共查询到20条相似文献,搜索用时 156 毫秒
1.
利用相干态正交化(ECS)法,讨论了两量子比特Rabi模型中的纠缠动力学问题,选取量子比特初态为交换对称的贝尔态,选取光场初态为真空态,分析了不同跃迁频率和不同光场-量子比特耦合强度下量子比特的纠缠演化特性。研究结果表明,在弱耦合情况下,当两个全同的量子比特的跃迁频率与光场频率的差值相同时,纠缠演化几乎相同;当非全同的量子比特跃迁频率相对光场频率对称失谐时,纠缠度比全同时大,失谐量越大,纠缠越强,且纠缠的变化周期与失谐量成反比。在共振情况下,当耦合强度不相等时,两量子比特纠缠演化存在主极大与次极大交替出现的现象;保持其中一个量子比特与光场的耦合强度不变,另一量子比特的耦合强度越强,次极大的峰值越大,但主峰峰值始终能达到最大纠缠;整个过程中纠缠演化表现出周期性。 相似文献
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非旋波近似下Λ型三能级原子与相干态光场的量子纠缠 总被引:1,自引:1,他引:0
在非旋波近似下,利用相干态正交化展开方法,对相干态光场与Λ型三能级原子相互作用的量子场熵进行了精确求解.利用量子熵理论讨论了耦合强度、平均光子数以及初始时刻原子处于不同的能级对量子纠缠的影响.数值计算的结果表明:当初始时刻原子处于激发态时,量子纠缠在较短的时间内就能演化到最大值,随着平均光子数的增大,纠缠演化的周期性逐渐明显;原子初始时刻处于三个能级的叠加态会使初始阶段量子纠缠显著降低;与旋波近似下的结果不同的是,随着耦合强度以及平均光子数的增加,非旋波项的贡献显著增强,使得量子纠缠演化曲线出现小锯齿状的振荡. 相似文献
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在非旋波近似下,利用相干态正交化展开方法,对相干态光场与Λ型三能级原子相互作用的量子场熵进行了精确求解.利用量子熵理论讨论了耦合强度、平均光子数以及初始时刻原子处于不同的能级对量子纠缠的影响.数值计算的结果表明:当初始时刻原子处于激发态时,量子纠缠在较短的时间内就能演化到最大值,随着平均光子数的增大,纠缠演化的周期性逐渐明显|原子初始时刻处于三个能级的叠加态会使初始阶段量子纠缠显著降低|与旋波近似下的结果不同的是,随着耦合强度以及平均光子数的增加,非旋波项的贡献显著增强,使得量子纠缠演化曲线出现小锯齿状的振荡. 相似文献
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M. Ban 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,58(3):415-421
Decoherence of interacting two qubits placed
under the influence of a common environment
is studied by means of the quantum master equation,
where the two qubits interact with each other
via the XY-coupling and the two-qubit system
has the dephasing coupling with the environment.
It is shown that when the asymmetry of the
interaction between the two-qubit system and environment
is not small,
the qubit-qubit interaction significantly affects
the dephasing of the two-qubit system.
To examine such an interaction effect,
the decay of two-qubit entanglement is calculated.
It is found that the qubit-qubit interaction makes not only
the decay of entanglement small
but also the period of the oscillatory behaviour short. 相似文献
12.
Entropy evolution properties in a system of two entangled atoms interacting with light field
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In this paper, we use the field entropy as a measurement of the degree of entanglement between the light field and the atoms of the system which is composed of two dipole—dipole interacting two-level atoms initially in an entangled state interacting with the single mode coherent field in a Kerr medium. The influence of the coupling constant of dipole—dipole interaction between atoms and the coupling strength of the Kerr medium with the light field and the intensity of the light field on the field entropy are discussed by numerical calculations. It is shown that when the coupling strength of the Kerr medium with the light field is large enough, and the light field is strong, the degree of entanglement between the atoms with the light field becomes weaker. The degree of entanglement only changes slightly with the change of the coupling constant of dipole—dipole interaction between atoms. 相似文献
13.
Entanglement dynamics of two qubits from environmental perturbations with different initial conditions is investigated. The results show that the qubit-qubit interaction leads to a periodic disentanglement and entanglement. It is surprised that the sudden death of entanglement (ESD) does not happen for non-interacting qubits, but for both the cases of a pure dephasing environment and a normal environment, ESD emerges. The results may provide a useful clue to implement an entanglement quantum information. 相似文献
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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.
耦合双Tavis-Cummings模型中的纠缠演化和转移特性 总被引:1,自引:0,他引:1
研究了由光纤模连接的两个Tavis-Cummings模型中纠缠演化和纠缠转移的特性。结果表明,初始两原子间的纠缠可转移为另两原子间的纠缠,在纠缠转移过程中,光纤模起到中间传递的作用。纠缠的转移与初始两原子间的纠缠、原子与腔场的耦合强度以及光纤模与腔场的耦合强度、原子与腔场的失谐量和腔场耗散有关。初始纠缠决定了另两原子间纠缠产生的大小;在原子与腔场的耦合强度一定的条件下,随着光纤模与腔场耦合强度的增强,纠缠转移的时间缩短,且产生的纠缠值增加;腔场耗散对纠缠演化的衰减影响是显著的,而失谐量的增加可以有效地抑制这一现象。在整个纠缠转移过程中,系统中其他任两子体系间的纠缠起到了桥梁的作用,实现了两量子纠缠态的远程传递和制备。 相似文献
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We introduce a new type of superconducting charge qubit that has a V-shaped energy spectrum and uses quantum interference to provide independently tunable qubit energy and coherent coupling to a superconducting cavity. Dynamic access to the strong coupling regime is demonstrated by tuning the coupling strength from less than 200 kHz to greater than 40 MHz. This tunable coupling can be used to protect the qubit from cavity-induced relaxation and avoid unwanted qubit-qubit interactions in a multiqubit system. 相似文献
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The concurrence evolution of two qubits coupled with one-mode cavity separately is investigated exactly without adopting the rotating-wave approximation. The results show that for the resonant case, the concurrence evolution behaviour of the system is similar to that of the Markovian case when the coupling strength is weak, while the concurrence vanishes in a finite time and might revive fractional initial entanglement before it permanently vanishes when the coupling strength is strong. And for the detuning case, the entanglement could periodically recover after complete disentanglement. These results are quite different from those of system subjected to Jaynes--Cummings model. 相似文献
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We have investigated the evolution of the atomic quantum entropy and the entanglement of atom-photon in the system with competing k-photon and l-photon transitions by means of fully quantum theory, and examined the effects of competing photon numbers (k and l), the relative coupling strength between the atom and the two-mode field (A/g), and the initial photon number of the field on the atomic quantum entropy and the entanglement of atom-photon. The results show that the multiphoton competing transitions or the large relative coupling strength can lead to the strong entanglement between atoms and photons. The maximal atom-photon entanglement can be prepared via the appropriate selection of system parameters and interaction time. 相似文献
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黄利元 《原子与分子物理学报》2021,38(6):065002
研究了两量子比特的海森堡XXX自旋链分别处于x方向和y方向均匀外磁场时系统的纠缠特性,并用负度N来度量。得到纠缠度N的解析表达式,并在此基础上进行数值计算。仔细讨论了磁场B、温度T和自旋耦合系数J对纠缠度N的影响。结果表明:纠缠度N会随着磁场|B|和温度T的增大而减小,但会随着自旋耦合系数J的增大而增大。另外,增大的J还会使临界磁场|Bc|和临界温度Tth变大。所以,我们可以通过调节B、T和J来控制热纠缠,这对固态系统中通过构建和选择参数调整系统的纠缠度具有一定的作用和意义。研究还发现,加在x方向均匀外磁场和加在y方向均匀外磁场对两量子比特的海森堡XXX自旋链的作用效果是一样的。 相似文献