共查询到20条相似文献,搜索用时 15 毫秒
1.
We present an efficient faithful multipartite polarization entanglement distribution protocol over an arbitrary noisy channel. The spatial degree of freedom is used to carry the entanglement during the transmission. We describe the principle by distributing n-qubit Greenberge-Horne-Zeilinger state and n-qubit W state. Our scheme can be used to distribute arbitrary n-qubit entangled states to n distant locations. The remote parties can obtain maximally entangled states deterministically on the polarization of photons. Only passive linear optics are employed in our setup, which makes our scheme more feasible and efficient for practical application in long distance quantum communication. 相似文献
2.
Efficient Polarization Entanglement Distribution for W State Assisted by Frequency Degree of Freedom
We present an efficient faithful polarization entanglement distribution protocol for W state over an arbitrary noise channel,which use the frequency degree of freedom to carry the entanglement during the transmission.We describe the transmission of three-photon W state as an example,and then generalize this scheme to n-qubit W state situation.The remote parties can obtain maximally entangled W states on the polarization of photons,and the success probability is 100% in principle.As there was few entanglement purification for W state,our scheme is an efficient and practical method to share W state entanglement between distant parties,which will be useful in quantum communication.We also show that our scheme can be used to distribute arbitrary multi-particle entangled state. 相似文献
3.
A genuine multipartite entanglement measure based on the geometric method is investigated in this paper. This measure has desirable properties for quantifying the genuine multipartite entanglement. A lower bound of the genuine multipartite entanglement measure derived with the fidelity-based method is then presented. The advantages of the measure proposed here with other measures are also presented. At last, examples are presented to show that the genuine entanglement measure has distinct entanglement ordering from other measures. 相似文献
4.
CAO Ya WANG An-Min 《理论物理通讯》2009,51(4):613-620
Based on the revised geometric measure of entanglement (RGME) proposed by us [J. Phys. A: Math. Theor. 40 (2007) 3507], we obtain the RGME of multipartite state including three-qubit GHZ state, W state, and the generalized Smolin state (GSS) in the presence of noise and the two-mode squeezed thermal state. Moreover, we compare their RGME with geometric measure of entanglement (GME) and relative entropy of entanglement (RE). The results indicate RGME is an appropriate measure of entanglement. Finally, we define the Gaussian GME which is an entangled monotone. 相似文献
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We propose an efficient protocol for W polarization entangled state distribution over an arbitrary collective-noise channel with the help of the cross-Kerr nonlinearity. The entangled state in the frequency degree of freedom, which suffers little from the noise in an optical fiber, is used in the present protocol. The frequency entanglement can be transferred into polarization entanglement with the success probability of 100%. So, the three parities can share the maximally W polarization state with local operations and polarization independent wavelength division multiplexers which can erase distinguishability for frequency. 相似文献
7.
Entanglement diversion and quantum teleportation of entangled coherent states 总被引:2,自引:0,他引:2 下载免费PDF全文
The proposals on entanglement diversion and quantum teleportation of
entangled coherent states are presented.In these proposals, the entanglement between two coherent states, $|\alpha\rangle$ and $|-\alpha\rangle$, with the same amplitude but a phase difference
of $\pi$ is utilized as a quantum channel. The processes of the entanglement diversion and the teleportation are achieved by using the 50/50 symmetric beam splitters, the phase shifters and the photodetectors with the help of classical information. 相似文献
8.
The number of least degrees of freedom required for a polarization controller to transform any state of polarization to any other output covering the entire Poincaré sphere 下载免费PDF全文
Using two typical types of polarization controller, this paper
analyses theoretically and experimentally the fact that it is
necessary to adjust at least three instead of two waveplates in
order to transform any state of polarization to any other output
covering the entire Poincar\'{e} sphere. The experimental results
are exactly in accordance with the theory discussed in this paper.
It has corrected the conventional and inaccurate point of view that
two waveplates of a polarization controller are adequate to complete
the transformation of state of polarization. 相似文献
9.
YUAN Hong-Chun LI Heng-Mei QI Kai-Guo 《理论物理通讯》2005,44(6):1015-1020
By extending the EPR bipartite entanglement to multipartite case, we briefly introduce a continuous multipartite entangled representation and its canonical conjugate state in the multi-mode Fock space, analyze their Schmidt decompositions and give their entangling operators. Furthermore, based on the above analysis we also find the n-mode Wigner operator. In doing so we may identify the physical meaning of the marginal distribution of the Wigner function. 相似文献
10.
By extending the EPR bipartite entanglement to multipartite case, we briefly introduce a continuous multipartite entangled representation and its canonical conjugate state in the multi-mode Fock space, analyze their Schmidt decompositions and give their entangling operators. Furthermore, based on the above analysis we also find the n-mode Wigner operator. In doing so we may identify the physical meaning of the marginal distribution of the Wigner function. 相似文献
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Scheme for Teleportation of a Multipartite Quantum State by Using a Single Entangled Pair as Quantum Channel 总被引:2,自引:0,他引:2
We present a theoretical scheme for perfect teleportation of an unknown multipartite two-level state by a single EPR (Einstein-Podolsky-Rosen) pair,and then generalize it to multilevel,i.e.,an N-quNit state can be teleported by a single quNit entangled pair,with additional local unitary operations.The feature of the scheme is that teleporting a multipartite state with a reduced amount of entanglement costs less classical bits. 相似文献
13.
两纠缠原子与光场相互作用系统场熵演化特性 总被引:2,自引:0,他引:2
研究了两纠缠原子与相干态光场相互作用系统场熵的时间演化特性,运用全量子力学理论和数值方法,讨论了初始两原子所处的纠缠状态、纠缠度和腔内光场的强弱对场熵的影响.随着光场平均光子数的增加,系统场熵均值和振荡频率增大;光场较弱时,场熵呈现一定的周期性振荡;光场增强后,场熵呈现出周期性的崩塌与回复,且随初始两原子纠缠度的增加,场熵的振幅增大. 相似文献
14.
提出了一种制备三光子纠缠W态的方案, 该方案利用携带轨道角动量为lħ的光子(其中l可取(-∞, +∞)的任意整数)可构成无穷维向量空间的特性, 采用两种类型的参量下转换, 产生轨道角动量-自旋角动量纠缠的两对光子和一对偏振纠缠光子, 通过纠缠交换制备三光子多自由度的W态, 实现三光子体系纠缠的高维度、大容量量子信息处理. 方案采用q-plate相位光学器件和单模光纤等器件制备两个不同自由度(轨道角动量与偏振)混合的W态, 并利用计算机全息相位图改进方案制备三个不同自由度(轨道角动量、线动量和偏振)混合的W态. 本方案可稳定产生两种等概率互为对称的W态, 具有高维度、强纠缠特性与抗比特丢失能力, 信息量达log2m+2比特(m为l的可取值个数), 有望实现可扩容量子比特的安全通信. 相似文献
15.
Smail Bougouffa 《Optics Communications》2010,283(14):2989-2996
An experimental scheme is suggested that permits a direct measure of entanglement in a two-qubit cavity system. It is realized in the cavity-QED technology utilizing atoms as flying qubits. With this scheme we generate two different measures of entanglement, namely logarithmic negativity and concurrence. The phenomenon of sudden death entanglement (ESD) in a bipartite system subjected to dissipative environment is examined. We show that the sudden death time of the entangled states depends on the initial preparation of the entangled state and the temperature of the reservoir. 相似文献
16.
A deterministic quantum key distribution scheme using two non-orthogonal entangled states is proposed.In the proposed scheme,communicators share key information by exchanging one travelling photon with two random and secret polarization angles.The security of the distributed key is guaranteed by three checking phases in three-way channel and the communicators' secret polarization angles. 相似文献
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基于激光主动成像的烟雾环境下的目标探测具有重要研究意义,有效抑制光的散射作用是提高烟雾环境下成像质量的关键。根据光的偏振理论,仿真分析了光子单次散射的偏振特性与散射角的变化关系,并利用蒙特卡罗方法模拟了光在烟雾环境中传输的偏振特性,提出了利用偏振差法来抑制光散射作用,最后进行了简单的成像实验。结果表明,光在烟雾中传输时散射光主要由小角度散射光构成,仍然保留了初始激光的部分偏振特性,相比于直接灰度成像,偏振差法能够有效滤除小角度散射光的影响,增强成像目标的细节信息和图像的对比度。 相似文献
19.
A method of the calculation of spatial birefringence distribution in an optical fiber link is presented. This method is based
on analysis of the polarization properties of the backscattered optical signal. The analytical results are compared with numerical
results. This comparison gives excellent agreement. The spatial birefringence distribution is evaluated from the measurement
of the round-trip Mueller matrices derived from calculation of the angles between the input and output state of polarization. 相似文献
20.
Entanglement spectrum of finite-size correlated electron systems are investigated using the Gutzwiller projection technique. The product of largest eigenvalue and rank of the block reduced density matrix, which is a measure of distance of the state from the maximally entangled state of the corresponding rank, is seen to characterise the insulator to metal crossover in the state. The fraction of distinct eigenvalues exhibits a ‘chaotic’ behaviour in the crossover region, and it shows a ‘integrable’ behaviour at both insulating and metallic ends. The integrated entanglement spectrum obeys conformal field theory (CFT) prediction at the metal and insulator ends, but shows a noticeable deviation from CFT prediction in the crossover regime, thus it can also track a metal–insulator crossover. A modification of the CFT result for the entanglement spectrum for finite size is proposed which holds in the crossover regime also. The adjacent level spacing distribution of unfolded non-zero eigenvalues for intermediate values of Gutzwiller projection parameter g is the same as that of an ensemble of random matrices obtained by replacing each block of reduced density matrix by a random real symmetric Toeplitz matrix. It is strongly peaked at zero, with an exponential tail proportional to e−(n/R)s, where s is the adjacent level spacing, n is number of distinct eigenvalues and R is the rank of the reduced density matrix. 相似文献