共查询到20条相似文献,搜索用时 140 毫秒
1.
2.
基于Braunstein和Kimble提出的B-K方案以双模最小关联混合态作为量子信道实施对未知量子态的隐形传送,并以传送相干态为例进行了研究.结果表明:双模最小关联混合态作为一种广义的Einstein-Podolsky-Rosen型纠缠态在实现量子隐形传态中能很好地担当量子信道的角色,在纠缠度和压缩度选择适当的条件下被传送未知量子态的保真度可以达到1.这是比双模压缩真空态更优越的量子信道.
关键词:
量子隐形传态
双模最小关联混合态
保真度 相似文献
3.
提出利用单个三粒子最大Greenberger-Horne-Zeilinger (GHZ)态或两个Einstein-Podolsky-Rosen (EPR)态作为量子信道确定性隐形传送任意三粒子GHZ态的两个方案,并将方案推广至隐形传送任意n(n≥4)粒子GHZ态的情况.讨论了量子信道受噪声影响时隐形传态的保真度.研究发现,当作为量子信道的单个三粒子最大GHZ态受到噪声影响时,隐形传态的保真度仅与量子信道的纠缠度有关,而当作为量子信道的两个EPR态受到噪声影响时,隐形传态的保真度不仅与量子信道的纠缠度有关,还与待传送态的纠缠度有关.所提出的方案具有节省量子信道纠缠资源的特点.
关键词:
隐形传态
三粒子Greenberger-Horne-Zeilinger态
量子逻辑门
保真度 相似文献
4.
5.
借助于双模压缩真空态在EPR纠缠态表象中的表示,研究了用双模压缩真空态作为量子通道 实现任意的单模和双模量子态的远程传输.
关键词:
量子隐形传态
EPR纠缠态
压缩真空态 相似文献
6.
7.
8.
9.
10.
11.
Quantum teleportation of one- and two-photon superposition states based on EPR entanglement of continuous-wave two-mode squeezed state is discussed. The fidelities of teleportation axe deduced for two different input quantum states. The dependence of the fidelity on the parameters of EPR entanglement and the gain of the classical channels are shown numerically. Comparing with the teleportation of Fock state and coherent state, it is pointed out that for given EPR entanglement and classical gain, the higher the nonclassicality of the input state, the lower the accessible fidelity of teleportation. 相似文献
12.
Effect of excess noise on continuous variable entanglement sudden death and Gaussian quantum discord 下载免费PDF全文
A symmetric two-mode Gaussian entangled state is used to investigate the effect of excess noise on entanglement sudden death and Gaussian quantum discord with continuous variables. The results show that the excess noise in the channel can lead to entanglement sudden death of a symmetric two-mode Gaussian entangled state, while Gaussian quantum discord never vanishes. As a practical application, the security of a quantum key distribution (QKD) scheme based on a symmetric two-mode Gaussian entangled state against collective Gaussian attacks is analyzed. The calculation results show that the secret key cannot be distilled when entanglement vanishes and only quantum discord exists in such a QKD scheme. 相似文献
13.
We present a realistic scheme for the entanglement swapping of continuous
variable, in which a two-mode squeezed vacuum state serves as a quantum
channel. The position sum and momentum difference of two local modes are
measured. By taking the input entangled state also as a two-mode squeezed
vacuum state, we investigate the average fidelity and the von Neumann
entropy of the output state. The results show that the
perfect teleportation can be
achieved by increasing the squeezing of the quantum channel and that any
nonzero squeezing in both the quantum channel and the input entangled state
is sufficient to swap the entanglement. 相似文献
14.
非绝热消除条件下输出边频量子关联 总被引:1,自引:0,他引:1
考虑了双模腔内含有N个三能级V型原子的系综与两个量子化场之间的相互作用。在非绝热消除原子变量的条件下,分析了两个初始为相干态的输入场从腔内输出后的量子关联性质。结果表明在恰当的条件下,在中心频率处可以获得量子纠缠,但随合作参数的增加,中心频率处的纠缠变小甚至消失。与此同时,在高频区间则产生了一对边频量子纠缠。这是由于合作参数增加引起的真空拉比分裂导致了高频处获得量子关联。此外,通过调节量子化场的强度以及原子和场的反对称失谐,还可获得两对边频量子纠缠。这对边频量子关联的研究具有十分重要的价值。 相似文献
15.
Properties on the distant distribution of entanglement for arbitrary two-qubit pure states via noisy quantum channels 下载免费PDF全文
This paper investigates the change of entanglement for transmitting
an arbitrarily entangled two-qubit pure state via one of three
typical kinds of noisy quantum channels: amplitude damping
quantum channel, phase damping quantum channel and depolarizing
quantum channel. It finds, in all these three cases, that the output
distant entanglement (measured by concurrence) reduces
proportionately with respect to its initial amount, and the decaying
ratio is determined only by the noisy characteristics of quantum
channels and independent of the form of initial input state. 相似文献
16.
连续变量六组份和八组份星型Cluster纠缠态光场产生系统 总被引:2,自引:2,他引:0
Cluster纠缠态是执行单向量子计算的基本资源。星型Cluster态可用于构建量子信息网络。以非简并光学参变放大器产生的双模压缩态光场为基础,设计了产生连续变量六组份和八组份星型Cluster纠缠态光场的实验方案,并推导了相应的量子不可分判据。计算结果指出,当量子不可分判据中的增益因子取为1时,需要一定的初始压缩度才能制备星型Cluster纠缠态;但当选取最佳增益因子时,极低的压缩也能产生星型纠缠。计算为实验系统设计提供了直接参考。 相似文献
17.
双模纠缠态是量子信息领域一种重要的量子资源,本文基于四波混频过程从理论上提出了对双模纠缠态的单个模式(单模放大方案)和对双模纠缠态的两个模式(双模放大方案)的放大.利用光学分束器模型来模拟在光学传输过程中损耗引入的真空场噪声,利用部分转置正定判据分析了两种不同的放大方案中四波混频过程的增益对初始双模纠缠态的纠缠程度的影响.结果表明,在特定的损耗情况下,两个方案中初始双模纠缠态的纠缠度都随增益的增大而减小,直至消失,且双模放大方案中初始双模纠缠态纠缠消失得比单模放大方案中更快.本文的理论结果为实验上实现基于四波混频过程的双模纠缠态的放大奠定了理论基础. 相似文献
18.
Optical enhanced interferometry with two-mode squeezed twin-Fock states and parity detection 下载免费PDF全文
We theoretically investigate the quantum enhanced metrology using two-mode squeezed twin-Fock states and parity detection. Our results indicate that, for a given initial squeezing parameter, compared with the two-mode squeezed vacuum state, both phase sensitivity and resolution can be enhanced when the two-mode squeezed twin-Fock state is considered as an input state of a Mach–Zehnder interferometer. Within a constraint on the total photon number, although the two-mode squeezed vacuum state gives the better phase sensitivity when the phase shift φ to be estimated approaches to zero, the phase sensitivity offered by these non-Gaussian entangled Gaussian states is relatively stable with respect to the phase shift itself. When the phase shift slightly deviates from φ= 0, the phase sensitivity can be still enhanced by the two-mode squeezed twin-Fock state over a broad range of the total mean photon number where the phase uncertainty is still below the quantum standard noise limit. Finally, we numerically prove that the quantum Cramer–Rao bound can be approached with the parity detection. 相似文献
19.
This paper introduces two types of two-mode excited entangled
coherent states (TMEECSs) |Ψ±(α,m,n)>, studies
their entanglement characteristics, and investigates the influence
of photon excitations on quantum entanglement. It shows that for the
state |Ψ+(α,m,m)> the two-mode photon excitations
affect seriously entanglement character while the state
|Ψ-(α,m,m)> is always a maximally entangled state,
and shows how such states can be produced by using cavity quantum
electrodynamics and quantum measurements. It finds that the
entanglement amount of the TMEECSs is larger than that of the
single-mode excited entangled coherent states with the same photon
excitation number. 相似文献
20.
研究了量子态在一条均匀耦合的反铁磁自旋链中传输时, 信道中自旋激发数变化对其传输性质的影响. 利用信息流方法分析输出端粒子的算符演化动力学, 获得了量子态传输的平均保真度与信道自旋初态之间的关系. 结果表明, 平均保真度的大小只依赖于信道中自旋激发数的奇偶性. 通过比较在奇偶激发信道中获得的最大平均保真度, 构建了优化信道来提升量子态在自旋链中的传输质量. 进一步分析了纠缠在激发信道中的传输情况, 发现纠缠的传输质量不仅和信道中自旋激发的具体个数有关, 还取决于激发自旋的初始排列. 特别地, 当信道中自旋无激发或全部激发时, 纠缠传输的大小和持续时间都优于其他的激发信道. 上述研究结果有助于在实际系统中搭建适合量子态和纠缠传输的量子信道. 相似文献