Efficacy and safety of left atrial appendage closure in patients with atrial fibrillation and high thromboembolic and bleeding risk

Aim. To compare the incidence of thromboembolic and hemorrhagic events after left atrial appendage occlusion (LAAO) or without prevention of thromboembolic events (TEEs) during prospective follow-up of patients with atrial fibrillation (AF) and a high risk of ischemic stroke (IS) who have contraindications to long-term anticoagulant therapy.Material and methods. The study included 134 patients with AF, a high risk of IS, and contraindications to long-term anticoagulation. Patients were divided into 2 groups as follows: the first group included patients who underwent LAAO (n=74), while the second one — those who did not undergo any TEE prevention (n=60). The follow-up period was 3 years. The cumulative rate of all-cause mortality, IS, transient ischemic attacks (TIA), and systemic embolism (SE) was taken as the primary efficacy endpoint. The primary safety endpoint included major bleeding according to GARFIELD registry criteria.Results.  The rate of composite efficacy endpoint in the LAAO group was significantly lower than in the group without thromboembolic prophylaxis (5,2 vs 17,4 per 100 patient-years; adjusted odds ratio (OR), 4,08; 95% confidence interval (CI): 1,7-9,5; p=0,001). The rate of major bleeding was comparable in both groups (2,4 in the LAAO group vs 1,3 per 100 patient-years in the group without thromboembolic prophylaxis; adjusted OR, 0,55; 95% CI: 0,1-3,09; p=0,509). In addition, the event rate of net clinical benefit (all-cause mortality + ischemic stroke/TIA/SE + major bleeding) in the LAAO group was also significantly lower (5,9 vs 18,2 per 100 patient-years; adjusted OR, 3,0; 95% CI: 1,47-6,36; p=0,003).Conclusion. Among patients with AF and contraindications to long-term anticoagulation after 3 years of follow-up, LAAO demonstrated the significant reduction of cumulative rate of all-cause mortality and non-fatal thromboembolic events. At the same time, the frequency of major bleeding was comparable between the groups, even taking into account access-site bleeding and postoperative antithrombotic therapy (ATT)-associated bleeding in the LAAO group. Further randomized clinical trials are required to confirm these data

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

Продленная заместительная почечная терапия с применением мембран с повышенной сорбционной емкостью у пациентов после нейрохирургических вмешательств с септическим шоком

Introduction. The combination of primary brain injury with cytokine storm and hemodynamic disturbance in septic shock leads to secondary brain damage and growing neurological deficit. Blood purification procedures can be considered as an additional option in the treatment of septic shock in this group of patients.Subjects and Methods. The study included 11 patients after neurosurgical interventions with septic shock and acute kidney injury who underwent continuous renal replacement therapy (CRRT) using membranes with increased adsorption capacity.Results. During CRRT there was a significant regression in severity of multiorgan dysfunction according to SOFA score, a decrease in the requirement for vasopressor support with norepinephrine, and a decrease in lactate blood level. In addition, after the end of the procedure, there was a significant decrease in procalcitonin blood level. Septic shock reversal was observed in 8/11 patients (72.7%). In 3/11 patients, neurological deficits regressed during the procedure.Conclusions. The results indicate the possibility of using CRRT with membranes with increased adsorption capacity in patients after neurosurgical interventions with septic shock. Changes in neurological status can be considered as an additional parameter for the effectiveness of therapy for septic shock in patients with primary brain injury.Сочетание первичной патологии головного мозга с цитокиновым штормом и нарушением гемодинамики при септическом шоке приводит к вторичному повреждению головного мозга и нарастанию неврологического дефицита. Проведение процедур экстракорпоральной детоксикации может быть рассмотрено в качестве дополнительной опции терапии септического шока у пациентов данной группы.Материал и методы. В исследование включены 11 пациентов после нейрохирургических вмешательств с септическим шоком и острым почечным повреждением, которым проводили продленную заместительную почечную терапию (ПЗПТ) с применением мембран с повышенной сорбционной емкостью.Результаты. На фоне интенсивной терапии септического шока с применением ПЗПТ обнаружены значимый регресс тяжести мультиорганной дисфункции по шкале SOFA, снижение потребности в вазопрессорной поддержке норадреналином и уровня лактата в крови. Кроме того, после окончания процедуры установлено значимое снижение уровня прокальцитонина в крови. Выход из септического шока был отмечен у 8/11 пациентов (72,7%), регресс неврологического дефицита на фоне процедуры ‒ у 3/11 пациентов.Выводы. Полученные результаты свидетельствуют о возможности применения ПЗПТ с мембранами с повышенной сорбционной емкостью у пациентов после нейрохирургических вмешательств с септическим шоком. Динамика неврологического статуса может быть рассмотрена в качестве дополнительного критерия эффективности терапии септического шока у пациентов с первичным церебральным повреждением

Phase transition in Random Circuit Sampling

Quantum computers hold the promise of executing tasks beyond the capability of classical computers. Noise competes with coherent evolution and destroys long-range correlations, making it an outstanding challenge to fully leverage the computation power of near-term quantum processors. We report Random Circuit Sampling (RCS) experiments where we identify distinct phases driven by the interplay between quantum dynamics and noise. Using cross-entropy benchmarking, we observe phase boundaries which can define the computational complexity of noisy quantum evolution. We conclude by presenting an RCS experiment with 70 qubits at 24 cycles. We estimate the computational cost against improved classical methods and demonstrate that our experiment is beyond the capabilities of existing classical supercomputers

Overcoming leakage in scalable quantum error correction

Leakage of quantum information out of computational states into higher energy states represents a major challenge in the pursuit of quantum error correction (QEC). In a QEC circuit, leakage builds over time and spreads through multi-qubit interactions. This leads to correlated errors that degrade the exponential suppression of logical error with scale, challenging the feasibility of QEC as a path towards fault-tolerant quantum computation. Here, we demonstrate the execution of a distance-3 surface code and distance-21 bit-flip code on a Sycamore quantum processor where leakage is removed from all qubits in each cycle. This shortens the lifetime of leakage and curtails its ability to spread and induce correlated errors. We report a ten-fold reduction in steady-state leakage population on the data qubits encoding the logical state and an average leakage population of less than $1 \times 10^{-3}$ throughout the entire device. The leakage removal process itself efficiently returns leakage population back to the computational basis, and adding it to a code circuit prevents leakage from inducing correlated error across cycles, restoring a fundamental assumption of QEC. With this demonstration that leakage can be contained, we resolve a key challenge for practical QEC at scale.Comment: Main text: 7 pages, 5 figure

Measurement-induced entanglement and teleportation on a noisy quantum processor

Measurement has a special role in quantum theory: by collapsing the wavefunction it can enable phenomena such as teleportation 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 that go beyond established paradigms for characterizing phases, either in or out of equilibrium. On present-day NISQ processors, the experimental realization of this physics is challenging due to noise, hardware limitations, and the stochastic nature of quantum measurement. Here we address each of these experimental challenges and investigate measurement-induced quantum information phases on up to 70 superconducting qubits. By leveraging the interchangeability of space and time, we use a duality mapping, to avoid mid-circuit measurement and access different manifestations of the underlying phases -- from entanglement scaling to measurement-induced teleportation -- in a unified way. We obtain finite-size signatures of a phase transition with a decoding protocol that correlates the experimental measurement record with classical simulation data. The phases display sharply different sensitivity to noise, which we exploit to turn an inherent hardware limitation into a useful diagnostic. Our work demonstrates an approach to realize 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 mechanics. 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. However, in two spatial dimensions, an intriguing possibility exists: braiding of non-Abelian anyons causes rotations in a space of topologically degenerate wavefunctions. 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, 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. While efforts on conventional solid-state platforms typically involve Hamiltonian dynamics of quasi-particles, superconducting quantum processors allow for directly manipulating the many-body wavefunction via unitary gates. Building on predictions that stabilizer codes can host projective non-Abelian Ising anyons, we implement a generalized stabilizer code and unitary protocol 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 employing the anyons for quantum computation and utilize 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 toward fault-tolerant quantum computing

Realizing topologically ordered states on a quantum processor

The discovery of topological order has revolutionized the understanding of quantum matter in modern physics and provided the theoretical foundation for many quantum error correcting codes. Realizing topologically ordered states has proven to be extremely challenging in both condensed matter and synthetic quantum systems. Here, we prepare the ground state of the toric code Hamiltonian using an efficient quantum circuit on a superconducting quantum processor. We measure a topological entanglement entropy near the expected value of $\ln2$, and simulate anyon interferometry to extract the braiding statistics of the emergent excitations. Furthermore, we investigate key aspects of the surface code, including logical state injection and the decay of the non-local order parameter. Our results demonstrate the potential for quantum processors to provide key insights into topological quantum matter and quantum error correction.Comment: 6 pages 4 figures, plus supplementary material