Strong Zero Modes from Geometric Chirality in Quasi-One-Dimensional Mott Insulators.

Strong zero modes provide a paradigm for quantum many-body systems to encode local degrees of freedom that remain coherent far from the ground state. Example systems include Z_{n} chiral quantum clock models with strong zero modes related to Z_{n} parafermions. Here, we show how these models and their zero modes arise from geometric chirality in fermionic Mott insulators, focusing on n=3 where the Mott insulators are three-leg ladders. We link such ladders to Z_{3} chiral clock models by combining bosonization with general symmetry considerations. We also introduce a concrete lattice model which we show to map to the Z_{3} chiral clock model, perturbed by the Uimin-Lai-Sutherland Hamiltonian arising via superexchange. We demonstrate the presence of strong zero modes in this perturbed model by showing that correlators of clock operators at the edge remain close to their initial value for times exponentially long in the system size, even at infinite temperature.

C-reactive protein is independently associated with coronary atherosclerosis burden among octogenarians.

AIM OF THE STUDY: In contrast to the general population, individuals with primarily persistent elevation of inflammatory activity display a significant association between inflammatory biomarkers and atherosclerotic burden. In older individuals, immunosenescence upregulates the innate response and, by this way, may hypothetically favor the presence of this association. The aim of this study was to evaluate this hypothesis in healthy octogenarians. METHODS: Participants (n = 208) aged 80 years or older, asymptomatic and without medical and laboratory evidence of chronic diseases or use of anti-inflammatory treatments were included in the study. Lipid profile and plasma C-reactive protein (CRP) were measured at baseline and cardiac computed tomography was performed within 1-week interval for measuring coronary calcium score (CCS). RESULTS: The median plasma CRP was 1.9 mg/L (1.0­3.4) and 33 % of the participants had elevated CRP defined as C3 mg/L. Among those with high CRP, there was an increased frequency of high CCS (C100) as compared with their counterparts (71 vs 50 %, p = 0.001). The association between CRP and CCS persisted even after adjustment for age, sex, cardiovascular risk factors and statin therapy. The area under the receiver-operating curve for CRP was 0.606 using CCS C100 as a binary outcome. The sensitivities for CCS C100 were 40 and 74 % for the cutoff points of CRP C3 or 1 mg/L, respectively. CONCLUSION: The present study was able to confirm that in very elderly individuals, systemic inflammatory activity is independently associated with coronary atherosclerosis burden.

Towards near-term quantum simulation of materials.

Determining the ground and excited state properties of materials is considered one of the most promising applications of quantum computers. On near-term hardware, the limiting constraint on such simulations is the requisite circuit depths and qubit numbers, which currently lie well beyond near-term capabilities. Here we develop a quantum algorithm which reduces the estimated cost of material simulations. For example, we obtain a circuit depth improvement by up to 6 orders of magnitude for a Trotter layer of time-dynamics simulation in the transition-metal oxide SrVO3 compared with the best previous quantum algorithms. We achieve this by introducing a collection of connected techniques, including highly localised and physically compact representations of materials Hamiltonians in the Wannier basis, a hybrid fermion-to-qubit mapping, and an efficient circuit compiler. Combined together, these methods leverage locality of materials Hamiltonians and result in a design that generates quantum circuits with depth independent of the system's size. Although the requisite resources for the quantum simulation of materials are still beyond current hardware, our results show that realistic simulation of specific properties may be feasible without necessarily requiring fully scalable, fault-tolerant quantum computers, providing quantum algorithm design incorporates deeper understanding of the target materials and applications.

Guillain-Barré Syndrome in an Immunocompromised Patient: A Case Report.

Guillain-Barré syndrome (GBS) in post-transplant patients is a rare clinical presentation. Although in the literature this neurological condition has been mainly associated with viral infections secondary to immunosuppression, GBS should not only be suspected in patients with an acute condition. It is essential to always rule out a viral or bacterial cause, looking for the most common sources, i.e., urinary, respiratory, and gastrointestinal. The diagnosis of GBS is clinically based, and its management is based on the use of intravenous immunoglobulin (IVIG) or plasma exchange. Its timely diagnosis allows treatment to be started early, thus improving the prognosis of these patients and reducing the time of hospitalization and complications associated with it. This report shows how an interdisciplinary approach is vital in such cases, as both the precipitant and the disease must be managed to decrease the morbidity and mortality associated with this condition. It is crucial to evaluate the benefits and risks of withdrawing immunosuppressive treatment in post-transplant patients, and being able to recognize when restarting them is indicated.

Observing ground-state properties of the Fermi-Hubbard model using a scalable algorithm on a quantum computer.

The famous, yet unsolved, Fermi-Hubbard model for strongly-correlated electronic systems is a prominent target for quantum computers. However, accurately representing the Fermi-Hubbard ground state for large instances may be beyond the reach of near-term quantum hardware. Here we show experimentally that an efficient, low-depth variational quantum algorithm with few parameters can reproduce important qualitative features of medium-size instances of the Fermi-Hubbard model. We address 1 × 8 and 2 × 4 instances on 16 qubits on a superconducting quantum processor, substantially larger than previous work based on less scalable compression techniques, and going beyond the family of 1D Fermi-Hubbard instances, which are solvable classically. Consistent with predictions for the ground state, we observe the onset of the metal-insulator transition and Friedel oscillations in 1D, and antiferromagnetic order in both 1D and 2D. We use a variety of error-mitigation techniques, including symmetries of the Fermi-Hubbard model and a recently developed technique tailored to simulating fermionic systems. We also introduce a new variational optimisation algorithm based on iterative Bayesian updates of a local surrogate model.

A possible route towards dissipation-protected qubits using a multidimensional dark space and its symmetries.

Quantum systems are always subject to interactions with an environment, typically resulting in decoherence and distortion of quantum correlations. It has been recently shown that a controlled interaction with the environment may actually help to create a state, dubbed as "dark", which is immune to decoherence. To encode quantum information in the dark states, they need to span a space with a dimensionality larger than one, so different orthogonal states act as a computational basis. Here, we devise a symmetry-based conceptual framework to engineer such degenerate dark spaces (DDS), protected from decoherence by the environment. We illustrate this construction with a model protocol, inspired by the fractional quantum Hall effect, where the DDS basis is isomorphic to a set of degenerate Laughlin states. The long-time steady state of our driven-dissipative model exhibits thus all the characteristics of degenerate vacua of a unitary topological system.

Guidewire pacing safely and effectively treats bradyarrhythmias induced by rheolytic thrombectomy and precludes the need for transvenous pacing: the Scott & White experience.

Rheolytic thrombectomy (RT) is useful in certain percutaneous coronary interventions but may be associated with transient bradyarrhythmias. Clinicians have devised numerous strategies to deal with these arrhythmias apart from transvenous right ventricular pacing, some of which are described in other parts of this supplement. We report the Scott & White experience utilizing guidewire pacing to quickly and safely pace the heart in the event of bradyarrhythmia. We found this method to be safe and reliable (96.2% successful) during RT and now use this technique almost exclusively in the cardiac catheterization lab to deal with transient bradyarrhythmias during RT or due to any other cause.We also report an increased incidence of bradyarrhythmia occurring during RT when it is performed in the right coronary artery, with a trend toward an increased incidence during the clinical presentation of ST-elevation myocardial infarction.