realization of a universal quantum computer [2]. In this project, we undertake the task of implementing an extensible wiring method for the operation of a quantum processor based on solid-state devices, e.g., superconducting qubits [3][4][5]. Possible experimental solutions based on wafer bonding techniques [6-9] or coaxial through-silicon vias [10] as well as theoretical proposals [1,11] have recently addressed the wiring issue, highlighting it as a priority for quantum computing.Building a universal quantum computer [12-17] will make it possible to execute quantum algorithms [18], which would have profound implications on scientific research and society. For a quantum computer to be competitive with the most advanced classical computer, it is widely believed that the qubit operations will require error rates on the order of 10 −15 or less. Achieving such error rates is only possible by means of quantum error correction (QEC) algorithms [13,15,19], which allow for arXiv:1606.00063v1 [quant-ph]

N00N states -maximally path-entangled states of N photons -exhibit spatial interference patterns sharper than any classical interference pattern. This is known as super-resolution. However, even with perfectly efficient number-resolving detectors, the detection efficiency of all previously demonstrated methods to measure such interference decreases exponentially with the number of photons in the N00N state, often leading to the conclusion that N00N states are unsuitable for spatial measurements. Here, we create spatial super-resolution fringes with two-, three-, and fourphoton N00N states, and demonstrate a scalable implementation of the so-called "optical centroid measurement" which provides an in-principle perfect detection efficiency. Moreover, we compare the N00N-state interference to the corresponding classical super-resolution interference. Although both provide the same increase in spatial frequency, the visibility of the classical fringes decreases exponentially with the number of detected photons, while the visibility of our experimentally measured N00N-state super-resolution fringes remains approximately constant with N. Our implementation of the optical centroid measurement is a scalable method to measure high photon-number quantum interference, an essential step forward for quantum-enhanced measurements, overcoming what was believed to be a fundamental challenge to quantum metrology.Many essential techniques in modern science and technology, from precise position sensing to high-resolution imaging to nanolithography, rely on the creation and detection of the finest possible spatial interference fringes using light. Classically, all such measurements face a fundamental barrier related to the "diffraction limit," which is determined by the wavelength of the light [1], but quantum entanglement can be used to surpass this limit by making the spatial interference fringes sharper (a result referred to as super-resolution) [2,3]. In particular, the N-photon entangled "N00N" state can display an interference pattern N times finer than that of classical light [4,5]. However, N00N states suffer from a weakness that has made their advantage controversial: the probability of all N photons arriving at the same place, and thus the detection efficiency, decreases exponentially with N [6,7]. Here we implement the optical centroid measurement (OCM) proposed by Tsang [8] to completely overcome this problem. A proof-of-principle experiment confirming the underlying concept of the OCM was recently performed [9], but, being limited to only two photons and two 'movable' detectors, it could not probe the scaling properties nor demonstrate the efficiency gain of the OCM. In our experiment, using an array of 11 fixed detectors, we measure two-, three-, and four-photon spatial fringes, and find that their visibility does not degrade with the number of entangled photons, clearly displaying the enhanced efficiency and scalability of the OCM. The visibility of an unentangled OCM, on the other hand, decays exponentially. In doing...

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N00N states -maximally path-entangled states of N photons -exhibit spatial interference patterns sharper than any classical interference pattern. This is known as super-resolution. However, even with perfectly efficient number-resolving detectors, the detection efficiency of all previously demonstrated methods to measure such interference decreases exponentially with the number of photons in the N00N state, often leading to the conclusion that N00N states are unsuitable for spatial measurements. Here, we create spatial super-resolution fringes with two-, three-, and fourphoton N00N states, and demonstrate a scalable implementation of the so-called "optical centroid measurement" which provides an in-principle perfect detection efficiency. Moreover, we compare the N00N-state interference to the corresponding classical super-resolution interference. Although both provide the same increase in spatial frequency, the visibility of the classical fringes decreases exponentially with the number of detected photons, while the visibility of our experimentally measured N00N-state super-resolution fringes remains approximately constant with N. Our implementation of the optical centroid measurement is a scalable method to measure high photon-number quantum interference, an essential step forward for quantum-enhanced measurements, overcoming what was believed to be a fundamental challenge to quantum metrology.

Incidence and prevalence are key epidemiological determinants characterizing the quantum of a disease. We compared incidence and prevalence estimates derived automatically from the first ever online, essentially real-time, healthcare analytics platform—Livingstone—against findings from comparable peer-reviewed studies in order to validate the descriptive epidemiology module. The source of routine NHS data for Livingstone was the Clinical Practice Research Datalink (CPRD). After applying a general search strategy looking for any disease or condition, 76 relevant studies were first retrieved, of which 10 met pre-specified inclusion and exclusion criteria. Findings reported in these studies were compared with estimates produced automatically by Livingstone. The published reports described elements of the epidemiology of 14 diseases or conditions. Lin’s concordance correlation coefficient (CCC) was used to evaluate the concordance between findings from Livingstone and those detailed in the published studies. The concordance of incidence values in the final year reported by each study versus Livingstone was 0.96 (95% CI: 0.89–0.98), whilst for all annual incidence values the concordance was 0.93 (0.91–0.94). For prevalence, concordance for the final annual prevalence reported in each study versus Livingstone was 1.00 (0.99–1.00) and for all reported annual prevalence values, the concordance was 0.93 (0.90–0.95). The concordance between Livingstone and the latest published findings was near perfect for prevalence and substantial for incidence. For the first time, it is now possible to automatically generate reliable descriptive epidemiology from routine health records, and in near-real time. Livingstone provides the first mechanism to rapidly generate standardised, descriptive epidemiology for all clinical events from real world data.