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Measurement has a special role in quantum theory 1 : by collapsing the wavefunction, it can enable phenomena such as teleportation 2 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–time 3 – 10 that go beyond the established paradigms for characterizing phases, either in or out of equilibrium 11 – 13 . For present-day noisy intermediate-scale quantum (NISQ) processors 14 , 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 mapping 9 , 15 – 17 to avoid mid-circuit measurement and access different manifestations of the underlying phases, from entanglement scaling 3 , 4 to measurement-induced teleportation 18 . 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.

Indistinguishability of particles is a fundamental principle of quantum mechanics 1 . 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 protocol 23 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. A unitary protocol for braiding projective non-Abelian Ising anyons in a generalized stabilizer code is implemented on a superconducting processor, allowing for verification of their fusion rules and realization of their exchange statistics.

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 particles 1 . 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 states 2 – 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. An experimental investigation of the dynamics of the spin ½ Floquet XXZ model finds bound states as predicted, and also robustness to noise and non-integrability when theoretical descriptions start to fail.

Cerebral venous thrombosis (CVT) is a cerebrovascular disorder caused by complete or partial occlusion of the cerebral venous and sinus system. The etiology has been attributed to hypercoagulability and pro-thrombotic states, leading to raised intracranial pressures that often manifest as headaches and focal neurological deficits. However, the multifactorial nature of CVT can create a diagnostic conundrum for clinicians. We describe a unique case of a 16-year-old female who presented with convulsions, postictal confusion, and drowsiness followed by residual weakness of her extremities. She initially presented to the primary care center with headache, high-grade fever, and altered mental status and was empirically treated for pyogenic meningitis. The patient failed to improve with a week of antibiotics and was referred to the tertiary care center for urgent attention. On presentation, the patient developed VI and VII cranial nerve palsy. Subsequently, MRI images showed filling defects in the superior sagittal, right transverse, and sigmoid sinuses with right parietal gyral T1 hyperintensity and T2 hypo-intensity. She was diagnosed with septic CVT based on sinus venous thrombosis and venous infarction, probably secondary to meningococcal pneumonia. It can be challenging to distinguish between both conditions as their presentations overlap. Moreover, cranial nerve palsy is an infrequent manifestation of CVT, with unclear pathogenesis. We highlight the role of neuro-imaging in the early detection of CVT and bring to light the unfamiliar symptoms and a more varied clinical spectrum that may hinder the diagnosis in a limited-resource setting. Future research should be explicitly modeled to improve the diagnostic efficiency of CVT and improve outcomes in younger patient populations.

We report transport measurements of electrons on helium in a microchannel device where the channels are 200 nm deep and 3 μ m wide. The channels are fabricated above amorphous metallic Ta 40 W 40 Si 20 , which has surface roughness below 1 nm and minimal variations in work function across the surface due to the absence of polycrystalline grains. We are able to set the electron density in the channels using a ground plane. We estimate a mobility of 300 cm 2 / V s and electron densities as high as 2.56 × 10 9 cm - 2 . We demonstrate control of the transport using a barrier which enables pinch-off at a central microchannel connecting two reservoirs. The conductance through the central microchannel is measured to be 10 nS for an electron density of 1.58 × 10 9 cm - 2 . Our work extends transport measurements of surface electrons to thin helium films in microchannel devices above metallic substrates.

Timely access to medical care is an important determinant of health and well-being. The US Congress passed the Veterans Access, Choice, and Accountability Act in 2014 and the VA MISSION (Maintaining Systems and Strengthening Integrated Outside Networks) Act in 2018, both of which allow veterans to access care from community-based clinicians, but geographic variation in appointment wait times after the passage of these acts have not been studied. To describe geographic variation in wait times experienced by veterans for primary care, mental health, and other specialties. This is a cross-sectional study using data from the Veterans Health Administration (VHA) Corporate Data Warehouse. Participants include veterans who sought medical care from January 1, 2018, to June 30, 2021. Data analysis was performed from February to June 2022. Referral to either VHA or community-based clinicians. Total appointment wait times (in days) for 3 care categories: primary care, mental health, and all other specialties. VHA medical centers are organized into regions called Veterans Integrated Services Networks (VISNs); wait times were aggregated to the VISN level. The final sample included 22 632 918 million appointments for 4 846 892 unique veterans (77.3% male; mean [SD] age, 61.6 [15.5] years). Among non-VHA appointments, mean (SD) VISN-level appointment wait times were 38.9 (8.2) days for primary care, 43.9 (9.0) days for mental health, and 41.9 (5.9) days for all other specialties. Among VHA appointments, mean (SD) VISN-level appointment wait times were 29.0 (5.5) days for primary care, 33.6 (4.6) days for mental health, and 35.4 (2.7) days for all other specialties. There was substantial geographic variation in appointment wait times. Among non-VHA appointments, VISN-level appointment wait times ranged from 25.4 to 52.4 days for primary care, from 29.3 to 65.7 days for mental health, and from 34.7 to 54.8 days for all other specialties. Among VHA appointments, wait times ranged from 22.4 to 43.4 days for primary care, from 24.7 to 42.0 days for mental health, and from 30.3 to 41.9 days for all other specialties. There was a correlation between wait times across care categories and setting (VHA vs community care). This cross-sectional study found substantial variation in wait times across care type and geography, and VHA wait times in a majority of VISNs were lower than those for community-based clinicians, even after controlling for differences in specialty mix. These findings suggest that liberalized access to community care under the Veterans Access, Choice, and Accountability Act and the VA MISSION Act may not result in lower wait times within these regions.

This study describes health-related quality of life (HRQoL) among older Medicare beneficiaries with hormone receptor-positive (HR+) early breast cancer (eBC). Women aged ≥65 years diagnosed with stage I-III HR+ eBC between 1997 and 2014 using the Surveillance, Epidemiology, and End Results Medicare Health Outcomes Survey Data Resource were included. HRQoL was measured using the Short Form Health Survey including physical/mental component summary (PCS/MCS) scores and subscales. Patient surveys  ≤ 24 months post-diagnosis were matched to non-cancer controls. Mean differences in HRQoL were compared using analysis of covariance. Among 1880 HR+ eBC patients versus 5640 matched non-cancer controls, eBC patients surveyed  ≤ 6 months post-diagnosis (n  =  530) scored lower on component scores (PCS mean difference  =  1.6 [95%CI: 0.6-2.6]; MCS mean difference  =  2.0 [95%CI: 1.0-3.0]) and multiple subscales. Among women surveyed 19 to 24 months post-diagnosis (n  =  402), mean differences in HRQoL were modest (PCS: 1.2 [95%CI: 0.1-2.4]; MCS: −1.5 [95%CI: −2.7 to −0.3]). Most differences in HRQoL following diagnosis of eBC did not indicate statistical significance or minimally important difference, emphasizing that preservation of HRQoL is an important and realistic goal among patients with eBC.

Women with hormone receptor (HR)-positive early-stage breast cancer (BC) have five-year survival rates of > 90% but remain at serious risk for developing distant metastases beyond five years from diagnosis. This retrospective cohort study used data from the Surveillance, Epidemiology, and End Results (SEER) registries to examine associations between distant recurrence-free interval (DRFI) and risk of BC-specific mortality following distant relapse. The analysis includes 1,057 women with second primary stage IV BC who were initially diagnosed with AJCC stages I–III HR-positive BC between1990 and 2016. Overall, 65% of women had a preceding DRFI of ≥ 5 years. Five-year BC-specific survival following development of distant recurrence was 52% for women with DRFI ≥ 5 years compared to 31% in women with DRFI of < 5 years. In multivariable analyses, risks of cancer-specific mortality following distant recurrence were lower in women with DRFI of 5 years or more (subdistribution hazard ratio = 0.72, 95% CI 0.58–0.89, p = 0.002). The results of this study may inform patient-clinician discussions surrounding prognosis and treatment selection among HR-positive patients who develop a distant recurrence of disease.

Purpose To examine the impact of pre-diagnosis depressive symptoms and mental health-related quality of life (HRQOL) on survival among older patients with multiple myeloma (MM). Methods We performed a retrospective cohort study using the Surveillance, Epidemiology, and End Results-Medicare Health Outcomes Survey data resource. Patients aged 65 years and older diagnosed with first primary MM between 1998 and 2014 were identified, and presence of depressive symptoms was determined based on responses to 3 depression screening questions prior to MM diagnosis. Veterans RAND 12 mental component summary (MCS) scores were analyzed to evaluate mental HRQOL. We used multivariable Cox proportional hazards models to estimate hazard ratios (HR) and 95% confidence intervals (CI) for risks of all-cause and cancer-specific mortality. Results Of 522 patients, mean (SD) age at diagnosis was 76.9 (6.1) years and 158 (30%) reported depressive symptoms. Patients with depressive symptoms had a higher number of comorbid conditions and nearly all (84%) scored below the median MCS. Pre-diagnosis depressive symptoms were not associated with all-cause (HR = 1.01, 95% CI 0.79–1.29) or cancer-specific mortality (HR = 0.94, 95% CI 0.69–1.28). MM patients scoring in the second MCS tertile (vs the highest tertile) had a modestly increased risk of all-cause (HR = 1.19, 95% CI 0.91–1.55) and cancer-specific mortality (HR = 1.17, 95% CI 0.86–1.60), but these estimates were not statistically significant. Conclusion Pre-diagnosis depressive symptoms and lower mental HRQoL did not impact survival among older MM patients. Highly prevalent depressive symptoms among older MM patients deserve clinical attention. Such efforts can inform clinicians in tailoring care for this vulnerable population.