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arXiv 1201.0891cs.LOquant-ph
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非确定性量子程序的终止

Termination of Nondeterministic Quantum Programs

Yangjia Li, Nengkun Yu, Mingsheng Ying

摘要:

我们定义了一个语言无关的模型,其中一个量子程序由一组有限的量子过程。这些过程由公共状态空间上的量子马尔可夫链表示。非确定性量子程序的执行由单个进程的一系列动作来建模。这些行为被描述为状态希尔伯特空间上的超算子。在执行的每一步中,都会不确定地选择一个进程来执行下一个操作。给出了非确定性量子程序的可达空间和发散态的一个刻画。建立了非确定性量子程序在可达空间中态的终止概率的0 - 1律。这些结果的结合导致一个必要和充分条件终止的非确定性量子程序。基于这个条件,我们找到了一个在有限维状态空间中检验非确定性量子程序终止性的算法。非确定性经典程序和量子程序之间的一个显著差异是通过例子显示的:有可能几个量子程序中的每一个都模拟了以概率1终止的同一个经典程序,但是由它们组成的非确定性程序由于在执行它们时所携带的干扰而以概率0终止。

英文摘要:

We define a language-independent model of nondeterministic quantum programs in which a quantum program consists of a finite set of quantum processes. These processes are represented by quantum Markov chains over the common state space. An execution of a nondeterministic quantum program is modeled by a sequence of actions of individual processes. These actions are described by super-operators on the state Hilbert space. At each step of an execution, a process is chosen nondeterministically to perform the next action. A characterization of reachable space and a characterization of diverging states of a nondeterministic quantum program are presented. We establish a zero-one law for termination probability of the states in the reachable space of a nondeterministic quantum program. A combination of these results leads to a necessary and sufficient condition for termination of nondeterministic quantum programs. Based on this condition, an algorithm is found for checking termination of nondeterministic quantum programs within a fixed finite-dimensional state space. A striking difference between nondeterministic classical and quantum programs is shown by example: it is possible that each of several quantum programs simulates the same classical program which terminates with probability 1, but the nondeterministic program consisting of them terminates with probability 0 due to the interference carried in the execution of them.

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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