An Architecture for Improved Surface Code Connectivity in Neutral Atoms

In order to achieve error rates necessary for advantageous quantum algorithms, Quantum Error Correction (QEC) will need to be employed, improving logical qubit fidelity beyond what can be achieved physically. As today's devices begin to scale, co-designing architectures for QEC with the underlying hardware will be necessary to reduce the daunting overheads and accelerate the realization of practical quantum computing. In this work, we focus on logical computation in QEC. We address quantum computers made from neutral atom arrays to design a surface code architecture that translates the hardware's higher physical connectivity into a higher logical connectivity. We propose groups of interleaved logical qubits, gaining all-to-all connectivity within the group via efficient transversal CNOT gates. Compared to standard lattice surgery operations, this reduces both the overall qubit footprint and execution time, lowering the spacetime overhead needed for small-scale QEC circuits. We also explore the architecture's scalability. We look at using physical atom movement schemes and propose interleaved lattice surgery which allows an all-to-all connectivity between qubits in adjacent interleaved groups, creating a higher connectivity routing space for large-scale circuits. Using numerical simulations, we evaluate the total routing time of interleaved lattice surgery and atom movement for various circuit sizes. We identify a cross-over point defining intermediate-scale circuits where atom movement is best and large-scale circuits where interleaved lattice surgery is best. We use this to motivate a hybrid approach as devices continue to scale, with the choice of operation depending on the routing distance

VarSaw: Application-tailored Measurement Error Mitigation for Variational Quantum Algorithms

For potential quantum advantage, Variational Quantum Algorithms (VQAs) need high accuracy beyond the capability of today's NISQ devices, and thus will benefit from error mitigation. In this work we are interested in mitigating measurement errors which occur during qubit measurements after circuit execution and tend to be the most error-prone operations, especially detrimental to VQAs. Prior work, JigSaw, has shown that measuring only small subsets of circuit qubits at a time and collecting results across all such subset circuits can reduce measurement errors. Then, running the entire (global) original circuit and extracting the qubit-qubit measurement correlations can be used in conjunction with the subsets to construct a high-fidelity output distribution of the original circuit. Unfortunately, the execution cost of JigSaw scales polynomially in the number of qubits in the circuit, and when compounded by the number of circuits and iterations in VQAs, the resulting execution cost quickly turns insurmountable. To combat this, we propose VarSaw, which improves JigSaw in an application-tailored manner, by identifying considerable redundancy in the JigSaw approach for VQAs: spatial redundancy across subsets from different VQA circuits and temporal redundancy across globals from different VQA iterations. VarSaw then eliminates these forms of redundancy by commuting the subset circuits and selectively executing the global circuits, reducing computational cost (in terms of the number of circuits executed) over naive JigSaw for VQA by 25x on average and up to 1000x, for the same VQA accuracy. Further, it can recover, on average, 45% of the infidelity from measurement errors in the noisy VQA baseline. Finally, it improves fidelity by 55%, on average, over JigSaw for a fixed computational budget. VarSaw can be accessed here: https://github.com/siddharthdangwal/VarSaw.Comment: Appears at the International Conference on Architectural Support for Programming Languages and Operating Systems (ASPLOS) 2024. First two authors contributed equall

Unified Angular Momentum of Dyons

Unified quaternionic angular momentum for the fields of dyons and gravito-dyons has been developed and the commutation relations for dynamical variables are obtained in compact and consistent manner. Demonstrating the quaternion forms of unified fields of dyons (electromagnetic fields) and gravito-dyons (gravito-Heavisidian fields of linear gravity), corresponding quantum equations are reformulated in compact, simpler and manifestly covariant way

LANDSLIDE HAZARD ZONATION IN AND AROUND KEDARNATH REGION AND ITS VALIDATION BASED ON REAL TIME KEDARNATH DISASTER USING GEOSPATIAL TECHNIQUES

Landslides are one of the frequently happening disasters in this hilly state of Uttarakhand which accounts to the loss of lives and property every year especially during the rainy season which lead to affect the families. With the development of satellite observation technique, advanced data analysis tool and new modeling techniques landslide hazard zonation map can be prepared.In the present study, Landslide Hazard Zonation (LHZ) for Kedarnath to Augustmuni region of Rudraprayag district of Uttarakhand state was carried out using Remote Sensing and GIS technique. For the preparation of LHZ map, year 2010 high resolution satellite data have been used. After preprocessing of the data various thematic layers are prepared in GIS environment. The weighted-rating system technique were used for the LHZ map showing the five zones, namely “very low hazard”, “low hazard”, “moderate hazard”, “high hazard” and “very high hazard” . This map has been validated after the tragedy of Kedarnath in Uttarakhand, Total no. of 224 Landslides has been marked from Kedarnath to Augustmuni region just after the kedarnath tragedy in year 2013. When this landslides thematic layer is overlaid on LHZ, the study shows that approximately 50% landslides was there where in LHZ map high and very high hazard zones have been identified. After the tragedy our team workers have gone to the field, with the help of DGPS around 40 ground control points have been taken to validate our result. So by using this geospatial technique around 50% people’s life can be saved.</p

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Not AvailablePigeonpea sterility mosaic emaraviruses (PPSMVs) cause sterility mosaic disease in pigeonpea which significantly reduce the crop yield. Currently there are no effective management strategies available for the control of these emaraviruses or their vector eriophyid mites. Here, for the first time, we demonstrate double stranded RNA based control of PPSMV in an open field experiment. Three genes of PPSMV, namely, the RNA dependent RNA polymerase, nucleo-capsid protein and movement protein were targeted by dsRNA-based strategy. DsRNAs for these genes were successfully produced in vitro and exogenously applied on pigeonpea plants in the field providing protection against PPSMV. Of these, the dsRNAs targeting RNA dependent RNA polymerase and movement protein gave relatively better protection when compared to the dsRNAs targeting nucleo-capsid protein. This is the first demonstration of dsRNA-mediated protection against a negative sense plant RNA virus.Not Availabl

Influence of the Microstructure of Gold-Zirconia Yolk-Shell Catalysts on the CO Oxidation Activity

The gold−zirconia yolk−shell system is an interesting catalyst for CO oxidation. The size distribution of the gold nanoparticles is very narrow, and they are well separated from each other also after treatment at high temperature, which is due to their encapsulation in crystalline zirconia hollow spheres. Because this allows thermal and chemical treatment without affecting the size distribution, different defect structures of the gold nanoparticles can be induced, and the effect on catalytic activity can be investigated. Line profile analysis of the powder diffraction data based on the whole powder pattern modeling approach was used to determine the domain size distribution and lattice defects present in this two-phase system. The influence of different diffractometer setups on the results of the line profile analysis was also investigated. Variation of the chemical and thermal treatment procedures allowed altering the microstructure of the system. The resulting catalysts showed substantial variation in the activity for CO oxidation. Lower dislocation densities and less stacking faults result in decreased catalytic activity. These contributions to activity could be studied without any superimposed size effect due to the constant gold particle sizes

COMPARATIVE STUDY OF VARIOUS TECHNIQUES FOR ENVIRONMENTAL RADON, THORON AND PROGENY MEASUREMENTS

Long-term average concentrations of radon, thoron and progeny were measured in normal and high background radiation areas in India using different techniques. Radon, thoron and progeny concentrations were measured using Raduet, Pin-Hole dosimeter, deposition-based CR-39 and deposition-based direct radon/thoron progeny sensor (DRPS/DTPS) detector system. All these techniques were used at a same time inside an individual dwelling. Radon concentration was recorded higher than thoron concen- tration in Garhwal Homes (NBRA) while thoron concentration was found relatively higher in the houses of Chhatarpur area (HBRA) in Odisha, India. The values measured with the CR-39 detector-based technique were found comparable with the values measured with the LR-115 detector-based technique. The comparisons of results using various techniques and their usefulness in radiation measurements are discussed in detail

Size-Controlled Synthesis and Microstructure Investigation of Co₃O₄ Nanoparticles for Low Temperature CO Oxidation

Noble-metal-free functional oxides are active catalysts for CO oxidation at low temperatures. Spinel-type cobalt oxide (Co3O4) nanoparticles can be easily synthesized by impregnation of activated carbon with concentrated cobalt nitrate and successive carbon burn off. Mean size and particle size distribution can be tuned by adding small amounts of silica to the carbon precursor, as witnessed by whole powder pattern modeling of the X-ray powder diffraction data. The catalytic tests performed after silica removal show a significant influence of the mean domain size and of size distribution on the CO oxidation activity of the individual Co3O4 specimens, whereas defects play a less important role in the present case