Universal Quantum Simulators in Science, Volume 273, Number 5278, 23 August 1996, pp. 1073-1078

New York: American Association for the Advancement of Science, 1996. 1st Edition. FIRST EDITION IN ORIGINAL WRAPS OF THE FIRST PROOF "THAT UNIVERSAL COMPUTERS CAN BE BUILT FROM QUANTUM MECHANICAL SYSTEMS" (Stolz, Quantum Computing, 129). In 1982 Feynman conjectured that quantum computers can be programmed to simulate any local quantum system. In this paper, Seth Lloyd proves that Feynman was correct. He "prove[s] 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).

"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 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). In that 1993 paper (which we offer separately) 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).

In this 1996 paper, Lloyd goes further. Feynman had essentially asked whether implicit exponential explosion might be bypassed by "having one quantum system simulate another directly so that the states of the simulator obey the same equations of motion as the states of the simulated system... [In 1996, Lloyd shows] that a variety of quantum systems, including quantum computers, can be ‘programmed' to simulate the behavior of arbitrary quantum systems whose dynamics are determined by local interactions. The programming is accomplished by inducing interactions between the variables of the simulator that imitate the interactions between the variables of the system to be simulated. In effect, the dynamics of the properly programmed simulator and the dynamics of the system to be simulated are one and the same to within any desired accuracy" (Lloyd, 1996, p. 1073). CONDITION & DETAILS: New York: American Association for the Advancement of Science. 8vo. Complete. Very light spotting on the front wrap, otherwise bright and clean inside and out. Very good + condition.