共查询到19条相似文献,搜索用时 156 毫秒
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利用一个参量频率转换过程,在腔中制备双模SU(2)相干态,然后注入A型三能级原子,使之与腔场的一个模发生Raman相互作用,生成腔场-原子纠缠态,通过对原子进行选择性测量,可获得奇偶SU(2)相干态.我们分别将原子能级和奇偶相干态编者按码为目标量子比特和控制量子比特,利用Raman相互作用可构造出类可控非门. 相似文献
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远程控制光场的量子统计性质 总被引:3,自引:0,他引:3
考虑双模纠缠相干光场,将其中一束光场注入腔中与一个二能级原子发生共振相互作用,总系统在腔量子电动力学演化过程中,对原子作选择性的测量,通过操纵参加相互作用的时间以及选择适当的光场参量可控制未参加相互作用光场的量子统计性质,在一定条件下可产生反聚束、压缩态等非经典光场,并且通过适当的控制和调整这些参量可以改变未参加相互作用光场的反聚束和压缩特性的强弱。这样,通过利用腔与原子之间简单的共振相互作用和相干光场之间的纠缠关联,实现了远程的、无直接量子测量的控制或改变相干光场的非经典性质这一目的。 相似文献
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远程制备双原子纠缠态 总被引:1,自引:1,他引:0
提出一种远程制备双原子纠缠态的方案,该方案基于两个原子与单模腔场的同时非共振相互作用.由于双粒子纠缠态比三粒子纠缠态容易制备,方案用两对双原子纠缠态作为量子通道.Alice 拥有的两个相同原子同时与一单模腔场非共振相互作用.Alice已知她要制备的纠缠态,她选择适当的相互作用时间、测量她所拥有的两个原子并通过经典通道通知Bob.Bob引入一个相同的辅助原子和一个单模腔场来实现方案.方案对腔场状态和腔损耗不敏感,基于当前的腔QED 技术,方案能在实验上实现.该方案有望在量子信息过程中有重要的应用价值. 相似文献
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碱金属原子跃迁线波段压缩态光场是量子信息以及精密测量领域的重要量子资源.碱金属原子跃迁线波长短(760—860 nm),受限于非线性晶体的灰迹效应,光参量放大器制备的此波段压缩态光场的压缩度有限,目前典型值约3—5 dB.本文在光参量放大器的理论模型基础上,结合原子跃迁线波段压缩态光场实验制备面临的问题,研究光参量放大器输出光场量子噪声随其物理参数的变化规律,获得最优的物理参数.构建了级联光参量放大器的理论模型,以此为基础分别在分析频率2 MHz和100 kHz,研究了级联环路光学损耗以及相位噪声对级联系统输出量子噪声特性的影响.研究发现,对于兆赫兹波段的压缩,在低的光路损耗以及位相噪声前提下,级联2—3个光参量放大器可实现压缩的显著提升;对于低频段压缩,级联系统对压缩的增强较小.在目前的实验参数条件下,进一步探究了级联系统输出压缩态光场的量子极限以及频谱特性.本研究可为原子跃迁线波段压缩态光场压缩度的提升提供参考和指导. 相似文献
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描述了简并Ⅴ型三能级原子与单模相干态光场的Raman相互作用,获得了处于激发态单态的原子与相干态光场相互作用的结果.利用探测原子与光场的相互作用将原子和探测光场制备成最大纠缠态,并将原子注入待测任一奇偶相干叠加态,通过原子与待测腔模构成的Bell基矢演化,对原子进行选择性探测,获得奇偶相干叠加态与原子相互作用后可能的量子状态,然后对待测腔场与原子进行联合探测,接着对所测奇偶相干态腔场的量子状态实施么正变换,就将探测腔场制备到待测腔场的初始量子态上,从而实现未知奇偶相干态的隐形传送. 相似文献
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描述了简并V型三能级原子与单模相干态光场的Raman相互作用,获得了处于激发态单态的原子与相干态光场相互作用的结果.利用探测原子与光场的相互作用将原子和光场制备成最大缠结态,并注入待测原子,通过原子与腔模构成的Bell基矢演化,对腔场进行选择性探测,获得探测原子相互作用后可能的量子状态,然后对待测原子与腔场进行联合探测,接着对探测原子的量子状态实施幺正变换,就将探测原子制备到待测原子的初始量子态上,从而实现未知原子态的隐形传送. 相似文献
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Connecting individual quantum systems through quantum channels leads to develop quantum networks crucial to perform multipartite communication or quantum cryptography. We present two techniques to generate entanglement among different parties at larger scale. In the first approach cavity QED technique is used to produce extended entanglement in atomic internal and external degrees of freedom. In this scheme we entangle two tagged atoms in their momentum state with cavity fields. Later, interaction of two auxiliary atoms with the two cavity fields in non-dispersive and dispersive fashion transforms the atoms–fields entanglement to atoms–atoms entanglement. Quantum measurement on auxiliary atoms generates extended entangled state in atomic degrees of freedom. In the second approach we take three cavities in which the two cavities have separate entangled state with third cavity in two modes which are distinguishable. Applying quantum measurement process on third cavity, we develop extended entangled state among the three cavities. We provide experimental parameters to realize the work in laboratory experiment. 相似文献
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Using a system of cavity quantum electrodynamics(QED) we present two schemes for multipartite entanglement generation. In the first scheme, a three-level atom is interacting with three cavities successively. In the second one, two three-level atoms are interacted with a coherent optical cavity. These protocols allow us to generate the six classes of tripartite entanglement(GHZ, W, A-B-C, AB-C, C-AB, and B-AC class states) by controling the interaction time between atoms and cavities. Moreover, they allow us to generate entanglement between the cavity fields degrees of freedom(from the first scheme), and a mixed entanglement between the cavity field degrees of freedom and the atomic degrees of freedom. 相似文献
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Quantum networks are distributed many-body quantum systems with tailored topology and controlled information exchange. We present two schemes to generate remote entanglement, in atomic external degrees of freedom and between cavities. In the first scheme, we entangle two atoms with their cavities in momentum space through Bragg diffraction. Thereafter, in order to trace out the cavities, we let resonantly interact an auxiliary atom with each cavity. In the last, we perform quantum measurement on two auxiliary atoms and get remote entangled state in atomic external degrees of freedom. In the second scheme, we have a three cavities system. The other two cavities, A and B, are entangled with indistinguishable modes of cavity, C. Performing quantum measurement on third cavity, C, we disentangle it from the system and the cavities, A and B, become entangled. 相似文献
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本文提出一个通过原子和腔场相互作用传送未知原子纠缠态的新方案,并且成功概率为100%.在这个方案里,我们主要利用两个原子用来接受被传送的原子纠缠态以及一个双模腔作为量子通道.由于腔场的两个模具有不同的频率和正交极化,因此这两个模能够被区分,并且处于腔场的不同区域.原子和腔场通过J-C哈密顿量发生共振相互作用,当原子和其中一个模相互作用时,另外一个模不受影响.该方案既不需要贝尔态测量,也不需要任何操作重构纠缠初态.这个方案也可以推广到传送N个原子的纠缠态. 相似文献
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Possible Realization of Cluster States and Quantum Information Transfer in Cavity QED via Raman Transition 下载免费PDF全文
We present a scheme to generate cluster states with many scheme, no transfer of quantum information between the atoms in cavity QED via Raman transition. In this atoms and cavities is required, the cavity fields are only virtually excited and thus the cavity decay is suppressed during the generation of cluster states. The atoms are always populated in the two ground states. Therefore, the scheme is insensitive to the atomic spontaneous emission and cavity decay. We also show how to transfer quantum information from one atom to another. 相似文献
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We propose two schemes for the generation of cluster states in the context of cavity quantum electrodynamics (QED). In the first scheme, we prepare multi-cavity cluster states with information encoded in the coherent states. The second scheme is to generate multi-atom cluster states, where qubits axe represented by the states of cascade Rydberg atoms. Both the schemes axe based on the atom-cavity interaction and the atomic spontaneous radiation can be efficiently reduced since the cavity frequency is largely detuned from the atomic transition frequency. 相似文献
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We investigate the generation and the evolution of continuous-variable (CV) entanglement from a laser-driven four-state atom inside a doubly resonant cavity under Raman excitation. Two transitions in the four-state atom independently interact with the two cavity modes, while two other transitions are driven by coupling laser fields. By including the atomic relaxation as well as cavity losses, we show that the CV entanglement with large mean number of
photons can be generated in our scheme. We also show that the intensity of the coupling laser fields can influence effectively the entanglement period of the cavity field. Different from the conventional resonant excitation scheme where zero one-photon detuning are required, it is found that the intensity and period of entanglement between the two cavity modes as well as the total mean photon number of the cavity field can be adjusted by properly
modulating the frequency detuning. 相似文献
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提出利用绝热过程实现远距离量子纠缠的方案.Λ型原子和经典场、单模腔场发生相互作用,系统的绝热演化在暗态中进行.利用这种绝热演化进行远距离原子、腔场纠缠,可有效地抑制原子的自发辐射噪声. 相似文献