Wigner function of the thermo number states

Based on thermo field dynamics (TFD) and using the thermo Wigner operator in the thermo entangled state representation we derive the Wigner function of number states at finite temperature (named thermo number states). The figure of Wigner function shows that its shape gets smoothed as the temperature rises, implying that the quantum noise becomes larger.     

广义热化算符与单模纯量热化效应

根据温度效应与动力学压缩效应在数学处理上的相似性,将热化算符与压缩算符推广为一般的广义热化算符,通常的双模压缩态成为实空间的热场态,其中任何一个模的光子分布都具有经典的Bose-Einstein热场分布的特点（单模纯量子热化效应）。     

类克尔介质中原子布居数的演化和偶极压缩效应

研究了一个两能级原子处于充满类克尔介质的高Ｑ腔里与单模辐射场多光子相互作用的系统中，原子能级布居数的时间演化特性以及原子的偶极压缩效应，着重讨论了类克尔介质与单模辐射场作用的耦合强度ｘ和失谐量Δ对原子系统行为的影响。     

New Operator Realization of Superoperators and Its Application in Quantum Information Theory

By exposing deficiency of the usual superoperators that have no explicit operator-expression in quantum information theory we introduce thermo entangled state representation to endow each of these superoperators a definite operator-expression in an enlarged space in which one mode is a fictitious. This helps us to directly derive the role of exponential of superoperators and the solutions of some master equations.     

Expectation Value Theorem for Thermo Vacuum States of Optical Chaotic Field and Negative-Binomial Field

For the density operator (mixed state) describing chaotic light and negative-binomial field there exist the corresponding thermal vacuum state (pure state) in the real-fictitious space. Using the method of integration within ordered product of operators we find the expectation value theorem in these two thermo vacuum states respectively. The thermal average theorem of translation operator is also deduced. Application of the new thermo vacuum state in calculating photon number disturibution and fluctuation and thermal average is presented.     

Exact solution for the thermo Jaynes--Cummings model

Based on the construction of supersymmetric generators, we use the Lewis--Riesenfeld invariant method to deduce the exact and explicit eigen-energy spectrum with the time-dependent thermo Jaynes--Cummings model. One of the advantages of this approach is that it can transform the hidden form, related to the chronological product, of the time evolution operator into an explicit expression. Moreover, the dynamical and statistics properties of physical quantities are obtained for the given initial states in the thermo Jaynes--Cummings system.     

New Operator Realization of Superoperators and Its Application in Quantum Information Theory

By exposing deficiency of the usual superoperators that have no explicit operator-expression in quantum information theory we introduce thermo entangled state representation to endow each of these superoperators a definite operator-expression in an enlarged space in which one mode is a fictitious. This helps us to directly derive the role of exponential of superoperators and the solutions of some master equations.     

热场动力学理论中的Husimi分布函数及Wehrl熵的研究

利用量子相空间技术和信息熵理论,研究了热场动力学理论中量子纯态与相应混合态的Husimi分布函数及Wehrl熵的一致性问题.结果表明,热相干态与相应混合态的Husimi分布函数及Wehrl熵完全相同,支持了热场动力学理论.且热相干态的Wehrl熵与平移因子无关,故在热相干态中,量子系统的可观测量的量子涨落及不确定关系也与平移因子无关.     

不同材料参数薄板振动中的热力耦合效应

 利用有限Hankel变换法,导出了周界等温-弹性支撑圆薄板在激光束辐照下的轴对称耦合热弹性弯曲振动近似解;针对具有不同弹性模量和热膨胀系数的薄板进行了热力耦合和非耦合弯曲振动的解析和有限元计算与分析。结果表明：热力耦合效应使薄板振动的振幅和周期都有所减小,其程度与材料的性能参数（如弹性模量和热膨胀系数等）密切相关,材料弹性模量和热膨胀系数越大,板振动中的热力耦合效应就越明显。     

选区激光烧结瞬态温度场模拟与测试方法研究

采用有限元方法,考虑实际的边界条件和热物性参量的变化,对Al2O3覆膜陶瓷粉末的选区激光烧结过程瞬态三维温度场进行动态模拟.通过比色测温法对红外热成像系统的发射系数进行修正后,对选区激光烧结过程瞬态温度场进行测试.数值模拟和实测结果显示,两者吻合较好.     

Fluctuation of Mesoscopic RLC Circuit at Finite Temperature

We consider the fluctuation of mesoscopic RLC circuit at finite temperature since a resistance always produces Joule heat when the circuit is working. By virtue of the thermo field dynamics and the coherent thermo state representation we show that the quantum mechanical zero-point fluctuations of both charge and current increase with the rising temperature and the resistance value.     

非理想性参数在0.9～2.1区的氩等离子体物态方程研究

采用平面冲击压缩方法产生密度和温度都均匀的氩等离子体,根据辐射高温计记录和飞片速度的测定,通过阻抗匹配方法确定了氩等离子体的Hugoniot物态方程,等离子体温度在1.5 eV～2.6 eV范围,压力在0.2～0.8 GPa之间.计算表明,Saha-Debye-Hückel模型不适用于描述该密度区域的氩等离子体.本文采用Gryaznov模型的计算结果,测量值和理论计算结果符合较好.     

大功率半导体激光器温度控制技术研究

介绍了半导体激光器温度控制器的结构组成,给出了控制流过TEC电流幅度、方向和最大值的方法,利用PID实现精确温度控制。实验结果表明,控制的温度范围可达-15～＋60℃,温度稳定性为0．02℃。     

Number-Phase Quantization Scheme and the Quantum Effects of a Mesoscopic Electric Circuit at Finite Temperature

For L-C circuit, a new quantized scheme has been proposed in the context of number-phase quantization. In this quantization scheme, the number n of the electric charge q(q=en) is quantized as the charge number operator and the phase difference θ across the capacity is quantized as phase operator. Based on the scheme of number-phase quantization and the thermo field dynamics (TFD), the quantum fluctuations of the charge number and phase difference of a mesoscopic L-C circuit in the thermal vacuum state, the thermal coherent state and the thermal squeezed state have been studied. It is shown that these quantum fluctuations of the charge number and phase difference are related to not only the parameters of circuit, the squeezing parameter, but also the temperature in these quantum states. It is proven that the number-phase quantization scheme is very useful to tackle with quantization of some mesoscopic electric circuits and the quantum effects.     

Thermo Vacuum State for Describing the Density Operator of Photon-subtracted Squeezed Chaotic Light

For the density operator describing s?photon-subtracted squeezed chaotic light (PSSCL) we search for its thermo vacuum state (a pure state) in the real-fictitious space. We find that it reduces to a thermo vacuum state of squeezed chaotic light when s = 0, and to a thermo vacuum state of the optical negative binomial field when no squeezing. The new thermo vacuum state simplifies calculating photon number average, quantum fluctuation and Mandel’s Q parameter of PSSCL. Using the method of integration within ordered product (IWOP) of operators we also derive the normalization coefficient and explicitly analytical expressions of Wigner function for PSSCL.     

Thermo field dynamics in the treatment of the nuclear pairing problem at finite temperature

The use of the thermo field dynamics, in dealing with the study of nuclear properties at finite temperature, is discussed for the case of a nuclear Hamiltonian which includes a single-particle term and a monopole pairing residual two-body interaction. The rules of the thermo field dynamics are applied to double the Hilbert space, thus accounting for the thermal occupation of single-particle states, and to construct dual spaces, both for single-particle (BCS) and collective (RPA) degrees of freedom. It is shown that the rules of the thermo field dynamics yield to a temperature dependence of the equations describing quasiparticle and phonon excitations which is similar to the one found in the more conventional finite temperature Wick's theorem approach, namely: by dealing with thermal averages.     

Quantum Retrodiction in Non-Equilibrium Thermo Field Dynamics

The quantum retrodiction for open systems which obey the quantum Markovian dynamics is investigated by means of non-equilibrium thermo Field dynamics (NETFD) which can easily derive the retrodictive time-evolution generators. NETFD can formulate the quantum retrodiction for open systems in the same way as that for closed systems.     

Quantum Phase Properties of Photon Added and Subtracted Displaced Fock States

Quantum phase properties of photon added and subtracted displaced Fock states (and their limiting cases) are investigated from a number of perspectives, and it is shown that the quantum phase properties are dependent on the quantum state engineering operations performed. Specifically, the analytic expressions for quantum phase distributions and angular Q distribution as well as measures of quantum phase fluctuation and phase dispersion are obtained. The uniform phase distribution of the initial Fock states is observed to be transformed by the unitary operation (i.e., displacement operator) into non‐Gaussian shape, except for the initial vacuum state. It is observed that the phase distribution is symmetric with respect to the phase of the displacement parameter and becomes progressively narrower as its amplitude increases. The non‐unitary (photon addition/subtraction) operations make it even narrower in contrast to the Fock parameter, which leads to broadness. The photon subtraction is observed to be a more powerful quantum state engineering tool in comparison to the photon addition. Further, one of the quantum phase fluctuation parameters is found to reveal the existence of antibunching in both the engineered quantum states under consideration. Finally, the relevance of the engineered quantum states in the quantum phase estimation is also discussed.     

Temperature‐dependent Raman spectroscopy of BaTiO3 nanorods synthesized by using a template‐assisted sol–gel procedure

In the present work, multiphase polycrystalline BTO nanorods were synthesized using template‐assisted sol–gel deposition and their structural evolution was studied using thermo Raman spectroscopy, X‐ray diffractometry and high‐resolution transmission electron microscopy (HRTEM). In the BTO nanorods, the tetragonal phase was the dominant one, while both Raman and HRTEM indicated a coexistence with the high‐temperature hexagonal polymorph. This phase was stable across the whole of the investigated temperature range (from −95 °C to 200 °C). The investigated nanorods underwent a diffuse phase transition from tetragonal to cubic with respect to the temperature, whereas the final phase‐transition temperature was shifted to higher values compared to that expected for BTO. The low‐temperature orthorhombic‐to‐rhombohedral phase transition was also shifted to higher temperatures. These differences could be explained by the strain induced by the presence of hexagonal nanolamellas intergrown within the tetragonal nanocrystals. This result indicates that the temperature of the ferroelectric phase transition in polycrystalline BTO nanorods can be manipulated by introducing a stable hexagonal phase. Copyright © 2012 John Wiley & Sons, Ltd.     

位置涨落对DNA分子电子结构的影响

在紧束缚模型基础上，研究了位置涨落对碱基对周期排列的有序DNA分子的能带结构和电子态的影响，并分析了DNA分子的导电性.计算发现：随涨落的增强，带隙变小，同时，电子态倾向于局域化.室温下DNA分子的导带底电子态将呈现出较强的局域行为，因此，即使对有序排列的DNA分子，带输运理论在室温下也可能不再适用. 关键词： DNA 涨落 带隙 电子态