Numerical simulation of quantum systems is crucial to further our understanding of natural phenomena. Many systems of key interest and importance, in areas such as superconducting materials and quantum chemistry, are thought to be described by models which we cannot solve with sufficient accuracy, neither analytically nor numerically with classical computers. Using a quantum computer to simulate such quantum systems has been viewed as a key application of quantum computation from the very beginning of the field in the 1980s. Moreover, useful results beyond the reach of classical computation are expected to be accessible with fewer than a hundred qubits, making quantum simulation potentially one of the earliest practical applications of quantum computers. In this paper we survey the theoretical and experimental development of quantum simulation using quantum computers, from the first ideas to the intense research efforts currently underway.

Studies by Raman microprobe spectroscopy have shown that the black ink defining each feature on the controversial Vinland Map consists of carbon that overlays a yellow line containing anatase. This material was not detected elsewhere on the map. Since anatase has not been found on medieval artifacts, and such yellow lines are only naturally produced by iron gallotannate inks, a modern (post 1923) origin for the Vinland Map is strongly indicated. The ink of the Tartar Relation is different and probably consists of an iron gallotannate mixed with a small proportion of carbon. The rubrication is established to be vermilion.

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Efficient generation of cluster states is crucial for engineering large-scale measurement-based quantum computers. Hybrid matter-optical systems offer a robust, scalable path to this goal. Such systems have an ancilla which acts as a bus connecting the qubits. We show that by generating the cluster in smaller sections of interlocking bricks, reusing one ancilla per brick, the cluster can be produced with maximal efficiency, requiring fewer than half the operations compared with no bus reuse. By reducing the time required to prepare sections of the cluster, bus reuse more than doubles the size of the computational workspace that can be used before decoherence effects dominate. A row of buses in parallel provides fully scalable cluster-state generation requiring only 20 controlled-PHASE gates per bus use.

The Lindisfarne Gospels (Cotton MS Nero D iv, ca. 715 AD) and two nearly contemporary manuscripts (Royal MS 1B vii and Add. MS 40618) held in the British Library have been analysed in detail by Raman microscopy in order to establish the palette of each. The blue pigment used on the Lindisfarne Gospels is shown not to be lazurite, as concluded in 1960 by visual examination of known pigments and those on the Gospels, but exclusively indigo. Of the Anglo-Saxon and Insular manuscripts studied so far by Raman microscopy, the earliest found to include lazurite in its palette is Add. MS 40618, not on its still extant original miniature of ca. 756 AD, but on later additions of ca. 920 AD. The Insular triumvirate palette, which had been assumed to consist of orpiment, red lead and verdigris, was found also to include red ochre and vergaut (indigo admixed with orpiment) but not necessarily verdigris. The palettes of the manuscripts studied, as specified in existing literary sources, are not reliable, and careful in situ scientific analysis of the pigments present is essential to establish the identity of the latter and of any decomposition products present.