Read-only-memory-based quantum computation: Experimental explorations using nuclear magnetic resonance and future prospects

Read-only-memory-based (ROM-based) quantum computation (QC) is an alternative to oracle-based QC. It has the advantages of being less magical, and being more suited to implementing space-efficient computation (i.e., computation using the minimum number of writable qubits). Here we consider a number of small (one- and two-qubit) quantum algorithms illustrating different aspects of ROM-based QC. They are: (a) a one-qubit algorithm to solve the Deutsch problem; (b) a one-qubit binary multiplication algorithm; (c) a two-qubit controlled binary multiplication algorithm; and (d) a two-qubit ROM-based version of the Deutsch-Jozsa algorithm. For each algorithm we present experimental verification using nuclear magnetic resonance ensemble QC. The average fidelities for the implementation were in the ranges 0.9-0.97 for the one-qubit algorithms, and 0.84-0.94 for the two-qubit algorithms. We conclude with a discussion of future prospects for ROM-based quantum computation. We propose a four-qubit algorithm, using Grover's iterate, for solving a miniature real-world problem relating to the lengths of paths in a network.

Did they read Marx? Marx reception and social democratic party members in imperial Germany, 1890-1914

Did rank-and-file members of the German Social Democratic party before 1914 bother to read Marx? A number of studies of borrowing from trade union and other workers' libraries since the 1970s have indicated that workers who read Marx were rare, although this does not mean that workers' reading habits were not influenced by socialist ideas. However, for a broader understanding of the reception of Marx's writings among rank-and-file German socialists, it is necessary to consider not only books, but the pamphlet literature produced by the SPD in huge quantities, serialisations and other treatments in the party press, and oral communication. When the full range of sources is considered, the extent of the reception of Marx's writings, albeit often in very simplified forms, can be more fully appreciated.