The NMR system is one of the physical systems that can be used to realize quantum computation. However, NMR-based quantum computing could have many drawbacks with increasing qubit number. One of the underlying reasons is that the signal of pseudo-pure state decreases exponentially with increasing qubit number. Besides, the process required to prepare a pseudo-pure state becomes more complicated as the spin system gets larger. Furthermore, the pseudo-pure state in NMR system is in fact a mixed state, making it difficult to realize quantum entanglement. In this paper, we used parahydrogen induced polarization (PHIP) technique to prepare a genuine pure state for NMR quantum computation with significantly enhanced signal intensity. The initial state was applied to implement a two-qubit Deutsch-Jozsa algorithm and a three-qubit Deutsch-like algorithm.%核磁共振系统是实现量子计算的有效物理体系之一。但是随着量子位数的不断增加，运用核磁共振技术实现计算任务存在明显的局限性，原因之一是量子计算的初始态—赝纯态，随着量子位数的增加，信号指数性的衰减，量子位数越多制备赝纯态所需的脉冲序列越复杂，越不容易实现，不利于量子位数的扩展；另外，由于核磁共振中制备的赝纯态实际上也是一种混合态，用于实现量子信息任务时存在一定的争议。该文介绍的利用仲氢诱导极化技术(PHIP)制备出的实验初态，能够解决初态处于混合态的问题，并且信号强度显著增强，作者利用此态实现了ALTADENA条件下的两量子位的Deutsch-Jozsa量子算法和PASADENA条件下的三量子位的Deutsch-Like量子算法。
展开▼
