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1.
A method on how to take into account pump statistics and spontaneous atomic decays when calculating the photon-number distribution of lasers in photon-number representation is presented. The intracavity phonon-number and extracavity photocount distributions with binomial pump and spontaneous atomic decays are calculated. In two limit cases, the results of calculations transit respectively to the photon-number distributions of systems with common Poissonian pump and regular pump, and both with the spontaneous atomic decays being suppressed. 相似文献
2.
ZHENG ShiBiao 《理论物理通讯》2000,34(2):381-384
We propose a quantum nondemolition measurement of the photon-number distribution for a two-mode cavity field. In the scheme two sequences of two-level atoms interact dispersively with the respective cavity modes and resonantly with two classical fields, and then are detected continually. The field finally reduces to a two-mode Fock state. The probability of collapsing to a given Fock state is determined by the initial photon-number distribution. The scheme can be easily generalized to a field with N modes. 相似文献
3.
利用朗之万方程理论证明,在多单光子激光振荡的线性区域,泵浦统计、原子相干性及原子位相起伏可导致光子数压缩效应。 相似文献
4.
算符a^K本征态热迭加光场的光子数统计分布 总被引:1,自引:0,他引:1
利用密度矩阵方法,导出了光子湮没算符高次幂a^K(k≥2)本征态热迭加光场光子数统计分布的一般表达式,讨论了热噪声对非经典光场态光数统计分布振荡行为的影响。 相似文献
5.
For one-mode and multimode light, the photon-number tomograms of Gaussian quantum states are explicitly calculated in terms of multivariable Hermite polynomials. Positivity of the tomograms is shown to be a necessary condition for positivity of the density matrix. 相似文献
6.
Spectrally Adjustable Picosecond Dye Laser Pulses Generated with Nanosecond Nitrogen Lasers 总被引:2,自引:0,他引:2
Nguyen Dai Hung Pham Long Dinh Van Trung Nguyen Van Tien Le Hoang Hai Nguyen Ha 《Chinese Journal of Lasers》1995,4(5):385-392
SpectrallyAdjustablePicosecondDyeLaserPulsesGeneratedwithNanosecondNitrogenLasersNguyenDaiHung;PhamLong;DinhVanTrung;NguyenVa... 相似文献
7.
Measurement-device-independent quantum key distribution (MDI-QKD) is innately immune to all detection-side attacks. Due to the limitations of technology, most MDI-QKD protocols use weak coherent photon sources (WCPs), which may suffer from a photon-number splitting (PNS) attack from eavesdroppers. Therefore, the existing MDI-QKD protocols also need the decoy-state method, which can resist PNS attacks very well. However, the existing decoy-state methods do not attend to the existence of PNS attacks, and the secure keys are only generated by single-photon components. In fact, multiphoton pulses can also form secure keys if we can confirm that there is no PNS attack. For simplicity, we only analyze the weaker version of a PNS attack in which a legitimate user’s pulse count rate changes significantly after the attack. In this paper, under the null hypothesis of no PNS attack, we first determine whether there is an attack or not by retrieving the missing information of the existing decoy-state MDI-QKD protocols via statistical hypothesis testing, extract a normal distribution statistic, and provide a detection method and the corresponding Type I error probability. If the result is judged to be an attack, we use the existing decoy-state method to estimate the secure key rate. Otherwise, all pulses with the same basis leading to successful Bell state measurement (BSM) events including both single-photon pulses and multiphoton pulses can be used to generate secure keys, and we give the formula of the secure key rate in this case. Finally, based on actual experimental data from other literature, the associated experimental results (e.g., the significance level is 5%) show the correctness of our method. 相似文献
8.
Modulation induced low-frequency fluctuations (LFFs) of a semiconductor laser in the presence of optical feedback are investigated. LFFs are controlled to a synchronous oscillation when an appropriate modulation very close to the resonance frequency of the external cavity is applied to the injection current. The dependence of the frequency locking on the modulation frequency and depth is studied. 相似文献
9.
Phase-sensitive nonclassical properties of photon-added-then-subtracted coherent squeezed states
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We investigate the nonclassical properties of the photon-added-then-subtracted coherent squeezed state(PASCSS) via the sub-Poissonian statistics,the photon-number distribution,and the negativity of the Wigner function.It is found that the PASSCS is a superposition state of D(β)S(ζ)|0>,D(β)S(ζ)|1>,and D(β)S(ζ)|2>.We find that the Mandel Q parameter,the photon-number distribution,and the negative volume of the Wigner function of the PASCSS are all periodic functions of the compound φ-θ/2 with a period π involved with squeezing and displacement parameters. 相似文献
10.
Influence of Phase-Shift on Side-Mode Suppression Ratio in Fiber Grating External Cavity Semiconductor Lasers 总被引:2,自引:0,他引:2
He Xiaoying Huang Dexiu Li Wei 《International Journal of Infrared and Millimeter Waves》2005,26(8):1163-1173
Effects of system parameters on the side-mode suppression ratio of the fiber grating external cavity semiconductor laser are investigated by the numerical method, and the variation of the side-mode suppression ratio is discussed. It is found that an excellent anti-reflection coating provides the significant reduction of the variation due to the phase shift and the change of the internal cavity length. The laser with the low anti-reflection coating, the high coupling efficiency and the short cavity will exhibit the excellent side-mode suppression ratio. 相似文献
11.
From the normally ordered form of the density operator of a squeezed coherent state(SCS),we directly derive the compact expression of the SCS’s photon-number distribution(PND).Besides the known oscillation characteristics,we find that the PND is a periodic function with a period of π and extremely sensitive to phase.If the squeezing is strong enough,and the compound phase which is relevant to the complex squeezing and displacement parameters are assigned appropriate values,different oscillation behaviours in PND for even and odd photon numbers appear,respectively. 相似文献
12.
Quantum nondemolition measurement of photon—number distribution for a weak cavity field with resonant atoms
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We propose a quantum nondemolition measurement of the photon-number
distribution for a weak cavity field with no more than two photons. The
scheme is based on the resonant interaction of atoms with the cavity
field, and thus the required interaction time is much shorter than that using dispersive interaction. This is important in view of decoherence. Our scheme can also be used to generate even and odd coherent states for a weak cavity field with resonant atoms. 相似文献
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14.
纵向泵浦Tm:YAG激光器的理论研究 总被引:3,自引:0,他引:3
用准三能级系统速率方程对纵向泵浦Tm:YAG激光器的阈值,效率和激活介质最佳长度进行了计算和分析,讨论了温度对Tm:YAG激光器输出特性的影响。 相似文献
15.
A model of a memory system consisting of three neuron networks based on three interacting ring lasers–neurons is suggested. The neurons are considered as carriers of the Fermi–Pasta–Ulam recurrence spectra described within the framework of the modified Zabusky and Kruskal approach. The interaction of the FPU spectra is studied using both fluid and optical models. Physical evaluation shows that such a memory system does not have apparent quantity limits for the information stored. 相似文献
16.
LD侧面泵浦固体激光器泵浦光分布模拟 总被引:3,自引:1,他引:2
利用Gauss光束通过光学系统的变换规律,将激光二极管阵列发出的光作为Gauss光束处理.应用矩阵光学方法,解析分析与数值模拟相结合,给出了激光二极管阵列侧面泵浦棒状固体激光介质内泵浦光的强度分布.比较了侧面环绕激光二极管阵列数量不同时泵浦光分布的均匀性;以及考虑准直系统后,不同准直透镜焦距时,晶体内泵浦光半径的大小;同时针对泵浦光在晶体内聚焦时的情况进行了简单讨论.将半解析法与光线追迹法所得结果进行了比较,二者十分相近,但前者计算要简单得多. 相似文献
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18.
Nichols William T. Malyavanatham Gokul Henneke Dale E. O'Brien Daniel T. Becker Michael F. Keto John W. 《Journal of nanoparticle research》2002,4(5):423-432
Silver nanoparticles were produced by laser ablation of a continuously flowing aerosol of microparticles in nitrogen at varying laser fluences. Transmission electron micrographs were analyzed to determine the effect of laser fluence on the nanoparticle size distribution. These distributions exhibited bimodality with a large number of particles in a mode at small sizes (3–6-nm) and a second, less populated mode at larger sizes (11–16-nm). Both modes shifted to larger sizes with increasing laser fluence, with the small size mode shifting by 35% and the larger size mode by 25% over a fluence range of 0.3–4.2-J/cm2. Size histograms for each mode were found to be well represented by log-normal distributions. The distribution of mass displayed a striking shift from the large to the small size mode with increasing laser fluence. These results are discussed in terms of a model of nanoparticle formation from two distinct laser–solid interactions. Initially, laser vaporization of material from the surface leads to condensation of nanoparticles in the ambient gas. Material evaporation occurs until the plasma breakdown threshold of the microparticles is reached, generating a shock wave that propagates through the remaining material. Rapid condensation of the vapor in the low-pressure region occurs behind the traveling shock wave. Measurement of particle size distributions versus gas pressure in the ablation region, as well as, versus microparticle feedstock size confirmed the assignment of the larger size mode to surface-vaporization and the smaller size mode to shock-formed nanoparticles. 相似文献
19.
YANG Peng QIAN Feng HUANG Hong-Bin XIE Xia ZHANG Ya-Jun 《理论物理通讯》2006,46(1):141-148
We derive the dimensionless dynamic equations of two-photon lasers with A atomic level configuration by using the quantum Langevin equation method with the considerations of atomic coherence and injected classical fields. Then we analyze the stability and the chaotic dynamics of the two-photon laser by calculating the bifurcation diagram and the maximum Lyapunov exponent (MLE). Our results show that the Lorenz strange attractors and one-focus strange attractors can exist in this system, and the chaos can be induced or inhibited by the injected classical fields via Hopfbifurcations or crises, while the atomic coherence induces chaos via crises, and inhibit chaos via Hopf bifurcation or crises. 相似文献