双色反射技术在温度测量上的应用

本文以铁镍合金为例,介绍了一种测量金属表面温度的光学测量方法。试验以黑体为反射辐射源,采用FTIR光谱辐射计测量了试样在中温状态的发射辐射以及包含了黑体反射能量的有效辐射。通过建立包含反射辐射的方程组,并运用MATLAB内建的求根模型求解得到了试样表面温度。     

直立防波堤上部分反射的三阶双色双向水波理论

为充分克服以往直立防波堤上立波波浪力的内在局限性和刻画直立防波堤堤前的多色多向波,提出一种可包含经典二维长峰波解和三维单色单向短峰波解的部分反射的三阶双色双向水波理论,并从中推断出适用于高阶多色多向波系统的一项普适法则——偶数阶频率为零,奇数阶频率个数构成一等比数列.     

Quantum coherence in A-three-level system driven by bichromatic coupling field

<正>We present a theoretical study of quantum coherent effects in a A-three-level system with a strong bichromatic coupling field and a weak probe field.When one component of the strong bichromatic coupling field is resonant with a corresponding transition and the other is detuning with an integer fraction of the Rabi frequency of the resonant field, the absorption spectrum exhibits a series of symmetrical doublets.While two frequencies of the strong bichromatic coupling field are symmetrically detuned from the transition,the position and the relative intensity of the absorption peak are both affected by the coupling field intensity and detuning.An explanation of the spectrum is given in term of the dressed-state formalism.     

Analytical solutions for a doubly driven two-level atom

We have deduced analytical solutions of an energy level diagram of the doubly driven/dressed atom for a two-level atom exposed to a strong near-resonant bichromatic laser field in a special case, i.e., the bichromatic field with frequencies ω1 and ω2, and Rabi frequencies ?1 and ?2, in which the first coupling field of ?1 acts on the bare atomic levels, and then the resulting singly dressed states are driven by the second coupling field of ?2, thus resulting in the doubly dressed atom.We have measured the probe absorption spectra of a doubly driven two-level atom. The system consists of 52S1/2, F= 2 and 5~2P_(3/2), F'= 3 states of ~(87)Rb atoms in a magneto-optical trap(MOT) as well as the cooling/trapping beams and an additional coupling field. As for the spectroscopic properties of the doubly driven two-level atom, theoretical analytical solutions are in general agreement with the experimental spectrum as a whole.     

Cluster states prepared by using hot trapped ions

We propose a scheme for the preparation of one-dimensional and two-dimensional cluster states by using hot trapped ions. The scheme is based on the interaction between two ions and bichromatic radiation. The vibrational mode in our protocol is only virtually excited so that the system is insensitive to the thermal field. In addition, we only use two levels of ions as qubits and the successful probability may achieve 100%.     

Dynamical symmetry analysis of ionization and harmonic generation of atoms in bichromatic laser pulses

Recently the effect of the relative phase ? in a high‐intensity (～10¹⁴ W/cm²) two‐color (bichromatic) CW laser with frequencies ω and 2ω on the high‐order harmonic generation (HHG) was studied within the framework of the non‐Hermitian quantum mechanics (NHQM) [Phys Rev A 2004, 69, 043404/1]. Here we emphasize the study of symmetries in bichromatic HHG spectra within the framework of the conventional Hermitian QM, and in particular by taking the duration of the laser pulse into consideration (an effect that has not been included in the non‐Hermitian studies due to the time asymmetry problem in NHQM). The phase dependence of HHG and intense‐field ionization probability in a 1D Xe atom with symmetric field‐free potential and symmetric initial wave function were studied numerically and analytically. From simulations based on a single‐particle response it can be seen that the HHG spectra is symmetric with respect to inversion in the relative phase between the two colors ? only if ionization is forbidden in the system and the laser pulse is an adiabatic one. The HHG spectra is symmetric with respect to a π‐shift in ? whenever the laser pulse is an adiabatic one, either for bound or open (ionized) systems. The ionization probability is symmetric both to inversion or π‐shift in ?; the component probabilities (right‐ and left‐ionization probabilities) have the same ?‐dependence, up to a shift of π. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005     

Effects of thermal modulation on tunneling through a fluctuating barrier in presence of bichromatic electromagnetic field

The effects of thermal modulation on the tunneling dynamics of a particle moving in a bistable potential with a fluctuating barrier in the presence of bichromatic electromagnetic field are examined. This study brings to light various interesting features. While rate constant increases steadily with increasing fluctuation strength, a stochastic resonance‐like behavior is exhibited when tunneling rate is plotted as a function of barrier fluctuation frequency. The tunneling rate constant decreases with the increase in the differences of the strength of the two electric fields; on the other hand, it displays a maxima when plotted as a function of the ratio of the frequencies of the two fields. When the rate constant is plotted as a function of temperature, it increases and eventually settles down to a saturation value. We have also studied the effect of the phase difference between the two electric fields on the tunneling behavior in the presence of thermal modulation. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005     

Photodetachment dynamics from closed‐shell anions in the presence of a bichromatic field

I have studied the dynamics of photodetachment from closed‐shell anions in the presence of a two‐color (bichromatic) laser field. The electronic states of halide ions are modeled by a 1‐D Hamiltonian with a potential V(x) = ?V₀e. The two parameters V₀ and σ are fixed by requiring V(x) to reproduce the experimentally observed ground‐state ionization energy of the halide ions concerned. The potentials so generated are shown to support only one bound state in each case. The time‐dependent Fourier grid Hamiltonian method is used to follow the detachment dynamics with fairly high intensities of light. The environmental effects on the dynamics are sought to be modeled by allowing the well depth (V₀) to fluctuate randomly (V₀(t) = V₀[1 + ΔVR(t)]; R(t) randomly fluctuates between +1 and ?1 with time, when ΔV is fixed). The average detachment rate constants k_av are seen to increase with increase in the intensities of used bichromatic field. An alternative model potential, V(x) = ?V₀e^?σx, is also shown to yield similar results. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005     

The pump-probe approach to coherent backscattering of intense laser light from cold atoms

We present a new approach to near-resonant coherent backscattering of light from cold two-level atoms. In the dilute regime, where the distance between atoms is much larger than the laser wavelength, this approach is able to account for multi-photon scattering processes between many atoms through solutions of single-atom optical Bloch equations. We elaborate the method for double scattering from two atoms, and discuss the way of its extension for dilute, cold atomic clouds.