Quantum control theory is a new interdiscipline, which mainly studies the control of quantum states for systems in the microworld. First, quantum control theory is elicited through quantum information theory. Then the research contents and characteristics of quantum control theory and measurement theory in quantum control are expounded. Current research of quantum control theory is also summarized. And last, advanced research on quantum control theory is proposed.
The fifteen years' progress in the study of photonic crystals from being proposed to present was surveyed. The conception of photonic crystal and characteristics of inhibited spontaneous emission and localization of photons were described at first, then the research in theory, experiment and application were introduced respectively. The plane-wave expansion method, Green's function method, finite-difference time-domain method and transfer matrix method were described in theory research. In experiment research, fabrication method of photonic crystals was depicted;measurement method on characteristic parameter was depicted also. In application, photonic crystal fibers and waveguide, omnidirectional reflection microcavity, photonic crystal filters, hight extraction efficiency diode, nonlinearity optics effect in photonic crystals were decribed.
The combination of a novel direct-transition GaInNAs and AlAs/GaAs distributed Bragg reflector with high reflectivity are making up of a GaAs-based long wavelength (1.3~1.6μm) vertical-cavity surface-emitting laser, and the device are becoming the essential element in optical communication, network, and data treatment. We reviewed the long wavelength GaIn-NAs vertical-cavity surface-emitting laser from selection of material, epitaxial technology, and overseas and domestic development of GaInNAs vertical-cavity surface-emitting laser.
In this paper, we reviewed the progress of the three kinds of ultrashort fiber lasers. We pointer out that cladding pump technique is an effective way to improve the high pulse energy or high pulse power.
In SAR image most significant information of texture and region boundaries often appear in the middle and high frequency channels. Wavelet packet (WP) analysis decomposes the upper frequency bands as well as the lower ones. So it can achieve more accurate representation of the medium and high frequency information of SAR images. According to the " self-similarity " of the same subband, every subband is divided into subblocks of different importance and different size. Thus proper bit allocation and quantization can be implemented in subblocks. Meanwhile one can resort to image segmentation to achieve proper compression ratio in different image regions. The experimental results show the proposed method can suit the energy specialty of the SAR image. It can obtain higher PSNR and increase the image interpretability.
By using the general approximate representative of free standard deviation of phase difference for partially developed speckle fields produced by a weak diffuser, the free statistical distributions of phase difference of partially developed Gaussian speckle fields in the image fields for a two-lens imaging system have been analysed.
With the novel design of the diode-pumped thin disk laser high optical efficiency and good beam quality can be realized simultaneously. We consider the influence of the overlap of the pumped area of thin disk crystal and the cavity mode on the beam quality. Using the linear resonator and V-type resonator, we achieved M~2=1.15, 13.69 W and M~2=1.12, 13.85 W in CW output laser respectively. Then we study the intracavity frequency doubling in V-type resonator.
Based on the two coupled nonlinear Ginzburg-Landau equations, we demonstrated that by using the nonlinear polarization rotation as the mode-locking mechanism, the stretched pulse with high energies can be formed in a Yb~(3+)-doped fiber laser with the normal group-velocity dispersion. If this pulse is further compressed out of the cavity, a narrow pulse with high-energy can be obtained
Bragg mirror type of semiconductor saturable absorption mirror near 800 nm was made first time in China, by which we realized passive continuous wave modelocking for Arion laser pumped Ti-sapphire laser. Continuous wave modelocking series with frequency range from 100 MHz to 200 MHz were obtained.
A new high power, short duration time XeCl laser is realized in the proportion of HCl:Xe:He=0.12%:1%:98.88%, in order to prepare microstructure of quantum effect, molecular beam epitaxy, depositing film and analysis of output pulse profiles. Based on the analysis of gain coefficient and saturated state, with the increase of gas pressure and discharge voltage, the short duration time of laser pulse is obtained. The working pulse of XeCl laser is 18.65 ns. Calculated result indicated not only that the structure and the kinetics velocity equation of laser are suitable, but also which the duration time of pulse is shorter under unsatured process and is rising at satured state with growth of the pumped power. The new XeCl laser has the advantage of smaller heat affected zones, which has acted on the target material to produce the vapor plasma plume, carrying out more accurate nano-crystalline structures.
Based on the linear quantum theory and thermal reservoir model, we quantized the non-linear Schrdinger equation with fiber loss and derive the squeezing ratio formula. We analyzed the different coefficient of the loss which leads to the effect of the squeezed soliton. At the same time, we discuss the relation between the minimal squeezing ratio and the transmitted length along the fiber with the different soliton amplitude.
The two-atom dipole amplitude-squared squeezing in a system of a two-mode vacuum field interacting with two coupled atoms was studied. The influences of the initial atomic coherence and dipole-dipole interaction on the squeezing effect were discussed by numerical calculations.
The state function of the two-mode SU(1,1) coherent states field interacting with four-level atom added Kerr-like medium was derived. By using the state function it was studied that the influence of the Kerr effect and the initial light field intensity on the two-mode intensity correlation function, the Cauchy-Schwartz inequality, and the second-order correlation function for each mode. The results indicate that the influences of Kerr effects on the properties of the correlation on the correlation intensity between the two-mode on the bunching or antibunching effect of the two-mode SU(1,1) coherent states are obviously related to the initial intensity of the light field.
The density operator was induced via V-type atom interacting with a cavity-field through Raman process system in an amplitude damping cavity, and the properties of linear entropies for atom-field system for atom and for field in the system were investigated. The results show that the linear entropy of the system and atom are larger than zero except the initial time in a dissipative cavity. The values remain a certain degree after some time and increase with the increase of mean photon number. At t~~d, the atom is completely decoherent to the cavity. The field comes back to the initial pure state. But the atom is still in a mixed state. The larger the dissipation, the more rapid the linear entropies of the atom and system tend to the certain degree of mixture. And the larger the mean photon number, the more obvious the dissipation influence on the linear entropy.
The cavity field spectra for the nondegenerate two-photon Jayners-Cummings model with an additional Kerr-like medium were investigated. The results of the initial fields in pure number states were presented, and effects of self-phase modulation on the spectra structure were analyzed. It is found that the cavity field spectra are generally in two-peak structure for each mode. With the increase of the self-phase modulation effect of one mode, the peak-space of this mode get a raise and one peak rises and the other peak reduces for the both mode spectrum.
The field entropy squeezing properties in the nonlinear Jaynes-Cummings model are studied by means of quantum information entropy, and the influences of the nonlinear interaction of the Kerr medium with the model field and the initial state of atoms on the field entropy squeezing are discussed. It shows that the nonlinear interaction of the Kerr medium can lead to an increase in the squeezing depth. On the other the squeezing time and the squeezing depth increases with the increase of the atomic distribution angle.
The quantum fluctuations of charges and currents of mesoscopic capacitance coupled circuit with mutual inductance and power source were investigated by using canonical transformation and unitary transformation. The results show that the quantum fluctuations of charges and currents are independent of power source. When the components of the circuit are given, if the value of L~~1/L~~2 is very small or very large, the effect of coupling coefficient on quantum fluctuations of charges and currents are great. From no mutual inductance to having mutual inductance, the quantum fluctuation of charge of loop 2 and the quantum fluctuation of current of loop 1 are obvious. We can conclude that it play a very important role whether the mutual inductance exists or not.
It is studied systematically that generalized nonlinear unequal-power higher-power sum squeezing properties of generalized magnetic-field component in a new kind of three state superposition multimode Schrdinger-cat state light field which is composed of multimode complex conjugation imaginary coherent state, the contrary state of multimode complex conjugation imaginary coherent state, and multimode complex conjugation coherent state, by utilizing the theory of multimode squeezed states. It is found that the state is a new type of three state superposition multimode nonclassical light field, and under certain conditions, the generalized magnetic-field component in the state can display the effects of generalized nonlinear unequal-power higher-power sum squeezing which changes periodically.
The regularity of laser myocardium interaction was studied according to difusion approximation.The result indicates it can efectually reduce extent of myocardial thermal damage to enhance absorbance and reduce scattering. Hence far—infrared laser with long wavelength is a ideal choice for transmyocardial laser revascularization。
A concept of concentrated slowly decreasing dispersion management soliton was given. The propagation properties of the optical soliton in this system were studied from quasi nonlinear Schrdinger equation. It is shown the effect that the increase width of soliton pulse is reduced by the effect of the soliton pulse width is reduced by the fibers with slowly decreasing dispersion. When we choose right dispersion intensity number, we can get a very stable soliton propagation about the soliton pulse width, crest power and wave front.
The methods to solve Maxwell Equations have been researched and developed for almost 50 years. The finite element method now plays a dominant role in this field. But the spurious solutions always come up with the physical modes, though we developed many methods trying to eliminate them and find the edge element method. In this paper, the author analyzed the physical background and the numerical behavior of the spurious modes in conventional nodal finite element formulations, and give the direction of the numerical method to eliminate them. The first time, the author derive out the spurious source term which influence the quality of the physical modes, and counteracting this source using the new penalty term can improve the field profile of physical modes. We also give the numerical results of a rib waveguide and a directional coupler.
The relationship between Raman gain coefficient and Raman scattering section is deduced from Raman scattering probability. Based on the relationship, we get the curve of Raman gain coefficient and Raman frequency shift through numerical analysis and parameter adjustment, compare this curve with the curve of experiment, then the result in qualitative analysis is given.
Based on a spherical shell structure and the graded finite potential well model, the interface effects on the energy level shifts of bound states in a semiconductor quantum dot heterostructure were analyzed and calculated. It indicates that the interface effects are fairly significant when the quantum dots are in the strong confinement region.
Starting from temperature-measuring principle of three primary-colors, certain factors in the application of measuring flame temperature field was discussed. A convenient temperature-measuring formula was deduced and method to rectify measuring errors by calibration of system and relationship of three colorimetric temperatures was put forward. Through a designed measuring system, it measured temperature field of 200 MW boiler, and compared it with the measured data of dual spectrum thermometer. Results showed that the way described above is simple, the error s is no more than five percent, and has high measuring accuracy to satisfy the purpose of systematic burning diagnosis and real-time measurement as well as control, resulting in certain applied prospects in engineering.
Because of the atmospheric refraction and chromatic dispersion, the aiming path and the laser path are different, when the laser wavelength is different from the aiming light wavelength. This paper gave the model of atmospheric refraction and chromatic dispersion, and calculated the error of the aiming point and the laser beam when C02 laser attacks the target 10km distance, which is aimed with visible light and infrared independently.