基于量子隐形传态的量子保密通信方案

量子保密通信包括量子密钥分发、量子安全直接通信和量子秘密共享等主要形式.在量子密钥分发和秘密共享中,传输的是随机数而不是信息,要再经过一次经典通信才能完成信息的传输.在量子信道直接传输信息的量子通信形式是量子安全直接通信.基于量子隐形传态的量子通信(简称量子隐形传态通信)是否属于量子安全直接通信尚需解释.构造了一个量子隐形传态通信方案,给出了具体的操作步骤.与一般的量子隐形传态不同,量子隐形传态通信所传输的量子态是计算基矢态,大大简化了贝尔基测量和单粒子操作.分析结果表明,量子隐形传态通信等价于包含了全用型量子密钥分发和经典通信的复合过程,不是量子安全直接通信,其传输受到中间介质和距离的影响,所以不比量子密钥分发更有优势.将该方案与量子密钥分发、量子安全直接通信和经典一次性便笺密码方案进行对比,通过几个通信参数的比较给出各个方案的特点,还特别讨论了各方案在空间量子通信方面的特点.     

漫谈量子保密通信的中间人攻击问题

量子保密通信主要包括量子密钥分发①②和量子直接通信③④⑤.Bennett和Brassard在1984年提出的量子密钥分发,实际上是密码学中的密钥协商,Alice和Bob双方传输随机数,在确定其安全后,将传输的随机数升级为密钥,用于经典保密通信.密码学中的密钥分发是把事先确定好的密钥传送给指定的接收方.     

Effect of Transverse Correlation Function on the Thermodynamic Quantities of Ferromagnetic Systems

The effect of transverse correlation between spins on the thermodynamic properties of ferromagnetic systems is investigated in details. Qualitatively, at finite temperature the transverse correlation reflects the short-range interaction between spins, so that lowers the internal energy and consequently raises the free energy. It also means the introduction of some ordering, and hence lowers the entropy. It is depressed by the field which forces the spins to turn to the field direction, so that it decreases with the field when temperature is fixed. The low-temperature expansion of the energy shows that the inclusion of the transverse correlation at least partly considers the interaction between spin waves.     

量子直接通信研究进展

量子直接通信是一种在量子信道直接传输机密信息的量子保密通信技术,与经典通信实现在噪声信道下的可靠通信不同,它可实现在既有噪声又有窃听信道下的可靠和安全通信.通过阐述量子直接通信的原理、20年来的主要发展阶段、由理论走向实用化过程中突破的技术难点,分析并展望了量子直接通信的未来发展与应用前景.     

A Comparative Study of Quantum and Classical Deletion

Here in this letter, we study the difference between quantum and classical deletion. We point out that the linear mapping deletion operation used in the impossibility proof for quantum systems applies also to classical system. The general classical deletion operation is a combined operation of measurement and transformation, i.e., first read the state and then transfer the state to the standard blank state. Though both quantum information and classical information can be deleted in an open system, quantum information cannot be recovered while classical information can be recovered.     

一种电子-核子双自旋固体量子计算机实现方案

提出了一种利用电子-核子自旋的半导体固体量子计算机实现方案，通过扫描隧道显微镜的针尖实现单个比特的寻址、操作以及任意两个比特之间的受控非门操作，方案中所涉及到的技术是目前已有的或是接近于现有的技术水平，所提出的方案有可能利用现有的技术来实现。     

核磁共振量子计算机与并行量子计算(续)

2　核磁共振量子计算机2 .1　量子计算机物理实现的基本要求量子计算可以分三个步骤 ;第一是对体系进行初始化 ,将其制备成计算所需要的输入状态 ;第二是对量子体系进行操作 ,也就是对之进行幺正变换 ,让它按照实际要求进行演化 ,这就是量子计算的过程 ,是整个量子计算的核心 ;第三是正确读出运算结果 .因此 ,对做量子计算的物理体系的要求是 :(1 )有一个合适的 2能级体系来作为量子比特 ,这些量子比特可以被很好地表征 ;(2 )能够将体系进行初始化到一个所需要的量子态上 ,如| 0… 0〉 ;(3 )各量子位之间应存在合适的相互作用类型 ,而且可以…     

176Yb的β衰变

采用投影壳模型对¹⁷⁶Yb的β衰变进行了计算, 并与实验结果进行了比较.     

Triaxial interaction effect in the structure of ^148-158Sm

The structures of ^148-158Sm are studied in the frame of the interacting boson model. Attention is given to the triaxial interaction, and it is found that the triaxial interaction plays an important role in the detailed structure of this isotopic chain. The potential surfaces of these nuclei are also studied and the shapes of them are analysed. And it is found that though the triaxial interaction plays an important role in these nuclei, there are no stable triaxial shapes in the low-lying structures of these nuclei.     

原子核代数模型中的F-旋混合态、回弯、电磁跃迁问题的研究

在原子核的代数模型框架下,讨论了集体回弯效应、较高自旋的Ｆ－旋混合对称态以及电磁跃迁几率等问题． The collective backbending effect, F spin mixed symmetry states have been studied for the nuclei with moderate high spins. It is found that there is an additional L(L+3) proportional term in the E2 transition rates in the sdg interacting boson model and solved the long standing problem of reduction of collectivity in the wave function of boson models. The electromagnetic transitions in the spdf interacting boson model have been calculated and compared with existing experimental...