## A Potentially Realizable Quantum Computer in Science, Volume 261, Number 5128, September 17, 1993, pp. 1569-1571

New York: American Association for the Advancement of Science, 1993. 1st Edition. FIRST EDITION IN ORIGINAL PICTORIAL WRAPS OF THE 1st PAPER TO ?PROPOSE THE FIRST TECHNOLOGICALLY FEASIBLE DESIGN FOR A QUANTUM COMPUTER? (Wikipedia). PRISTINE condition with no mailing label.

?Quantum computing studies theoretical computation systems (quantum computers) that make direct use of quantum-mechanical phenomena, such as superposition and entanglement, to perform operations on data? (Gershenfeld, ?Quantum Computing with Molecules? in Scientific American, June 1988). ?Quantum computers are different from binary digital electronic computers based on transistors. Whereas common digital computing requires that the data be encoded into binary digits (bits), each of which is always in one of two definite states (0 or 1), quantum computation uses quantum bits, which can be in superpositions of states? (Wikipedia).

Seth Lloyd, a self-proclaimed ?quantum mechanic?, is a professor of mechanical engineering and physics at MIT. His ?potentially realizable? quantum computer is described in this paper as ?arrays of weakly coupled quantum systems. Computation is effected by a sequence of electromagnetic pulses that induce transitions between locally defined quantum states? in a crystal lattice? (Van Loocke, The Physical Nature of Consciousness, 41).

This means that in Lloyd?s computer architecture, every ?quit?, or gate, does not need to be addressed individually. Lloyd?s architecture necessitates ?only a few control quits are needed, while the quantum information is stored in a chain of quits that consists of repeated units ABC of only three distinguishable physical qubits. Each group of three physical quits stores one logical quit. Logical operations can be broken down into operations that act on all A, B or C physical quits. It was shown that this architecture is universal, i.e., it can efficiently run all algorithms that are efficient on a network quantum computer? (Stolze, Quantum Computing, 143).

Lloyd argues that ?operated with frequent error correction, such a system functions as a parallel digital computer. Operated in a quantum-mechanically coherent manner, such a device functions as a general purpose quantum-mechanical micro-manipulator, capable of both creating any desired quantum state of the array and transforming that state in any desired way? (Lloyd, 1993, p. 1569).

In a 1996 paper that we offer separately, Lloyd would go on to prove that Feynman?s 1982 conjecture that quantum computers can be programmed to simulate any local quantum system is correct. In the 1996 paper, Lloyd ?proved that a universal quantum simulator is possible by showing that a quantum computer can be programmed to simulate any local quantum system efficiently? (History of Science: The Wenner Collection; Wikipedia). Item #1317

CONDITION & DETAILS: New York: American Association for the Advancement of Science. 8vo. Complete. Pristine inside and out.

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