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arXiv quant-ph/9605022quant-ph
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量子力学中的量子弹道演化:在量子计算机中的应用

Quantum Ballistic Evolution in Quantum Mechanics: Application to Quantum Computers

Paul Benioff

摘要:

量子计算机是过程的重要例子,其演化可以用单步算子或其伴随算子的迭代来描述。在此基础上,研究了含阶跃算子$T$过程的Hamilton演化.本文的主要限制是量子弹道演化的过程,即运动任意限制在一组不相交或不同的路径上。本文的主要目的是证明一个定理,该定理给出了T必须满足的充要条件,使得该过程存在量子弹道演化的哈密顿描述,即T是部分等距的,并且在一定的基上保持正交性和稳定性.讨论了具有一种和多种基本步骤的量子图灵机的量子弹道演化的简单例子。可以看出,对于非确定性机器,基组可以是相当复杂的,存在很多纠缠。证明了对于任意确定性量子图灵机,给定一个阶跃算子T,若T是稳定的且保持正交性,且量子弹道演化是可能的,则T是可判定的.证明失败,如果T是一个不确定机器的步骤操作符。这是一个悬而未决的问题,如果这样的决策过程存在的非确定性机器。这个问题在经典力学中不会出现。

英文摘要:

Quantum computers are important examples of processes whose evolution can be described in terms of iterations of single step operators or their adjoints. Based on this, Hamiltonian evolution of processes with associated step operators $T$ is investigated here. The main limitation of this paper is to processes which evolve quantum ballistically, i.e. motion restricted to a collection of nonintersecting or distinct paths on an arbitrary basis. The main goal of this paper is proof of a theorem which gives necessary and sufficient conditions that T must satisfy so that there exists a Hamiltonian description of quantum ballistic evolution for the process, namely, that T is a partial isometry and is orthogonality preserving and stable on some basis. Simple examples of quantum ballistic evolution for quantum Turing machines with one and with more than one type of elementary step are discussed. It is seen that for nondeterministic machines the basis set can be quite complex with much entanglement present. It is also proved that, given a step operator T for an arbitrary deterministic quantum Turing machine, it is decidable if T is stable and orthogonality preserving, and if quantum ballistic evolution is possible. The proof fails if T is a step operator for a nondeterministic machine. It is an open question if such a decision procedure exists for nondeterministic machines. This problem does not occur in classical mechanics.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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