CAJ | 학술논문

量子特性在信息领域中有着独特的功能,在提高运算速度、确保信息安全、增大信息容量和提高检测精度等方面可能突破现有经典信息系统的极限.我们以液态NMR技术实现量子信息处理中的应用主题开展研究,所取得的成果包括:(1)利用NMR实验实现了2个无直接耦合自旋之间的量子密集编码和3个量子位之间的量子密集编码过程.实验结果表明:量子密集编码只需传送N-1个量子位便可以传递N个经典位的信息.(2)利用NMR实验实现了3种多量子算法;提出了一种实现n阶耦合变换的理论方法,根据这种方法可实现任意量子位的Deutsch-Jozsa算法.(3)提出了一种基于量子克隆的量子编码和纠错方案.该方案一方面说明了量子克隆与量子纠错存在一定程度上的联系;另一方面也反映出一些量子克隆过程本身具有一定的抗消相干的能力.(4)提出用2维NMR中的多量子相干实现无消相干子空间(DFS),并在实验上验证了该DFS的避错能力.本方法有效地利用了甲基中3个磁等价的氢核,把原本需要4个化学位移各不相同的核自旋构造的二逻辑位的DFS变成了只需2个化学位移各不相同的核自旋体系构造的二逻辑位的DFS,虽然用的核自旋数"更少",却能避免更多的错误算符.用多量子相干作为量子计算中的量子位,是一种全新的概念,可以充分利用磁等价的原子核自旋来构造多个量子位,从而扩展了可利用的量子位的数目.
양자특성재신식영역중유착독특적공능,재제고운산속도、학보신식안전、증대신식용량화제고검측정도등방면가능돌파현유경전신식계통적겁한.아문이액태NMR기술실현양자신식처리중적응용주제개전연구,소취득적성과포괄:(1)이용NMR실험실현료2개무직접우합자선지간적양자밀집편마화3개양자위지간적양자밀집편마과정.실험결과표명:양자밀집편마지수전송N-1개양자위편가이전체N개경전위적신식.(2)이용NMR실험실현료3충다양자산법;제출료일충실현n계우합변환적이론방법,근거저충방법가실현임의양자위적Deutsch-Jozsa산법.(3)제출료일충기우양자극륭적양자편마화규착방안.해방안일방면설명료양자극륭여양자규착존재일정정도상적련계;령일방면야반영출일사양자극륭과정본신구유일정적항소상간적능력.(4)제출용2유NMR중적다양자상간실현무소상간자공간(DFS),병재실험상험증료해DFS적피착능력.본방법유효지이용료갑기중3개자등개적경핵,파원본수요4개화학위이각불상동적핵자선구조적이라집위적DFS변성료지수2개화학위이각불상동적핵자선체계구조적이라집위적DFS,수연용적핵자선수"경소",각능피면경다적착오산부.용다양자상간작위양자계산중적양자위,시일충전신적개념,가이충분이용자등개적원자핵자선래구조다개양자위,종이확전료가이용적양자위적수목.
This paper presents our theoretical and nuclear magnetic resonance(NMR) experimental work on several QIPs including quantum super dense coding (QSDC), quantum algorithms, quantum error correction, and decoherence-free subspace. The main contents are, (1) Using NMR technique, we realize two kinds of QSDC. The experimental results show that QSDC only needs to transfer ( N - 1 )qubits during transmitting N bits classical information; (2) On NMR quantum computers, we realize three kinds of quantum algorithms that include four-qubit summing algorithm, four-qubit Deutsch-like algorithm and seven-qubit Deutsch-Jozsa algorithm; (3) We present a quantum error correction scheme based on quantum cloning. This scheme shows the relationship between quantum cloning and quantum error correction; (4) To avoid decoherence in quantum algorithms, we construct a decoherence-free subspace (DFS) by using multiple quantum coherences. The validity of this DFS is also experimentally verified on our NMR quantum computers. The DFS makes the three unaddressed protons in a CH3 group distinguished in two-dimensional (2D) NMR. It can protect against more error operators. This idea may provide new insights into extending the number of qubits in the sense that it effectively utilizes the magnetically equivalent nuclei.