作者机构：
[Liu, YY] Chinese Acad Sci, Wuhan Inst Phys & Math, State Key Lab Magnet Resonance & Atom & Mol Phys, Wuhan 430071, Peoples R China.;Cent China Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.;E China Normal Univ, Dept Phys, Shanghai 200062, Peoples R China.
通讯机构：
[Liu, YY] C;Chinese Acad Sci, Wuhan Inst Phys & Math, State Key Lab Magnet Resonance & Atom & Mol Phys, Wuhan 430071, Peoples R China.
关键词：
Asymmetric top free radicals;Molecular spectroscopy;Theoretical calculation
摘要：
This paper sketches out the effective Hamiltonian and basis set adopted in the spectroscopic calculation of asymmetric top free radicals, and details the machine implementation of the spectral analysis of asymmetric top free radicals, the design and usage of the program package. To demonstrate the application of this program, analyses have been performed on the far infrared laser magnetic resonance spectrum of (NO2)-N-14-O-16(I = 1) and the infrared diode laser spectrum of the v(3) band of PO2(I = 1/2) using the program.
作者机构：
[Hu, XM] Chinese Acad Sci, Shanghai Inst Opt & Fine Mech, Lab High Intens Opt, Shanghai 201800, Peoples R China.;Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
通讯机构：
[Hu, XM] C;Chinese Acad Sci, Shanghai Inst Opt & Fine Mech, Lab High Intens Opt, Shanghai 201800, Peoples R China.
摘要：
An anomalous linewidth is predicted to appear in a driven Mollow laser. The linewidth does not simply decrease as the laser intensity increases, but displays a local minimum and maximum. The maximal linewidth does not necessarily correspond to the maximal population in the excited lasing level but to the minimal population. Employing the dressed picture, we separate the population component of the linewidth from the coherence component. It is identified that quantum coherence is responsible for the linewidth anomaly. We isolate two irreversible pathways of population pumping and show that the coherence effects are ultimately determined by the population pumping through the two irreversible pathways.
作者机构：
[Hu, XM] Chinese Acad Sci, Shanghai Inst Opt & Fine Mech, Lab High Intens Opt, Shanghai 201800, Peoples R China.;Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
通讯机构：
[Hu, XM] C;Chinese Acad Sci, Shanghai Inst Opt & Fine Mech, Lab High Intens Opt, Shanghai 201800, Peoples R China.
摘要：
We present phase control of the fluctuation-induced bistability in the three-level Λ-type system where a weak, amplitude-fluctuating component and a strong coherent component are used as a control field. With the addition of the stochastic component, optical bistability can be produced even if detunings of the probe and control fields from corresponding atomic transition frequencies are equal;without the addition, the medium is transparent to the input light. Depending on the relative phase between the stochastic and coherent parts, bistability appears or disappears and the threshold intensity is raised or lowered.
作者机构：
[Hu, XM; Xiong, J; Peng, JS] Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
通讯机构：
[Hu, XM] H;Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
摘要：
A theoretical analysis of the spectral linewidth of V-type inversionless and Raman lasers is presented. First, we examine the effects of the atomic coherence between dressed states and the Autler-Townes splitting on the linewidth. It is demonstrated that near above threshold, the V inversionless laser has a narrower linewidth than that of the two-level laser. Instead of the dressed coherence, it is the Autler-Townes splitting that is responsible for the linewidth reduction though the dressed coherence determines the laser gain. Next, we explore the effects of the generated laser intensity on the linewidth. It is shown that the linewidths of the V inversionless and Raman lasers follow the usual 1/I decrease for smaller laser intensity I, but a slower decrease than 1/I for larger laser intensity. For the V Raman laser, even more surprisingly, with the laser intensity increasing, the linewidth appreciably increases as well. As a result, well above threshold, the V inversionless and Raman lasers may have a larger linewidth than that of the two-level laser. Finally, a comparison is made between the V lasers and the Λ lasers. It is found that the linewidth of the Λ inversionless laser shows a fast 1/I2 decay under optimum conditions.
作者机构：
[Hu, XM] Chinese Acad Sci, Shanghai Inst Opt & Fine Mech, Lab High Intens Opt, Shanghai 201800, Peoples R China.;Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
通讯机构：
[Hu, XM] C;Chinese Acad Sci, Shanghai Inst Opt & Fine Mech, Lab High Intens Opt, Shanghai 201800, Peoples R China.
摘要：
We study the statistical properties of a three-level laser where cascade coherent excitation as a two-step process is used as a coherent pump and a laser field is generated on the upper transition. It is shown that the laser intensity fluctuations are suppressed up to 50% below the shot noise limit and that the laser linewidth is reduced below the Schawlow-Townes formula by more than one order of magnitude of the laser intensity. By transforming to the picture dressed by the coherent field on the upper transition, we identify a transfer of the lower coherent excitation to be responsible for the quantum noise reduction. Cascade coherent excitation turns out to be a new way in which one can create a pathway for recycling of active electrons and regularization of laser excitation process. The conditions for the physical realization of the Raman scheme (Ritsch et al 1992 Europhys. Lett. 19 7) as a limiting case is discussed.
作者机构：
[Wang, EK; Zhang, HZ; Xiao, J] Huazhong Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.
通讯机构：
[Wang, EK] H;Huazhong Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.
摘要：
Based on fully finite temperature field theory we investigate the radiation probability in the bremsstrahlung process in thermal QED. It turns out that the infrared divergences resulting from the emission and absorption of the real photons are cancelled by the virtual photon exchange processes at finite temperature. The full quantum calculation results for soft photon radiation coincide completely with those obtained in the semiclassical approximation. In the framework of thermofield dynamics it is shown that the bremsstrahlung radiation in thermal QED is a coherent state and its quasi-classical behaviour leads to the above coincidence.
摘要：
Experimental investigation of a novel differential velocity modulation laser spectroscopy is reported and demonstrated with the spectra of n
2
+
A2Dm -X2Ó
g
+
Meinel system. The S/N ratio excesses 500· ·1, about 60 times higher than that with the traditional non-differential technique. With this technique, we obtained the high-resolution electronic absorption spectra of A2D-X2Ó+ (1, 0) vibration-al band of CS+ for the first time. It is confirmed that this technique will be a powerful method and receive wide application in studies of new molecular ions.
作者机构：
[Wu, Shuang-Qing; Cai, Xu] Institute of Particle Physics, Huazhong Normal University, Wuhan 430079, China
通讯机构：
[Wu, S.-Q.] I;Institute of Particle Physics, , Wuhan 430079, China
摘要：
The Hawking effect of Dirac particles in a variable-mass Kerr spacetime is investigated by using the method of the generalized tortoise coordinate transformation. The location and the temperature of the event horizon of the non-stationary Kerr black hole are derived. It is shown that the temperature and the shape of the event horizon depend not only on the time but also on the polar angle. However, our results demonstrate that the Fermi-Dirac spectrum displays a residual term which is absent from that of the Bose-Einstein distribution.
作者机构：
[Cai, X; Wu, SQ] Huazhong Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.
通讯机构：
[Wu, SQ] H;Huazhong Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.
摘要：
The Hawking effect of Dirac particles in a variable-mass Kerr spacetime is investigated by using the method of the generalized tortoise coordinate transformation. The location and the temperature of the event horizon of the non-stationary Kerr black hole are derived. It is shown that the temperature and the shape of the event horizon depend not only on the time but also on the polar angle. However, our results demonstrate that the Fermi-Dirac spectrum displays a residual term which is absent from that of the Bose-Einstein distribution.
