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A requirement for quantum information processors is the in situ tunability of the tunnel rates and the exchange interaction energy within the device. The large energy level separation for atom qubits in silicon is well suited for qubit operation but limits device tunability using in-plane gate architectures, requiring vertically separated top-gates to control tunnelling within the device. In this paper, we address control of the simplest tunnelling device in Si:P, the tunnel junction. Here we demonstrate that we can tune its conductance by using a vertically separated top-gate aligned with ±5 nm precision to the junction. We show that a monolithic 3D epitaxial top-gate increases the capacitive coupling by a factor of 3 compared to in-plane gates, resulting in a tunnel barrier height tunability of 0–186 meV. By combining multiple gated junctions in series we extend our monolithic 3D gating technology to implement nanoscale logic circuits including AND and OR gates.

Universal quantum computing requires fast single- and two-qubit gates with individual qubit addressability to minimize decoherence errors during processor operation. Electron spin qubits using individual phosphorus donor atoms in silicon have demonstrated long coherence times with high fidelities, providing an attractive platform for scalable quantum computing. While individual qubit addressability has been demonstrated by controlling the hyperfine interaction between the electron and nuclear wave function in a global magnetic field, the small hyperfine Stark coefficient of 0.34 MHz/MV m–1achieved to date has limited the speed of single quantum gates to ∼42 μs to avoid rotating neighboring qubits due to power broadening from the antenna. The use of molecular 2P qubits with more than one donor atom has not only demonstrated fast (0.8 ns) two-qubit SWAPgates and long spin relaxation times of ∼30 s but provides an alternate way to achieve high selectivity of the qubit resonance frequency. Here, we show in two different devices that by placing the donors with comparable interatomic spacings (∼0.8 nm) but along different crystallographic axes, either the [110] or [310] orientations using STM lithography, we can engineer the hyperfine Stark shift from 1 MHz/MV m–1to 11.2 MHz/MV m–1, respectively, a factor of 10 difference. NEMO atomistic calculations show that larger hyperfine Stark coefficients of up to ∼70 MHz/MV m–1can be achieved within 2P molecules by placing the donors ≥5 nm apart. When combined with Gaussian pulse shaping, we show that fast single qubit gates with 2π rotation times of 10 ns and ∼99% fidelity single qubit operations are feasible without affecting neighboring qubits. By increasing the single qubit gate time to ∼550 ns, two orders of magnitude faster than previously measured, our simulations confirm that >99.99% single qubit control fidelities are achievable.

The anticardiolipin (aCL) and antibeta2-glycoprotein I (a2GPI) antibodies are used to diagnosis antiphospholipid syndrome. It would be possible to use two or more methods to improve the diagnostic sensitivity of aCL and a2GPI. In this study, we investigated the laboratory performance of a new chemiluminescent assay and explored whether the combined results of aCL and a2GPI measured by two different methods predict thrombotic risk better. The cut-off values were assessed with 99 healthy controls. The coefficient of variations was determined using control materials. Using the plasma of 109 patients, AcuStar chemiluminescent assay and QUANTA Lite ELISA were carried out according to the manufacturers’ instructions. The AcuStar cut-off points were 13.5Uml for aCL IgG, 19.1Uml for aCL IgM, 16.3Uml for a2GPI IgG and 12.6Uml for a2GPI IgM. Total coefficient of variations ranged from 4.6 to 8.8. For both aCL and a2GPI, the AcuStar odds ratio for thrombosis prediction was higher than that of QUANTA Lite. When the results for both AcuStar and QUANTA Lite are positive, the odds ratios of aCL and a2GPI were higher than that interpreted by a single positive result each. The new automated chemiluminescent assay exhibited good precision, concordance rate, and clinical performance. The combined results of aCL and a2GPI as measured by two different methods are expected to increase the prediction power for thrombosis.

Since the retreat of the workplace system, Chinese cities have been presented with the important challenge of refurbishing local administrative systems at the sub-district level while meeting the emerging needs of new urban spaces. Building on new institutionalism concepts such as conversion and layering, this study examines conditions in Shanghai to ascertain what has made it a strong administrative city. The study discusses the development of Shanghai’s current local governance structure in terms of historical legacy, formal structure, and informal practices (i.e., two-tiered government and three-tiered management). This study also researches the complex state task of strengthening sub-district governance (so-called “community construction”) in urban China. The results of this study offer theoretical implications for institutional change and continuity related to these matters, thereby indicating that increased attention should be given to the agency-side explanation of endogenous institutional changes in the Chinese polity.