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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. Correlated errors coming from leakage out of the computational subspace are an obstacle to fault-tolerant superconducting circuits. Here, the authors use a multi-level reset protocol to improve the performances of a bit-flip error correcting code by reducing the magnitude of correlations.

A promising approach to study condensed-matter systems is to simulate them on an engineered quantum platform 1 – 4 . However, the accuracy needed to outperform classical methods has not been achieved so far. Here, using 18 superconducting qubits, we provide an experimental blueprint for an accurate condensed-matter simulator and demonstrate how to investigate fundamental electronic properties. We benchmark the underlying method by reconstructing the single-particle band structure of a one-dimensional wire. We demonstrate nearly complete mitigation of decoherence and readout errors, and measure the energy eigenvalues of this wire with an error of approximately 0.01 rad, whereas typical energy scales are of the order of 1 rad. Insight into the fidelity of this algorithm is gained by highlighting the robust properties of a Fourier transform, including the ability to resolve eigenenergies with a statistical uncertainty of 10 −4 rad. We also synthesize magnetic flux and disordered local potentials, which are two key tenets of a condensed-matter system. When sweeping the magnetic flux we observe avoided level crossings in the spectrum, providing a detailed fingerprint of the spatial distribution of local disorder. By combining these methods we reconstruct electronic properties of the eigenstates, observing persistent currents and a strong suppression of conductance with added disorder. Our work describes an accurate method for quantum simulation 5 , 6 and paves the way to study new quantum materials with superconducting qubits. As a blueprint for high-precision quantum simulation, an 18-qubit algorithm that consists of more than 1,400 two-qubit gates is demonstrated, and reconstructs the energy eigenvalues of the simulated one-dimensional wire to a precision of 1 per cent.

Background: On the basis of our previous study, which examined the nonlinear relationship between visceral fat area (VFA) and percent regional fat mass in the trunk, we hypothesise the presence of some storage capacity of subcutaneous fat. This study aimed to examine the storage capacity of subcutaneous fat on the basis of subcutaneous fat area (SFA) and VFA in 791 Japanese adult males and 563 females. Methods: Regression analyses by using SFA as a dependent variable and VFA as an independent variable were performed for each group classified by visceral fat obesity (VO): VO (VFA ⩾100 cm 2 ) and the no-VO (NVO) groups. To statistically identify an optimal critical point for subcutaneous fat accumulation, we changed the cutoff point for the VO group from 50–150 cm 2 in 10-cm 2 increments and confirmed the significance of the correlation between SFA and VFA for each obesity group, the statistical difference in correlations between NVO and VO groups, and the goodness of fit for the two regression lines using the standard error of estimation values. These analyses were conducted for each sex and age (<65 and ⩾65 years) group. Results: The critical point for subcutaneous fat accumulation appears at the following cutoff points of VFA: 130 cm 2 in <65-year-old males, 110 cm 2 in ⩾65-year-old males and 100 cm 2 in both female groups. Conclusions: These results suggest the presence of some storage capacity of subcutaneous fat. As a further application, these findings may serve to improve the risk assessment of obesity-related diseases.

Transition metal dichalcogenides 2H-TaS2 and 2H-TaSe2 show charge density wave (CDW) state and superconductivity. It has been reported that elemental substitution of chalcogenide suppresses the CDW and enhances superconductivity. However, how the CDW order is suppressed by the substitution has not been clarified yet. To clarify this, we performed real space observation of the CDW state in the commensurate phase of 2H-TaS1.8Se0.2 by scanning tunneling microscopy. The existence of domains separated by walls at which the phase of the CDW shifts was observed. The change in the electronic state on the domain boundaries in 2H-TaS1.8Se0.2 was not as drastic as that in 1T-FexTa1-xS2.

Single crystal of 2H-TaS2 was synthesized with flux method using the flux in which alkali metal ions were included. Analysis of the composition and the structure by EDX measurements and X-Ray diffraction showed that the hydrates of potassium ion were intercalated in 2H-TaS2 synthesized with NaCl/KCl flux. The local intercalation was confirmed by the observation of the superstructures with the period of 2a0 × 2a0 or √3a0 × √3a0 by scanning tunnelling microscopy measurements.

Objectives: L-ornithine has an important role in ammonia metabolism via the urea cycle. This study aimed to examine the effect of L-ornithine hydrochloride ingestion on performance during incremental exhaustive ergometer bicycle exercise and ammonia metabolism during and after exercise. Subjects/Methods: In all, 14 healthy young adults (age: 22.2±1.0 years, height: 173.5±4.6 cm, body mass: 72.5±12.5 kg) who trained regularly conducted incremental exhaustive ergometer bicycle exercises after -ornithine hydrochloride supplementation (0.1 g/kg, body mass) and placebo conditions with a cross-over design. The exercise time (sec) of the incremental ergometer exercise, exercise intensity at exhaustion (watt), maximal oxygen uptake (ml per kg per min), maximal heart rate (beats per min) and the following serum parameters were measured before ingestion, 1 h after ingestion, just after exhaustion and 15 min after exhaustion: ornithine, ammonia, urea, lactic acid and glutamate. All indices on maximal aerobic capacity showed insignificant differences between both the conditions. Results: Plasma ammonia concentrations just after exhaustion and at 15 min after exhaustion were significantly more with ornithine ingestion than with placebo. Plasma glutamate concentrations were significantly higher after exhaustion with ornithine ingestion than with placebo. Conclusions: It was suggested that, although the ingestion of L-ornithine hydrochloride before the exercise cannot be expected to improve performance, it does increase the ability to buffer ammonia, both during and after exercise.

1T-TaS2 has been known to undergo Mott transition from nearly commensurate charge density wave (CDW) state to commensurate CDW state at about 200 K. Recently, Fe doping was found to suppress the Mott transition and induce superconductivity. In this study, we report on the scanning tunneling microscopy (STM) and spectroscopy (STS) study on Fe doped 1T-TaS2 with different Fe concentration. STM observations reveal that the CDW superlattice becomes irregular as increasing Fe concentration. STS measurements uncover the spatial change in the local density of state (LDOS). We find two types of David-star: one has symmetric LDOS with respect to Fermi energy, and the other has asymmetric one. We identify that the asymmetric spectrum is due to an Fe dopant.

SARS-CoV-2 infection can lead to potentiation of oncological diseases, including due to virus interaction with cancer stem cells (CSC). The aim of this paper is to analyze approaches and treatments that may be effective against both coronavirus infection and cancer at the same time. Lung cancer material was analyzed with pathomorphological and immunohistochemical methods using CSC and SARS-CoV-2 markers. Co-localization of cancer stem cells zones and coronavirus protein expression in tissues of cancer patients after coronavirus infection was demonstrated. It was shown that photodynamic therapy with polycationic photosensitizes can be effective against both coronavirus infection and cancer at the same time. Photodynamic therapy of SARS-CoV-2-affected lung tissue, especially with polycationic photosensitizers, can simultaneously suppress the virus and tumor growth.

We examined a concentration of Bi defects in layered BiCh2 based superconductors LnO1-xFxBiCh2 (Ln = La, Ce, Nd Ch = S, Se). These materials show superconductivity by electron carrier doping into BiCh2 layer. Since Bi defects affect the carrier concentration directly, an examination of the concentration is important to evaluate an actual carrier concentration. In this paper, the concentration of Bi defects on the BiCh2 layers in BiCh2 based superconductors was evaluated by scanning tunneling microscopy measurements in real space. We found the samples with BiSe2 layers have less Bi defects than those with BiS2 layers. Furthermore, the concentration of Bi defects was found to be almost constant regardless of F concentration and Ln ion.

Reports have detailed the increasing use of spinal instrumentation in the treatment of pyogenic vertebral osteomyelitis, with the aims of achieving a lower pseudoarthrosis rate and restoring spinal alignment. However, controversy remains over the use of instrumentation in the presence of active infection because of concerns about increased bacterial adherence and biofilm formation on the metallic implant surface. Fourteen consecutive patients were followed who were diagnosed as having pyogenic vertebral osteomyelitis and underwent surgery with spinal instrumentation with iodine-containing surfaces that could be directly supported to existing titanium implants. Bone–cage interfaces and implant-related complications after surgery were evaluated. The white blood cell (WBC) count and C-reactive protein (CRP) level were analyzed during the follow-up period. To confirm the influence of iodine release from the implant, thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), and free thyroxine (FT4) were also examined. The infection subsided in all 14 patients. Both WBC counts and CRP levels returned to normal ranges by the final follow-up. One patient showed a lucent area around the screw and two patients showed lucencies inside the cage. However, no cage dislocations, cage migrations, or screw pull-outs were noted, and all patients’ FT3, FT4, and TSH levels were within normal ranges during the follow-up period. We demonstrated the efficacy of iodine-supported titanium implants in the management of pyogenic vertebral osteomyelitis. No cytotoxicity or adverse effects were noted in this series.