共查询到20条相似文献,搜索用时 31 毫秒
1.
研究了受激拉曼绝热过程中原子-异核-三聚物分子转化系统暗态的动力学稳定性.通过将量子哈密顿对应到经典哈密顿,并求解和分析线性化经典运动方程后得到的哈密顿-雅克比矩阵本征值,解析地得到了原子-三聚物暗态的动力学不稳定性发生的条件.并以异核原子87Rb和41K混合凝聚体为例,数值地给出了系统发生动力学不稳定性的区域.研究发现,这种动力学不稳定性是由粒子之间的相互作用带来的.此外,还发现系统动力学不稳定性的发生不仅与哈密顿-雅克比矩阵是否出现实数或复数的本征值有关,还
关键词:
原子-异核-三聚物分子转化系统
暗态
受激拉曼绝热过程
动力学不稳定性 相似文献
2.
Instability,adiabaticity, and controlling effects of external fields for the dark state in a homonuclear atom tetramer conversion system 下载免费PDF全文
In the present paper, we investigate the instability, adiabaticity, and controlling effects of external fields for a dark state in a homonuclear atom-tetramer conversion that is implemented by a generalized stimulated Raman adiabatic passage. We analytically obtain the regions for the appearance of dynamical instability and study the adiabatic evolution by a newly defined adiabatic fidelity. Moreover, the effects of the external field parameters and the spontaneous emissions on the conversion efficiency are also investigated. 相似文献
3.
利用绝热演化,文章提出一种新的方法以实现量子相位门,这种相位移动既非源于动力学过程,也非源于几何操纵,它来源于暗态本身的演化,基于绝热演化的优点,这种量子逻辑门对实验参量的起伏不敏感,与几何相位门相比,这种相位门更简单,并且保真度可得到进一步提高。文章对这种相位门做一简述。 相似文献
4.
5.
从原子-二聚物分子转化系统的非U(1)对称性出发,将保真度的定义推广到了非线性系统.并利用绝热保真度定量地研究了原子-二聚物分子转化系统在受激拉曼绝热过程中的动力学和绝热性.研究发现,这个系统的相干布居俘获态——暗态的绝热保真度作为绝热参量的函数以幂律关系趋于1.这个函数关系与线性系统的绝热参量和绝热保真度的幂律关系非常相似,但该系统的幂指数要远小于线性系统的幂指数.此外,还进一步讨论了如何通过优化受激拉曼绝热过程的外部参量得到更高的绝热保真度,从而优化系统的绝热性,提高原子-分子转化效率.
关键词:
原子-二聚物分子转化系统
暗态
受激拉曼绝热过程
绝热保真度 相似文献
6.
Dynamical instability of the dark state in the conversion of Bose-Fermi mixtures into stable molecules 下载免费PDF全文
In this paper,we investigate the dynamical instability of the dark state in the conversion of Bose-Fermi mixtures into stable molecules through a stimulated Raman adiabatic passage aided by Feshbach resonance.We analytically obtain the regions where the dynamical instability appears and find that such instability in the Bose-Fermi mixture system is caused not only by bosonic interparticle interactions but also by Pauli blocking terms,which is different from the scenario of a pure bosonic system where instability is induced by nonlinear interparticle collisions.Taking a 40 K-87 Rb mixture as an example,we give the unstable regions numerically. 相似文献
7.
8.
Linear instability and adiabaticity of a dark state during conversion of two species of fermionic atoms to stable molecules 下载免费PDF全文
In the present paper, we investigate the linear instability and adiabaticity of a dark state during conversion of two species of fermionic atoms to stable molecules through the stimulated Raman adiabatic passage aided by Feshbach resonance. We analytically obtain the regions for the appearance of linear instability. Moreover, taking 40 K and 6 Li atom–molecule conversion systems as examples, we give the unstable regions numerically. We also attempt to obtain the adiabatic criterion for this nonlinear system with classical adiabatic dynamics and study the adibaticity of the dark state with the adiabatic condition. 相似文献
9.
MA Song-She 《理论物理通讯》2010,54(3):521-523
A scheme is proposed to generate W state of N atoms trapped in a cavity, based on adiabatic passage along dark state. Taking advantage of adiabaticpassage, the atoms have no probability of being excited and thus the atomicspontaneous emission is suppressed. The scheme is simple. It does not needto adjust the interaction time accurately, and does not need to prepare thecavity field in one-photon state. Numerical simulation shows that thesuccessful probability of the scheme increases with the increasing of the atom number. 相似文献
10.
SONG Ming-Yu 《理论物理通讯》2011,56(5):837-844
We proposed an efficient scheme for constructing a quantum controlled phase-shift gate and generating the cluster states with rf superconducting quantum interference devices (SQUIDs) coupled to a microwave cavity through adiabatic evolution of dark eigenstates. During the operation, the spontaneous emission is suppressed since the rf SQUIDs are always in the three lowest flux states. Considering the influence from the cavity decay with achievable
experimental parameters, we numerically analyze the success probability and the fidelity for generating the two-SQUID maximally entangled state and the controlled phase-shift gate by adiabatic passage. 相似文献
11.
马宋设 《原子与分子物理学报》2009,26(6):1114-1118
提出一种方案制备W态,方案基于暗态绝热过程.制备过程中,所有原子都处于基态,光纤模保持在真空态,在一定条件下可以忽略腔场激发,因此,方案非常抗消相干.方案的另一个优点是:只要满足绝热条件,不必要精确调节相互作用时间.方案成功的几率随原子数的增加而增加. 相似文献
12.
Quantum adiabatic evolution describes the dynamical evolution of a slowly driven Hamiltonian. In most systems undergoing spontaneous symmetry-breaking transitions, the symmetry-protected quantum adiabatic evolution can still appear, even when the two lowest eigenstates become degenerate. Here, a general derivation to revisit the symmetry-dependent transition and the symmetry-dependent adiabatic condition (SDAC) is given. Further, based on the SDAC, an adiabatic-parameter-fixed sweeping scheme is used for achieving fast adiabatic evolution, which is more efficient than the linear sweeping scheme. In the limit of small adiabatic parameter, an analytic inequality is obtained for the ground state fidelity only dependent on the adiabatic parameter. The general statements are then demonstrated via two typical systems. Besides, the robustness of the symmetry-dependent adiabatic evolution against weak symmetry-breaking sources is studied. The findings can be tested via the techniques in quantum annealing and may provide promising applications in practical quantum technologies. 相似文献
13.
马宋设 《原子与分子物理学报》2010,27(1)
提出一种方案制备W态,方案基于暗态绝热过程。制备过程中,所有原子都处于基态,光纤模保持在真空态,在一定条件下可以忽略腔场激发,因此,方案非常抗消相干。方案的另一个优点是:只要满足绝热条件,不必要精确调节相互作用时间。方案成功的几率随原子数的增加而增加。 相似文献
14.
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
15.
基于El-Nabulsi动力学模型,研究了小扰动作用下Birkhoff系统Noether对称性的摄动与绝热不变量问题.首先,将El-Nabulsi提出的在分数阶微积分框架下基于Riemann-Liouville分数阶积分的非保守系统动力学模型拓展到Birkhoff系统,建立El-Nabulsi-Birkhoff方程;其次,基于在无限小变换下El-Nabulsi-Pfaff作用量的不变性,给出Noether准对称性的定义和判据,得到了Noether对称性导致的精确不变量;再次,引入力学系统的绝热不变量概念,研究El-Nabulsi动力学模型下受小扰动作用的Birkhoff系统Noether对称性的摄动与绝热不变量之间的关系,得到了对称性摄动导致的绝热不变量的条件及其形式.作为特例,给出了El-Nabulsi动力学模型下相空间中非保守系统和经典Birkhoff系统的Noether对称性的摄动与绝热不变量.以著名的Hojman-Urrutia问题为例,研究其在El-Nabulsi动力学模型下的Noether对称性,得到了相应的精确不变量和绝热不变量. 相似文献
16.
Implementation of quantum search scheme by adiabatic passage in a cavity--laser--atom system 下载免费PDF全文
This paper proposes a scheme for implementing the adiabatic quantum
search algorithm of different marked items in an unsorted list of
N items with atoms in a cavity driven by lasers. N identical
three-level atoms are trapped in a single-mode cavity. Each atom is
driven by a set of three pulsed laser fields. In each atom, the same
level represents a database entry. Two of the atoms are marked
differently. The marked atom has an energy gap between its two
ground states. The two different marked states can be sought out
respectively starting from an initial entangled state by controlling
the ratio of three pulse amplitudes. Moreover, the mechanism, based
on adiabatic passage, constitutes a decoherence-free method in the
sense that spontaneous emission and cavity damping are avoided since
the dynamics follows the dark state. Furthermore, this paper extends
the algorithm with m (m>2) atoms marked in an ideal situation.
Any different marked state can be sought out. 相似文献
17.
This paper presents and implements a specified partial adiabatic search algorithm on a quantum circuit. It studies the minimum energy gap between the first excited state and the ground state of the system Hamiltonian and it finds that,in the case of M = 1,the algorithm has the same performance as the local adiabatic algorithm. However,the algorithm evolves globally only within a small interval,which implies that it keeps the advantages of global adiabatic algorithms without losing the speedup of the local adiabatic search algorithm. 相似文献
18.
Exact invariants and adiabatic invariants of dynamical system of relative motion 总被引:1,自引:0,他引:1 下载免费PDF全文
Based on the theory of symmetries and conserved quantities, the exact invariants and adiabatic invariants of a dynamical system of relative motion are studied. The perturbation to symmetries for the dynamical system of relative motion under small excitation is discussed. The concept of high-order adiabatic invariant is presented, and the form of exact invariants and adiabatic invariants as well as the conditions for their existence are given. Then the corresponding inverse problem is studied. 相似文献
19.
Superposition of Fock states via adiabatic passage in a coupled four-level atom-cavity system 下载免费PDF全文
We have investigated the behaviour of an atom-cavity system via a stimulated Raman adiabatic passage technique in a four-level system, in which two dark states are present. We find, because of the coherent control field, that a superposition of Fock states can be prepared, even when the cavity is initially not in its vacuum state. This method provides a way to generate arbitrary quantum states of a cavity field. 相似文献
20.
提出了利用Efimov共振辅助的受激拉曼绝热通道(ER-STIRAP) 过程实施超冷原子向异核四聚物分子A3B转化的理论方案, 得到了转化过程中中间态分别为同核Efimov三聚物A3和 异核Efimov三聚物A2B两种途径下系统的暗态解, 证实了ER-STIRAP技术对超冷异核四聚物分子A3B合成的可行性和有效性. 研究了外场参数, 包括缔合光脉冲的强度、脉宽、磁耦合强度及其失谐量等对A3B形成的影响. 对两种不同中间态的转化途径进行比较发现, 与中间态为异核Efimov三聚物A2B的途径相比, 经历中间态为同核Efimov三聚物A3的途径时系统实现最终四聚物分子A3B的产率更高. 另外, 还讨论了系统内禀的非线性和中间态的自发辐射损失对异核四聚物分子合成的影响. 相似文献