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arXiv quant-ph/0206102quant-ph
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在NMR量子计算机上用多项式时间求解量子搜索问题

Solving the quantum search problem in polynomial time on an NMR quantum computer

Xijia Miao

摘要:

量子搜索问题是一个重要的问题,因为一般的NP问题可以有效地解决一个unsorted量子搜索算法。这里已经表明,量子搜索问题可以在NMR量子计算机上在多项式时间内解决。NMR系综量子计算是基于量子力学幺正动力学,即封闭量子系统和它的系综都服从同一个量子力学幺正动力学,而不是基于经典NMR量子计算的伪纯态或有效纯态。基于这一新原理,我们发展了常规的NMR多量子谱,从实验上解决了搜索问题。首先将搜索问题的解信息加载到由预言机幺正操作和预言机无关幺正操作构造的幺正演化传播子上,用于激发自旋系综中的多重量子相干性.然后利用多量子光谱技术从实验上提取溶液信息.讨论了如何增强量子搜索核磁共振多量子脉冲序列的输出信号,并提出了一些增强核磁共振信号的方法。本文的工作将有助于常规高场核磁共振机有效地解决量子搜索问题。

英文摘要:

The quantum search problem is an important problem due to the fact that a general NP problem can be solved efficiently by an unsorted quantum search algorithm. Here it has been shown that the quantum search problem could be solved in polynomial time on an NMR quantum computer. The NMR ensemble quantum computation is based on the quantum mechanical unitary dynamics that both a closed quantum system and its ensemble obey the same quantum mechanical unitary dynamics instead of on the pseudopure state or the effective pure state of the classical NMR quantum computation. Based on the new principle the conventional NMR multiple-quantum spectroscopy has been developed to solve experimentally the search problem. The solution information of the search problem is first loaded on the unitary evolution propagator which is constructed with the oracle unitary operation and oracle-independent unitary operations and is used to excite the multiple-quantum coherence in a spin ensemble. Then the multiple- quantum spectroscopy is used to extract experimentally the solution information. It has been discussed how to enhance the output NMR signal of the quantum search NMR multiple-quantum pulse sequence and some approaches to enhancing the NMR signal are also proposed. The present work could be helpful for conventional high field NMR machines to solve efficiently the quantum search problem.

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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