a new patient prioritization framework, and Western Canada, notably, aimed to provide ECT to only the most severe cases. CONCLUSIONS: The results suggest that ECT provision was disproportionately affected across different parts of Canada. Possible factors that could explain these interregional differences include population, distribution of urban vs. rural areas, pre-pandemic barriers in access to ECT, number of cases, ability to control the spread of infection, and the general reduction in physicians' activities across different areas of health care. Studying these factors in the future will inform how medical centres should respond to public health emergencies and pandemic-related circumstances in the context of procedural treatments.

PARP1- and CTCF-Mediated Interactions between Active and Repressed Chromatin at the Lamina Promote Oscillating Transcription.

Transcriptionally active and inactive chromatin domains tend to segregate into separate sub-nuclear compartments to maintain stable expression patterns. However, here we uncovered an inter-chromosomal network connecting active loci enriched in circadian genes to repressed lamina-associated domains (LADs). The interactome is regulated by PARP1 and its co-factor CTCF. They not only mediate chromatin fiber interactions but also promote the recruitment of circadian genes to the lamina. Synchronization of the circadian rhythm by serum shock induces oscillations in PARP1-CTCF interactions, which is accompanied by oscillating recruitment of circadian loci to the lamina, followed by the acquisition of repressive H3K9me2 marks and transcriptional attenuation. Furthermore, depletion of H3K9me2/3, inhibition of PARP activity by olaparib, or downregulation of PARP1 or CTCF expression counteracts both recruitment to the envelope and circadian transcription. PARP1- and CTCF-regulated contacts between circadian loci and the repressive chromatin environment at the lamina therefore mediate circadian transcriptional plasticity.

The relationship between repetitive negative thinking, sleep disturbance, and subjective fatigue in women with Generalized Anxiety Disorder.

OBJECTIVES: Fatigue is a prominent symptom of Generalized Anxiety Disorder (GAD). However, the pathways contributing to elevated fatigue in GAD are poorly understood. Sleep disturbance, also prominent in GAD, only partially explains elevated fatigue in GAD. Repetitive negative thinking (RNT) is a cognitive feature of both GAD and sleep disturbance, and RNT has recently also been associated with elevated fatigue. Therefore, this study assessed whether elevated fatigue in GAD is accounted for by a combination of sleep quality and RNT. DESIGN: Between-group, correlational design in 64 primarily university-educated women with and without a GAD diagnosis. METHODS: Women completed self-report questionnaires assessing RNT experienced in the past few days, previous night's sleep quality, and current physical and mental fatigue. Hierarchical linear regressions were conducted to assess whether the relationship between GAD status and fatigue is accounted for by RNT and sleep quality. RESULTS: Women with GAD reported lower sleep quality, and higher RNT and physical and mental fatigue, compared to women without GAD. Sleep quality partly accounted for group differences in both types of fatigue (ß's > -0.4), whereas RNT fully accounted for group differences in both types of fatigue (ß's > 0.29). The relationship between RNT and both types of fatigue was fully accounted for by sleep quality (ß's > -0.39). CONCLUSIONS: These findings indicate that heightened RNT amongst women with GAD may be associated with elevated physical and mental fatigue via its detrimental effects on sleep quality. Interventions that reduce RNT may help to alleviate fatigue symptoms in women with GAD. PRACTITIONER POINTS: Women with Generalized Anxiety Disorder (GAD) have elevated fatigue and repetitive negative thinking (RNT), and poorer self-reported sleep quality, relative to women without GAD. Whereas sleep quality only partially accounts for elevated fatigue in GAD, RNT fully accounts for elevated fatigue, and the relationship between RNT and fatigue is fully accounted for by sleep quality. These findings provide novel evidence that women with GAD may have elevated fatigue because of the detrimental effects of RNT on sleep. These findings suggest that targeting RNT in treatment for GAD may help to reduce fatigue in GAD, by improving sleep quality.

The impact of COVID-19 on the lives and mental health of Australian adolescents.

There has been significant disruption to the lives and mental health of adolescents during the COVID-19 pandemic. The purpose of this study was to assess the psychological and lifestyle impact of the pandemic on Australian adolescents, using an online survey, administered during the outbreak. Self-report surveys were administered online to a sample of 760 Australian adolescents aged 12-18 years assessing impact on a range of domains including behaviour, education, relationships, lifestyle factors (exercise, technology use, and sleep), and mental health outcomes (psychological distress, loneliness, health anxiety and well-being). Results showed that three quarters of the sample experienced a worsening in mental health, since the pandemic began, with negative impacts reported on learning, friendships and family relationships. There were also high higher levels of sleep disturbance, psychological distress and health anxiety, relative to normative samples. Effects on mental health were worse among those who reported a previous diagnosis of depression and/or anxiety relative to those without no such history. Adolescents are already vulnerable to the onset of mental illness at this developmental stage, and the current research underscores the need to find rapid and accessible ways to support adolescent mental health during times of crisis.

Appraisal of systematic reviews on interventions for postpartum depression: systematic review.

BACKGROUND: Postpartum depression (PPD) is a highly prevalent mental health problem that affects parental health with implications for child health in infancy, childhood, adolescence and beyond. The primary aim of this study was to critically appraise available systematic reviews describing interventions for PPD. The secondary aim was to evaluate the methodological quality of the included systematic reviews and their conclusions. METHODS: An electronic database search of MEDLINE, Embase, and the Cochrane Library from 2000 to 2020 was conducted to identify systematic reviews that examined an intervention for PPD. A Measurement Tool to Assess Systematic Reviews was utilized to independently score each included systematic review which was then critically appraised to better define the most effective therapeutic options for PPD. RESULTS: Of the 842 studies identified, 83 met the a priori criteria for inclusion. Based on the systematic reviews with the highest methodological quality, we found that use of antidepressants and telemedicine were the most effective treatments for PPD. Symptoms of PPD were also improved by traditional herbal medicine and aromatherapy. Current evidence for physical exercise and cognitive behavioural therapy in treating PPD remains equivocal. A significant, but weak relationship between AMSTAR score and journal impact factor was observed (p = 0.03, r = 0.24; 95% CI, 0.02 to 0.43) whilst no relationship was found between the number of total citations (p = 0.27, r = 0.12; 95% CI, - 0.09 to 0.34), or source of funding (p = 0.19). CONCLUSION: Overall the systematic reviews on interventions for PPD are of low-moderate quality and are not improving over time. Antidepressants and telemedicine were the most effective therapeutic interventions for PPD treatment.