STUDIES ON CLASSIFICATION OF QUANTUM CHANNEL INCLUDING QUANTUM TELEPORTATION AND FORMULATION OF QUANTUM LOGIC GATES

量子通道分类（包括量子隐形传态）和量子逻辑门的制定的研究

• 批准号: 14540138
• 负责人: WATANABE Noboru
• 金额: $ 2.11万
• 依托单位: TOKYO UNIVERSITY OF SCIENCE
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2005
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14540138/
• 关键词: QUANTUM TELEPORTATION; QUANTUM CHANNEL; QUANTUM LOGIC GATE; QUANTUM COMMUNICATION THEORY; QUANTUM INFORMATION THEORY; BEAM SPLITTER; SQUEEZED STATE; QUANTUM ENTANGLMENT; 量子力学的エントロピー; 量子相互エントロピー; Capacity

(1)Study of classification of a quantum channel including quantum teleportationUsual optical communication uses laser as a signal, which is represented by coherent state mathematically. By the way, it is remarked that quite effective communication will be realized by using the squeezed states obtained by squeezing the coherent states. In this study, (i)we construct the mathematical model of squeezing channel which transmits the squeezed states to the output states keeping squeezing property, that is, we construct a squeezing channel under the energy conservation using a squeezing unitary operator defined on symmetric Fock space ; (ii)based on the results of (1), we classified the quantum communication channels such as the coherent channel, the squeezing channel, the photon number channel and so on.(2)Study of construction of quantum logic gateThe irreversibility of the AND and OR gates gives an unavoided demerit in usual computer. One of the solutions of this demerit is a reversible logic gate with three inputs and three outputs introduced by Fredkin and Foffoli, which is called a FT gate. Miburn proposed a physical model of FT gate constructed by a Mach- Zender interferometer and a Kerr device, which is called a FTM gate. We reformulated this FTM gate by using the quantum channel and studied the efficiency of this FTM by means of the quantum mutual entropy. This FTM gate needs the photon number state which might be difficult to realize physicaly for the control gate. In this study, we construct FTM gate using coherent control states instead of the photon number state and we also introduced the new quantum logic gate with four beam splitters.

（1）包括量子传送的量子信道的分类研究光通信使用激光作为信号，其在数学上用相干态表示。同时指出，利用压缩相干态得到的压缩态可以实现相当有效的通信。本研究中，（i）建立了将压缩态传输到保持压缩特性的输出态的压缩通道的数学模型，即利用定义在对称Fock空间上的压缩幺正算符，构造了能量守恒的压缩通道;（ii）在（1）的基础上，对量子通信信道进行了分类，如相干信道、压缩信道、光子数信道等。（2）量子逻辑门构造的研究与门和或门的不可逆性是一般计算机中不可避免的缺点。Fredkin和Foffoli提出了一种三输入三输出的可逆逻辑门，称为FT门。Miburn提出了一种由马赫-曾德尔干涉仪和克尔器件构成的FT门的物理模型，称为FTM门。我们利用量子信道对FTM门进行了改进，并利用量子互熵研究了这种FTM门的效率。该FTM门需要光子数态，这对于控制门来说可能难以物理实现。在本研究中，我们用相干控制态代替光子数态来构造FTM门，并介绍了一种新的具有四个分束器的量子逻辑门。

项目成果

On error probability of FTM gate changing control signals

FTM换门控制信号的错误概率研究

• 发表时间: 2003
• 期刊: Research Reports of Meetings of Information Theory IT
• 作者: S.Oomori;N.Watanabe
• 通讯作者: N.Watanabe

N.Watanabe: "On KOW dynamical entropy for optical noisy channel"物性研究. (掲載予定).

N. Watanabe：“关于光学噪声通道的 KOW 动态熵”物理特性研究（待出版）。

H.Fujisaki, T.Miyadera, A.Tanaka: "Dynamical aspects of quantum entanglement for weakly coupled kicked tops"Physical Review E. 67. 66201 (2003)

H.Fujisaki、T.Miyadera、A.Tanaka：“弱耦合踢顶量子纠缠的动态方面”物理评论 E. 67. 66201 (2003)

On general Quantum mutual entropy and capacity

关于一般量子互熵和容量

• 发表时间: 2005
• 期刊: Foundations of Probability and Physics - 3, American Institute of Physics 750
• 作者: K.Mitani;S.Oshiro;K.-S.Saito;N.Watanabe
• 通讯作者: N.Watanabe

A.Shimizu, T.Miyadera, A.Ukena: "Anomalous quantum states in finite macroscopic systems"International Journal of Quantum Information. 1=4. 561-568 (2003)

A.Shimizu、T.Miyadera、A.Ukena：“有限宏观系统中的异常量子态”国际量子信息杂志。