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1.
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
2.
Hybrid entangled state(HES) is a new type of entanglement, which combines the advantages of an entangled polarization state and an entangled coherent state. HES is widely discussed in the applications of quantum communication and computation. In this paper, we propose three entanglement concentration protocols(ECPs) for Bell-type HES, W-type HES, and cluster-type HES, respectively. After performing these ECPs, we can obtain the maximally entangled HES with some success probability. All the ECPs exploit the single coherent state to complete the concentration. These protocols are based on the linear optics, which are feasible in future experiments. 相似文献
3.
We present a scheme for locally concentrating a non-maximally entangled four-photon cluster state into a maximally-entangled four-photon cluster state. This scheme has a high success probability. The controlled-NOT (CNOT) gate is a crucial ingredient in this scheme, and we use a nearly deterministic CNOT gate, which is similar with that first introduced by Nemoto et al. (Phgs. Rev. Lett., 2004, 93: 250502). This CNOT gate has a simple structure and does not need the strong nonlinearity. 相似文献
4.
The entangled coherent states (ECSs) have been widely used to realize quantum information processing tasks. However, the ECSs may suffer from photon loss and decoherence due to the inherent noise in quantum channel, which may degrade the fidelity of ECSs. To overcome these obstacles, we present a measurement-based entanglement purification protocol (MBEPP) for ECSs to distill some highquality ECSs from a large number of low-quality copies. We first show the principle of this MBEPP without considering the photon loss. After that, we prove that this MBEPP is feasible to correct the error resulted from the photon loss. Additionally, this MBEPP only requires to operate the Bell state measurement without performing local two-qubit gates on the noisy pairs and the purified high-quality ECSs can be preserved for other applications. This MBEPP may have application potential in the implementation of long-distance quantum communication. 相似文献
5.
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
6.
We analyze entanglement properties of entangled coherent state (ECS), |α,0) 1,2 +|0,α) 1,2, with and without photon losses. By separating the coherent state into ]a) = co|0) + √-Co2|α), we derive exact results of the logarithmic negativity EN, which quantifies the degree of entanglement between the two bosonic modes. Without particle losses, E~ = 1 for the NOON state; while for the ECS, E jr increases from 0 to 1 as |α|-→∞. In the presence of photon losses, we find that the ECS with large enough photon number is more robust than that of the NOON state. An optimal ECS is obtained by maximizing E~ with respect to l a 12. 相似文献
7.
Optimal entanglement concentration for three-photon W states with parity check measurement 下载免费PDF全文
We present an efficient entanglement concentration protocol(ECP) for the less-entangled W state with some identical conventional polarized single photons.In the protocol,two of the parties say Alice and Charlie should perform the parity check measurements and they can ultimately obtain the maximally entangled W state with a certain success probability.Otherwise,they can obtain another less-entangled W state,which can be reconcentrated into the maximally entangled W state.By iterating this ECP,a high success probability can be achieved.This ECP may be an optimal one and it is useful in current quantum information processing. 相似文献
8.
Dynamics of a multi-mode maximum entangled coherent state over an amplitude damping channel 下载免费PDF全文
The dynamics of the maximum entangled coherent state traveling through an amplitude damping channel is investigated. For small values of the transmissivity rate, the traveling state is very fragile to this noise channel, which suffers from the phase flip error with high probability. The entanglement decays smoothly for larger values of the transmissivity rate and speedily for smaller values of this rate. As the number of modes increases, the traveling state over this noise channel quickly loses its entanglement. The odd and even states vanish at the same value of field intensity. 相似文献
9.
Although the multi-level structure of superconducting qubits may result in calculation errors, it can be rationally used to effectively improve the speed of gate operations. Utilizing a current-biased Josephson junction (A-type rf-SQUID) as a tunable coupler for superconducting transmission line resonators (TLRs), under the large detuning condition, we demonstrate the controllable generation of entangled coherent states in circuit quantum electrodynamics (circuit QED). The coupling between the TLRs and the qubit can be effectively regulated by an external bias current or coupling capacitor. Further investigations indicate that the maximum entangled state can be obtained through measuring the excited state of the superconducting qubits. Then, the influence of the TLR [tecay on the prepared entangled states is analyzed. 相似文献
10.
基于具有两个近似简并基态(|g〉,|e〉)和一个激发态(|r〉)的三能级原子的两基态为静态量子比特,光子数态为飞行量子比特.两对非最大原子纠缠对中各有一个原子被分别囚禁在两个泄露腔中,在大失谐极限和激发态自发辐射系数γ远小于失谐量Δ的情况下,利用经典激光脉冲激发和与量子化腔场耦合作用后,通过对从腔中泄露出来的光子进行探测,可以将两对未知非最大原子纠缠态以一定的概率浓缩成最大纠缠态.充分考虑并且利用了腔的衰减,增强了实验的可行性和进行远距离的纠缠态浓缩的实现. 相似文献
11.
This paper proposes a feasible scheme for the quantum teleportation
of tripartite entangled coherent states by using linear optical
devices such as beam splitters, phase shifters and photo detectors.
The scheme is based on the bipartite maximally entangled coherent
state and the tripartite entangled coherent state with bipartite
maximal entanglement as quantum channels. It shows that when the
mean number of photons is equal to 2, the total minimum of the average
fidelity for an arbitrary tripartite entangled state is 1-0.67×10 -3. 相似文献
12.
13.
介绍了量子干涉雷达物理模型及其探测原理,并采用耗散-涨落通道处理量子光场在湍流大气中的传输,从经典湍流统计理论推导得到大气透射率的概率密度分布函数P(T),以此为基础系统分析了大气闪烁效应对纠缠相干态量子干涉雷达的影响机理,深入讨论了平均大气透射率、闪烁指数等大气参数对系统目标探测性能的影响.研究发现:低损耗情况下系统灵敏度及分辨率性能随闪烁指数的增加而降低;高损耗情况下大气闪烁则能显著提高系统灵敏度和分辨率性能,且界定高低损耗的透射率临界点随脉冲光子数增加而增加,故大气闪烁能够在一定程度上克服大气损耗造成的不良影响. 相似文献
14.
研究由三个全同的二能级原子与耦合腔构成的系统, 考虑腔场处于弱相干态的情况. 采用Negativity熵度量两子系统间的纠缠, 利用数值计算方法研究了两个原子之间和两个腔场之间的纠缠性质. 讨论了腔场间的耦合系数和腔场的强度对纠缠特性的影响. 研究结果表明: 随光场强度增大, 原子间纠缠和腔场间纠缠均增强. 另一方面, 随耦合腔的耦合系数增大, 两原子间的纠缠减弱, 腔A和腔B间的纠缠增强; 而腔B和腔C间的纠缠, 以及腔A和腔C间纠缠与腔场间的耦合系数间存在非线性关系. 相似文献
15.
A novel quantum dual signature scheme, which combines two signed messages expected to be sent to two diverse receivers Bob and Charlie, is designed by applying entanglement swapping with coherent states. The signatory Alice signs two different messages with unitary operations(corresponding to the secret keys) and applies entanglement swapping to generate a quantum dual signature. The dual signature is firstly sent to the verifier Bob who extracts and verifies the signature of one message and transmits the rest of the dual signature to the verifier Charlie who verifies the signature of the other message. The transmission of the dual signature is realized with quantum teleportation of coherent states. The analysis shows that the security of secret keys and the security criteria of the signature protocol can be greatly guaranteed.An extensional multi-party quantum dual signature scheme which considers the case with more than three participants is also proposed in this paper and this scheme can remain secure. The proposed schemes are completely suited for the quantum communication network including multiple participants and can be applied to the e-commerce system which requires a secure payment among the customer, business and bank. 相似文献
16.
We present a scheme to prepare cluster-type entangled squeezed vacuum states (CTESVS) by considering the two-photon interaction between a two-level atom and a high-quality cavity, driven by a strong classical field. After the realization of simple atomic measurements, the generation of CTESVS in four separate cavities is accomplished within the cavity decay time. In the case of large atom=cavity detuning, the scheme is immune to the effect of atomic spontaneous emission. 相似文献
17.
Preparation of multicomponent motional coherent and squeezed coherent states of a trapped ion 总被引:1,自引:0,他引:1 下载免费PDF全文
In this paper, we present a scheme for preparation of multicomponent motional coherent and squeezed coherent states of the quantized centre of mass of an ion trapped in a one-dimensional harmonic potential and driven by two travelling-wave laser beams tuned to the nth red and blue vibrational sidebands, respectively. In addition, our scheme also provides experimental possibility for quantum state engineering. 相似文献
18.
用量子信息学的观点,分析了发生在一个多个原子和腔场组成的系统中最大纠缠态在原子和多模类奇-偶相干态光场之间相互转移的物理过程,该系统中原子和腔场之间由依赖于强 度耦合的Jaynes-Cummings模型描述.结果发现:通过控制原子与腔场相互作用的时间,并 对原子的状态进行测量,原子的最大纠缠态可以转换为类奇-偶相干态光场的最大纠缠态,反之,纠缠的多模类奇-偶相干态光场也可以转换为原子的最大纠缠态.
关键词:
量子信息
腔量子电动力学
连续变量纠缠态
纠缠交换和传递 相似文献
19.
Bell态原子与双模纠缠相干光场相互作用的纠缠特性 总被引:1,自引:0,他引:1
运用Negativity熵研究了Bell态原子与双模纠缠相干光场相互作用系统中两个全同二能级原子之间的纠缠演化特性.分析了光场强度、光场纠缠度及原子间相互作用强度对纠缠的影响.结果表明:原子处于|β11〉时,两原子始终处于最大纠缠态;原子处于|β00〉时,初始纠缠的两原子始终较长时间处于退纠缠状态;原子处在|β10〉时,增大双模光场的平均光子数可以明显增大两原子之间的纠缠度并保持较大的纠缠状态;原子初态处在|β01〉时,原子间的相互作用强度对双原子间纠缠度有较显著的非线性调制作用. 相似文献