Long-range coupling and scalable architecture for superconducting flux qubits

Constructing a fault-tolerant quantum computer is a daunting task. Given any design, it is possible to determine the maximum error rate of each type of component that can be tolerated while still permitting arbitrarily large-scale quantum computation. It is an underappreciated fact that including an appropriately designed mechanism enabling long-range qubit coupling or transport substantially increases the maximum tolerable error rates of all components. With this thought in mind, we take the superconducting flux qubit coupling mechanism described in PRB 70, 140501 (2004) and extend it to allow approximately 500 MHz coupling of square flux qubits, 50 um a side, at a distance of up to several mm. This mechanism is then used as the basis of two scalable architectures for flux qubits taking into account crosstalk and fault-tolerant considerations such as permitting a universal set of logical gates, parallelism, measurement and initialization, and data mobility.Comment: 8 pages, 11 figure

Tunneling current modulation in atomically precise graphene nanoribbon heterojunctions

Lateral heterojunctions of atomically precise graphene nanoribbons (GNRs) hold promise for applications in nanotechnology, yet their charge transport and most of the spectroscopic properties have not been investigated. Here, we synthesize a monolayer of multiple aligned heterojunctions consisting of quasi-metallic and wide-bandgap GNRs, and report characterization by scanning tunneling microscopy, angle-resolved photoemission, Raman spectroscopy, and charge transport. Comprehensive transport measurements as a function of bias and gate voltages, channel length, and temperature reveal that charge transport is dictated by tunneling through the potential barriers formed by wide-bandgap GNR segments. The current-voltage characteristics are in agreement with calculations of tunneling conductance through asymmetric barriers. We fabricate a GNR heterojunctions based sensor and demonstrate greatly improved sensitivity to adsorbates compared to graphene based sensors. This is achieved via modulation of the GNR heterojunction tunneling barriers by adsorbates

Coupling to zone center optical phonons in VSe2 enhanced by charge density waves

We investigate electron phonon coupling EPC in the charge density wave CDW phase of VSe2 by Raman spectroscopy, angle resolved photoemission spectroscopy ARPES , and ab initio calculations. Zone folding induced by the 4 4 in plane CDW phase promotes the appearance of a Raman peak at amp; 8764;170cm amp; 8722;1. The suppression of ARPES intensity in parts of the Fermi surface is also a result of CDW induced zone folding and anticrossing of the electron energy bands. The appearance of the new Raman peak is in line with the ARPES observation of a kink feature in the spectral function at the same energy. A self energy analysis yields an EPC constant of amp; 955; 0.3. Our calculations of the EPC are in excellent agreement and reveal that the kink is caused by several optical phonon branches close in energy. Our paper highlights the CDW phase as a means of inducing EPC pathways to optical phonons that directly affect its Raman spectru

Analgesic use among nursing homes residents, with and without dementia, in Poland

Agnieszka Neumann-Podczaska,1 Tomasz Nowak,2 Aleksandra Suwalska,3 Dorota Łojko,4 Roma Krzymińska-Siemaszko,2 Elżbieta Kozak-Szkopek,5 Katarzyna Wieczorowska-Tobis2 1Department of Geriatrics and Gerontology, 2Department of Palliative Medicine, Laboratory of Geriatrics, 3Department of Psychiatry, Laboratory of Neuropsychobiology, 4Department of Adult Psychiatry, Poznan University of Medical Sciences, Poznan, 5Department of Geriatrics, Medical University of Warsaw, Warsaw, Poland Abstract: Many age-associated diseases are accompanied by pain. There is no doubt that pain is underrecognized among elderly nursing home residents and the diagnosing of pain is a real challenge in subjects with dementia. The aim of the study was to characterize analgesic use among nursing home residents and to delineate the putative associations between pain management and cognitive functions of elderly persons. The study involved 392 subjects (males:females – 81:311) with a mean age of 83.6±5.9 years. The residents’ medical files in relation to diagnoses and drug consumption were analyzed, and the screening of cognitive functions was performed using the Mini-Mental State Examination (MMSE). One hundred and thirteen residents (28.8%) received some analgesics. Among them 84 (21.4%) used them routinely, 25 (6.4%) – pro re nata (PRN) and four (1.0%) – both routinely and PRN. Non-opioid analgesics were taken routinely by 53 residents, weak opioids by nine subjects, and one person was receiving strong opioids. Additionally, three individuals were taking a combination preparation of tramadol and acetaminophen. The rate of subjects who were not receiving any pain treatment was higher in residents with MMSE between 0 and 9 points than in those with MMSE between 24 and 30 points (P=0.0151). Furthermore, ten residents (9.1%) with severe dementia were treated with analgesics PRN. The results of our study point to a remarkably low use of analgesics in nursing home residents in Poland and indicate a need to introduce pain evaluation and monitoring of drug treatment appropriateness as a standard procedure in the geriatric assessment in nursing homes. Keywords: pain, the elderly, analgesics, dementia, Mini-Mental State Examination, multimorbidit

Development and external validation of a clinical prediction model for MRSA carriage at hospital admission in Southeast Lower Saxony, Germany.

In countries with low endemic Methicillin-resistant Staphylococcus aureus (MRSA) prevalence, identification of risk groups at hospital admission is considered more cost-effective than universal MRSA screening. Predictive statistical models support the selection of suitable stratification factors for effective screening programs. Currently, there are no universal guidelines in Germany for MRSA screening. Instead, a list of criteria is available from the Commission for Hospital Hygiene and Infection Prevention (KRINKO) based on which local strategies should be adopted. We developed and externally validated a model for individual prediction of MRSA carriage at hospital admission in the region of Southeast Lower Saxony based on two prospective studies with universal screening in Braunschweig (n = 2065) and Wolfsburg (n = 461). Logistic regression was used for model development. The final model (simplified to an unweighted score) included history of MRSA carriage, care dependency and cancer treatment. In the external validation dataset, the score showed a sensitivity of 78.4% (95% CI: 64.7-88.7%), and a specificity of 70.3% (95% CI: 65.0-75.2%). Of all admitted patients, 25.4% had to be screened if the score was applied. A model based on KRINKO criteria showed similar sensitivity but lower specificity, leading to a considerably higher proportion of patients to be screened (49.5%)

Fluctuation-dissipation in thermoelectric sensors

Tran NAM, Dutt AS, Pulumati NB, et al. Fluctuation-dissipation in thermoelectric sensors. EPL (Europhysics Letters) . 2023;141(1): 26002.Thermoelectric materials exhibit correlated transport of charge and heat. The Johnson-Nyquist noise formula 4kBTR for the spectral density of voltage fluctuations accounts for fluctuations associated solely with Ohmic dissipation. Applying the fluctuation-dissipation theorem, we generalize the Johnson-Nyquist formula for thermoelectrics, finding an enhanced voltage fluctuation spectral density 4kBTR(1 + ZDT ) at frequencies below a thermal cut-off fre-quency fT, where ZDT is the dimensionless thermoelectric device figure of merit. The origin of the enhancement in voltage noise is thermoelectric coupling of temperature fluctuations. We use a wideband (fT similar to 1 kHz), integrated thermoelectric micro-device to experimentally confirm our findings. Measuring the ZDT enhanced voltage noise, we experimentally resolve temperature fluc-tuations with a root mean square amplitude of 0.8 mu K Hz-1/2 at a mean temperature of 295 K. We find that thermoelectric devices can be used for thermometry with sufficient resolution to measure the fundamental temperature fluctuations described by the fluctuation-dissipation theorem