共查询到20条相似文献,搜索用时 31 毫秒
1.
本文提出了半导体中过渡元素杂质的一个简单模型,用格林函数方法计算了硅中替代和间隙原子产生的杂质能级和波函数。发现两者的性质有很大的差别。替代原子只有当d原子能级Vd低于价带顶时才能产生杂质能级。它的波函数主要是悬键态,当能级靠近导带边时变成正键态。间隙原子只有当Vd高于价带顶时才能产生杂质能级。它的波函数主要是中心原子d态,当能级靠近导带边时变成弱反键态。最后定性地说明了过渡元素杂质能级的化学趋势和一些实验事实。
关键词: 相似文献
2.
提出利用单个三粒子最大Greenberger-Horne-Zeilinger (GHZ)态或两个Einstein-Podolsky-Rosen (EPR)态作为量子信道确定性隐形传送任意三粒子GHZ态的两个方案,并将方案推广至隐形传送任意n(n≥4)粒子GHZ态的情况.讨论了量子信道受噪声影响时隐形传态的保真度.研究发现,当作为量子信道的单个三粒子最大GHZ态受到噪声影响时,隐形传态的保真度仅与量子信道的纠缠度有关,而当作为量子信道的两个EPR态受到噪声影响时,隐形传态的保真度不仅与量子信道的纠缠度有关,还与待传送态的纠缠度有关.所提出的方案具有节省量子信道纠缠资源的特点.
关键词:
隐形传态
三粒子Greenberger-Horne-Zeilinger态
量子逻辑门
保真度 相似文献
3.
Masashi Ban 《Optics Communications》1996,130(4-6):365-376
A scheme to generate the Fock state via a degenerate four-wave mixing and partial measurement is proposed. A conditional state of the signal mode of a degenerate four-wave mixer will be shown to reduce to the Fock state when the outcome of the measurement on the reference mode satisfies a certain condition. The photon number of the Fock state is distributed when the measurement is repeated many times. Conditioning for the quantum state of the signal mode is carried out by the photon counting measurement on the reference mode whose input state is assumed to be the vacuum. The phase coherence of the conditional signal state is also considered. Furthermore conditioning for the signal mode by means of heterodyne and homodyne detections are briefly considered. 相似文献
4.
用Bonn势和考虑强子质量Brown Rho(BR)标度规则修正,提出了改进的相对论平均场有效模型,由核物质的基态性质确定模型参数后,将该模型用来研究热密核物质系统的状态方程. 相似文献
5.
We consider the adiabatic limit of Hadamard states for free quantum Klein–Gordon fields, when the background metric and the field mass are slowly varied from their initial to final values. If the Klein–Gordon field stays massive, we prove that the adiabatic limit of the initial vacuum state is the (final) vacuum state, by extending to the symplectic framework the adiabatic theorem of Avron–Seiler–Yaffe. In cases when only the field mass is varied, using an abstract version of the mode decomposition method we can also consider the case when the initial or final mass vanishes, and the initial state is either a thermal state or a more general Hadamard state. 相似文献
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与两等同Bell态纠缠原子相互作用光场的量子场熵 总被引:2,自引:1,他引:1
利用全量子理论,并通过数值计算,研究了初始处于Fock态的单模光场与两等同双能级纠缠原子单光子共振相互作用过程中单模光场量子场熵的时间演化特性.结果发现:当两原子初始处于第一种Bell态时,光场量子场熵的时间演化周期为π/g2(2n+1);随着初始光强的增大,光场与原子之间的量子纠缠现象减弱;特别是当时间t为演化周期的整数倍时,场-原子系统处于退纠缠状态.当两原子初始处于第二种Bell态时,光场量子场熵不随时间变化,恒为零.当两原子初始分别处于第三种和第四种Bell态时,光场量子场熵的时间演化曲线呈现不等幅周期振荡现象;并且随着初始光场光子数的增加,光场量子场熵的振荡周期逐渐增大,但振荡幅值逐渐减小. 相似文献
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提出双环单模掺铒光纤激光器激光混沌耦合反馈相移控制方法和物理模型,利用耦合器将系统的输出量反馈到系统中,选取适当的反馈系数,并在反馈通道上加入相移控制器PC控制反馈光的相移,通过对反馈系数和反馈光相移的控制,实时、动态、有效地控制激光混沌到稳定态和周期态;分析了系统输出状态随着控制参数变化的演化规律,控制参数的变化可以使得系统的输出产生丰富的有一定规律性的激光动力学现象;讨论了混沌被控制到单周期态时系统输出的振荡周期的变化规律与控制量的关系。 相似文献
10.
电接触法是测试超声电机定转子接触状态的有效方法,但目前该方法主要用来研究电机堵转时的定转子接触状态,没有进行电机旋转时的接触状态的测试。针对该问题,对电接触法进行改进,使之可以测试电机旋转时的接触状态。基于改进后的电接触法分别对超声电机堵转和空载情况下定转子相对接触长度进行测试。结果表明,空载时定转子相对接触长度要小的多,与堵转时的最大差值约为36%。说明负载对超声电机接触状态有不可忽视的影响。最后,基于黏弹性接触模型对电机空载时定转子接触状态进行仿真计算,结果与实验值有很好的一致性,表明改进后的电接触法可有效的测试电机动态接触状态。 相似文献
11.
Noisy teleportation of qubit states via the Greenberger-Horne-Zeilinger state or the W state 下载免费PDF全文
The effects of distributing entanglement through the amplitude
damping channel or the phase damping channel on the teleportation of
a single-qubit state via the Greenberger--Horne--Zeilinger state and the W
state are discussed. It is found that the average fidelity of
teleportation depends on the type and rate of the damping in the
channel. For the one-qubit affected case, the
Greenberger--Horne--Zeilinger state is as robust as the W state,
i.e., the same quantum information is preserved through
teleportation. For the two-qubit affected case, the W state is more robust
when the entanglement is distributed via the amplitude damping
channel; if the entanglement is distributed via the phase damping
channel, the W state is more robust when the noisy parameter is
small while the Greenberger--Horne--Zeilinger state becomes more
robust when it is large. For the three-qubit affected case, the
Greenberger--Horne--Zeilinger state is more robust than the W
state. 相似文献
12.
研究了外加脉冲信号对介观RLC电路量子态变化的影响.结果表明:当电路参数一定时,通过控制脉冲信号参数的变化可以调节介观电路量子态变化的跃迁概率;而当脉冲信号宽度是某个最小量的整数倍时,系统的量子态保持不变.最小量的值与电路参数有关,但与脉冲信号幅度无关.电阻越大,保持系统量子态稳定的脉冲信号最小宽度则越宽.
关键词:
介观RLC电路
脉冲信号
量子态 相似文献
13.
Interference between the two Bose-Einstein condensates with collision and dissipation is investigated. It is found that when the two condensates are initially in the coherent state, the
interference intensity is affected by the collision and dissipation, but for the initial Fock state, it is only related to the dissipation. Whether the initial state is in the coherent
state or in a Fock state, the fidelity time has nothing to do with
collision. For the initial coherent state, the fidelity loss rate
is zero, but for the initial Fock state, it is determined by the
initial particle number of the two condensates and dissipation. 相似文献
14.
The evolution of the short-range structural signature of the Ir4+ dimer state in CuIr2S4 thiospinel has been studied across the metal-insulator phase transitions as the metallic state is induced by temperature, Cr doping, and x-ray fluence. An atomic pair distribution function (PDF) approach reveals that there are no local dimers that survive into the metallic phase when this is invoked by temperature and doping. The PDF shows Ir4+ dimers when they exist, regardless of whether or not they are long-range ordered. At 100 K, exposure to a 98 keV x-ray beam melts the long-range dimer order within a few seconds, though the local dimers remain intact. This shows that the metallic state accessed on warming and doping is qualitatively different from the state obtained under x-ray irradiation. 相似文献
15.
本文利用基于密度泛函理论的第一性原理方法计算了钆(Gd)掺杂氧化锌(ZnO)纳米线的磁耦合特性. 讨论了两个Gd原子替换ZnO纳米线中不同位置Zn原子的各种可能情况. 计算发现, ZnO中掺杂的Gd原子处于相邻的位置时它们之间的相互作用是铁磁性的, 并且体系的铁磁性可以通过注入合适数目的电子来得到加强. 同时发现Gd掺杂ZnO纳米线后s-f耦合作用变得显著, 使得体系的铁磁性变得更加稳定, 这也是Gd掺杂ZnO纳米线呈现铁磁性的原因. 这些结果为实验上发现的Gd掺杂ZnO纳米线呈铁磁性提供了理论依据. 相似文献
16.
Lionel Tenemeza Kenfack Martin Tchoffo Lukong Cornelius Fai 《Physics letters. A》2018,382(39):2805-2818
We consider a system of three uncoupled entangled qubits undergoing a decoherence process (DP) induced by a classical environmental noise portrayed by a Gaussian distributed fluctuating field with either Ornstein–Uhlenbeck (OU) or Gaussian (G) autocorrelation function. The impacts of such a DP on the entanglement of the qubits are analyzed in detail when they are initialized either in the GHZ- or W-type states and interact with the fluctuating field in three different scenarios namely, common, independent and mixed environment(s). We found that: (i) the way the qubits interact with the noise as well as their initial state play an important role towards the protection of entanglement; (ii) there are optimal parameters which permit to delay or totally avoid the disentanglement of the qubits; (iii) irrespective of the qubit-noise coupling (QNC) scenario and the initial prepared state considered, the OU noise is more injurious to the survivorship of entanglement than the G one. Specifically, we show that, irrespective of the QNC scenario and the character of the noise considered, the DP disentangles the qubits more quickly when they are initialized in the W-type states than in the GHZ-type one. Furthermore, we show that when the initial state of the qubits is considered to be a W-type state, the disentanglement occurs more rapidly in the common environment (CE) scenario followed by the mixed environments (MEs) scenario than in the independent environments (IEs) one. However, the situation is completely reversed when a GHZ-type state is considered. 相似文献
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18.
Nagler J Hauert C Schuster HG 《Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics》1999,60(3):2706-2709
In order to gain insight into the nature of self-organized criticality (SOC), we present a minimal model exhibiting this phenomenon. In this analytically solvable model, the state of the system is fully described by a single-integer variable. The system organizes in its critical state without external tuning. We derive analytically the probability distribution of durations of disturbances propagating through the system. As required by SOC, this distribution is scale invariant and follows a power law over several orders of magnitude. Our solution also reproduces the exponential tail of the distribution due to finite size effects. Moreover, we show that large avalanches are suppressed when stabilizing the system in its critical state. Interestingly, avalanches are affected in a similar way when driving the system away from the critical state. With this model, we have reduced SOC dynamics to a leveling process as described by Ehrenfest's famous flea model. 相似文献
19.
The phase properties of the superposed squeezed states are studied. The superposed squeezed states are obtained by inserting
two squeezers in a Mach-Zehnder interferometer one for each arm. The visibility of the states as a measure of the coherence
of the generated photons in the nonlinear interferometer is analyzed. And the mean-square phase fluctuations are also considered
to analyze the phase properties of the superposed squeezed states. The quantities are obtained as a function of gain and the
input phase, when the amplified input is a coherent state, a number state, a thermal state, a displaced number state, or a
coherent thermal state. 相似文献
20.
采用线性组合算符法和幺正变换法研究温度对抛物型量子阱中极化子基态能和基态结合能的影响. 通过理论推导得到极化子基态能和基态结合能的表达式. 结合量子统计力学中平均声子数的表达式, 得到极化子基态能量和基态结合能与温度的函数关系. 在不同温度下, 分别讨论了极化子基态能量和基态结合能与电子-声子耦合强度和阱宽的关系, 阱深取不同值时讨论了极化子基态能和基态结合能随温度的变化规律. 计算结果表明, 极化子的基态能量和基态结合能都是温度的递增函数. 相似文献