依赖强度耦合三光子过程下运动原子最佳熵压缩态的制备

为了研究三光子过程中原子与相干态耦合量子体系信息熵压缩随时间演化规律及原子最佳信息熵压缩态的制备,我们采用全量子理论,推导出运动原子与单模简并三光子依赖强度耦合量子体系的精确解;理论上给出制备原子最佳信息熵压缩态的充分及必要条件,并进行了数值模拟验证。研究结果表明：控制相干态场与原子作用时间,切断相干态场与原子的纠缠,选择二能级原子处于等权重相干叠加态,适当选取相干态场与原子的初始位相,可以制备出原子最佳量子信息熵压缩态;调节光腔中场模结构参量,能够得到连续的量子信息熵压缩态。该研究结果在多光子过程低噪声量子信息处理中具有一定意义。     

运动原子与光场依赖强度纠缠下最佳熵压缩态的制备和控制

运用量子信息熵理论,研究了运动二能级原子与光场依赖强度纠缠下最佳熵压缩态的制备和控制;比较了分别从基于信息熵不确定关系和海森堡不确定关系出发得出的结果;分析了制备原子最佳熵压缩态的充要条件,并进行了数值验证.考察了场模结构参数对最佳熵压缩态的影响.结果表明,信息熵压缩是对原子压缩效应的高灵敏量度;控制原子与场的相互作用时间,斩断原子和场的纠缠,选择原子的相干性,调节系统的相对位相可制备原子最佳熵压缩态;控制场模结构参数,可获得持续的原子最佳熵压缩态. 关键词： 依赖强度耦合 场模结构参数 最佳熵压缩态     

双光子过程中任意初态原子的信息熵压缩

运用量子信息熵理论研究了双光子过程中任意初态二能级原子与相干场相互作用的信息熵压缩，讨论了系统初态对原子信息熵压缩的影响. 并且比较了分别从基于信息熵不确定关系和海森伯不确定关系出发得出的结果. 结果表明通过选择适当初始的原子分布角，原子的混合度和相干场的位相角，可以分别控制原子信息熵压缩的偶极矩分量数、压缩频率、压缩幅度和压缩方向. 当原子反转为零时，基于海森堡不确定关系的方差压缩定义不再有效，而信息熵压缩实现了对原子压缩效应的高灵敏量度. 关键词： 二能级原子 双光子过程 信息熵压缩 方差压缩     

与二项式光扬相互作用的运动原子熵压缩

运用量子信息熵理论,研究了二项式光场与运动二能级原子相互作用过程中运动原子的信息熵压缩.讨论了不同的原子初态和场的有关参数对原子信息熵压缩的影响.结果表明:选择原子初态、场模结构、场调节参数及原子运动速度可以调控原子信息熵的压缩方向、偶极矩分量值和压缩周期;适当的选择参数可得到持续性的原子信息熵压缩.     

压缩相干态光场与Λ型三能级原子相互作用的纠缠特性

利用量子熵理论,研究了压缩相干态光场与Λ型三能级原子的量子纠缠随时间的演化特性.结果表明:光场与原子纠缠度依赖于初态原子能级叠加系数、光场压缩参量、相干态振幅参量及失谐量与耦合系数之比.当光场压缩参量增大时,光场与原子的最大纠缠度增大;若场失谐量与耦合系数之比增大,光场与原子纠缠则呈现周期性演化,系统呈现接近退纠缠;若场失谐量与耦合系数之比增大,光场与原子纠缠呈现周期性,场失谐量与耦合系数的比值足够大时,在一定时刻系统可处于稳定的最大纠缠态,且系统演化呈现周期性.     

压缩相干态光场与Λ型三能级原子相互作用的纠缠特性

利用量子熵理论,研究了压缩相干态光场与Λ型三能级原子的量子纠缠随时间的演化特性.结果表明：光场与原子纠缠度依赖于初态原子能级叠加系数、光场压缩参量、相干态振幅参量及失谐量与耦合系数之比.当光场压缩参量增大时,光场与原子的最大纠缠度增大;若场失谐量与耦合系数之比增大,光场与原子纠缠则呈现周期性演化,系统呈现接近退纠缠;若场失谐量与耦合系数之比增大,光场与原子纠缠呈现周期性,场失谐量与耦合系数的比值足够大时,在一定时刻系统可处于稳定的最大纠缠态,且系统演化呈现周期性.     

多光子Jaynes-Cummings模型中与Glauber-Lachs态相互作用原子的熵压缩

利用全量子理论,研究了多光子Jaynes-Cummings模型中与Glauber-Lachs态相互作用的混合态原子的信息熵压缩.讨论了相干平均光子数、热平均光子数、跃迁光子数、原子初态参量对原子信息熵压缩的影响.结果表明原子信息熵X分量没有熵压缩性质;相干平均光子数取值适当时,原子信息熵Y分量呈现熵压缩效应;热平均光子数、跃迁光子数会破坏原子信息熵Y分量的熵压缩效应;原子初态参量对原子信息熵Y分量能否呈现熵压缩效应没有决定性作用;伴随双光子跃迁时,原子的熵压缩因子的时间演化曲线呈现周期性.     

原子与双模相干强场依赖强度耦合多光子过程中纠缠量度与制备

给出了依赖强度耦合双模多光子过程Jaynes-Cummings模型的有效哈密顿量.在强场条件下,分别用量子约化熵和量子相对熵研究了上述模型中原子与场之间的纠缠以及双模相干场的模间纠缠演化.研究表明,这两类纠缠演化均与原子跃迁时吸收(或发射)的光子数k密切相关.同时,还揭示了双光子过程(k=1)和多光子过程(k≥2)中不同的纠缠特性.讨论了纠缠态的制备,制备了与时间无关的原子-场的Einstein-Podolsky-Rosen态和双模相干场的模间纠缠态.     

Kerr介质中相干态光场与耦合Λ型三能级原子作用原子信息熵的性质

利用全量子理论研究了相干态光场与耦合全同Λ型三能级原子相互作用过程中原子信息熵的演化特性.讨论了系统初始状态、失谐量和原子间偶极相互作用强度及克尔系数对原子信息熵演化特性的影响.数值计算结果表明:原子信息熵的性质主要决定于原子初态和场的平均光子数的大小.失谐量、原子间的耦合常数和克尔系数对原子信息熵的演化规律也有明显的影响.     

双模纠缠相干光场控制下双光子过程中有效二能级原子的信息熵压缩

根据量子信息理论,研究了与双模纠缠相干场相互作用双光子过程中有效二能级原子的信息熵压缩.讨论了场的初态对信息熵压缩的因影响,并且比较了分别从基于信息熵测不准关系和海森堡测不准关系出发得出的结果.结果表明:信息熵压缩的稳定周期性、压缩方向分别由场的平均光子数和方向角控制,场的纠缠度对信息熵压缩不产生影响.信息熵压缩实现了对原子压缩效应的高灵敏量度.     

与二项式光场相互作用的运动原子熵压缩

运用量子信息熵理论,研究了二项式光场与运动二能级原子相互作用过程中运动原子的信息熵压缩。讨论了不同的原子初态和场的有关参数对原子信息熵压缩的影响。结果表明：选择原子初态、场模结构、场调节参数及原子运动速度可以调控原子信息熵的压缩方向、偶极矩分量值和压缩周期;适当的选择参数可得到持续性的原子信息熵压缩。     

Preparation and control of atomic optimal entropy squeezing states for a moving two-level atom under control of the two-mode squeezing vacuum fields

From the viewpoint of quantum information,this paper studies preparation and control of atomic optimal entropy squeezing states(AOESS) for a moving two-level atom under control of the two-mode squeezing vacuum fields.Necessary conditions of preparation of the AOESS are analysed,and numerical verification of the AOESS is finished.It shows that the AOESS can be prepared by controlling the time of the atom interaction with the field,cutting the entanglement between the atom and field,and adjusting squeezing factor of the field.An atomic optimal entropy squeezing sudden generation in different components can alternately be realized by controlling the field-mode structure parameter.     

Information Entropy Squeezing for a Atom in Mode-Mode Competition System

The entropy squeezing properties for a two-level atom interacting with a two-mode field via two different competing transitions are investigated from a quantum information point of view. The influences of the initial state of the system and the relative coupling strength between the atom and the field on the atomic information entropy squeezing are discussed. Our results show that the squeezed direction and the frequency of the information entropy squeezing can be controlled by choosing the phase of the atom dipole and the relative competing strength of atom-field, respectively. We find that, under the same condition, no atomic variance squeezing is predicted from the HUR while optimal entropy squeezing is obtained from the EUR, so the quantum information entropy is a remarkable precision measure for the atomic squeezing in the considered system.     

Entropy squeezing for a V-type three-level atom interacting with a single-mode field and passing through the amplitude damping channel with weak measurement

The entropy squeezing of a V-type three-level atom interacting with a single-mode field and passing through the amplitude damping channel is investigated in detail. Our results show that when coupled to the single-mode field, the atom in appropriate initial states can not only generate obvious entropy squeezing but also keep in the optimal squeezing state,while passing through the amplitude damping channel, the atom can generate entropy squeezing under the control of the weak measurement. Besides, it is proved again that as a measurement method for atomic squeezing, the entropy squeezing is precise and effective. Therefore our work is instructive for experiments in preparing three-level system information resource with ultra-low quantum noise.     

Steady and optimal entropy squeezing for three types of moving three-level atoms coupled with a single-mode coherent field

The entropy squeezing properties of different types of moving three-level atoms coupled with a single-mode coherent field are studied. The influences of the moving velocity and initial states of the three-level atom on the entropy squeezing are discussed. The results show that, the entropy squeezing properties of the three-level atom depend on its initial state, moving velocity, and the type. A stationary three-level atom can not obtain a steady entropy squeezing whatever initial conditions are chosen, while a moving three-level atom can achieve a steady and optimal entropy squeezing through choosing higher velocity and appropriate initial state. Our result provides a simple method for preparing squeezing resources with ultra-low quantum noise of the three-level atomic system without additional any complex techniques.     

Entropy squeezing of a moving atom and control of noise of the quantum mechanical channel via the two-photon process

Based on the quantum information theory, we have investigated the entropy squeezing of a moving two-level atom interacting with the coherent field via the quantum mechanical channel of the two-photon process. The results are compared with those of atomic squeezing based on the Heisenberg uncertainty relation. The influences of the atomic motion and field-mode structure parameter on the atomic entropy squeezing and on the control of noise of the quantum mechanical channel via the two-photon process are examined. Our results show that the squeezed period, duration of optimal entropy squeezing of a two-level atom and the noise of the quantum mechanical channel can be controlled by appropriately choosing the atomic motion and the field-mode structure parameter, respectively. The quantum mechanical channel of two-photon process is an ideal channel for quantum information (atomic quantum state) transmission. Quantum information entropy is a remarkably accurate measure of the atomic squeezing.     

Generation and Preparation of the Sustained Optimal Entropy Squeezing State of a Motional Atom Inside Vacuum Cavity

Considering two two-level atoms initially in Bell state, we send one atom into a vacuum cavity while leaving the other outside, and consider the motion of atom inside the cavity. Using quantum information entropy squeezing theory, the time evolution of the entropy squeezing factor of atom inside the cavity is discussed for two cases, i.e., before and after performing rotation operations and measuring atom outside, the influences of the field mode structure and atomic motions on the atomic entropy squeezing are evaluated. It is shown that atom inside the cavity has no entropy squeezing phenomenon before operating atom outside the cavity. However, the optimal entropy squeezing phenomenon of period T = 2π/p emerges and constant entropy squeezing phenomenon can occur by adjusting rotation operation to R(π/4), and setting the field mode structure parameter 0 < p < 50. In particular, if choosing p > 50, a sustained optimal entropy squeezing state (SOESS) can be generated. We also present the schematic circuit diagram of preparation of SOESS. Our proposal provides a possible way for the initial decoherent state recovering into sustained maximal coherent superposition state of single atom in the quantum noise environment.