Perturbation theory for radiation linewidth in circular Josephson-junction oscillators

The linewidth of the radiation from the Josephson ring oscillator under the influence of an external field is predicted by a new perturbation analysis which is an imporvement of an earlier kink model. The linewidth is due to background oscillations rather than kink velocity fluctuations.     

Entangling macroscopic oscillators exploiting radiation pressure

It is shown that radiation pressure can be profitably used to entangle macroscopic oscillators like movable mirrors, using present technology. We prove a new sufficient criterion for entanglement and show that the achievable entanglement is robust against thermal noise. Its signature can be revealed using common optomechanical readout apparatus.     

Investigations on optically controlled millimeter wave Gunn oscillators

There is a growing interest in optically controlled millimeter wave oscillators. In this paper, we have investigated the external-circuit impedances of an optically controlled millimeter wave subharmonic Gunn diode oscillator, which is illuminated by GaAs/GaAlAs laser beam. The variation of the external-circuit impedances looking outward from the Gunn diode with respect to the optical injection plasma density are calculated based on a field analysis method. The results give some useful conclusions for optically controlled millimeter wave Gunn diode oscillator design. Experimentally an optical tuning frequency shift of 7MHz is achieved at W-band.     

Generalized expression for the natural width of the radiation spectrum of quantum oscillators

A simple method for calculating the linewidth of sources of stimulated coherent radiation caused by spontaneous noise and thermal fluctuations has been proposed in the framework of the two-level model of the active medium. An expression for the spectral width has been derived beyond the adiabatic approximation under an arbitrary relation between relaxation times in a self-sustained oscillation system, taking into account a finite spectral band of spontaneous radiation. The result is applicable for a wide class of coherent radiation sources.     

复杂辐射环境与武器装备试验评估

从业内普遍接受的电磁环境和武器装备电磁环境效应概念入手,提出了复杂辐射环境概念,解释了其内涵和意义;围绕军事问题,探讨了辐射环境的基本构成,从辐射来源上突出了水声环境、电磁环境、光学环境和核辐射环境四个剖面,从效应考虑又将其分解为自然辐射环境、自扰互扰辐射环境、背景辐射环境和威胁辐射环境四个剖面,指出了这些剖面的统计独立性;根据辐射环境结构、特性和信息承载效应,定义了辐射环境的复杂度,介绍了辐射对抗的基本原理;指出复杂辐射环境下武器装备试验与评估问题与传统问题一样,仍是个概率统计问题,并且给出了可按环境剖面进行分解的高效简便的试验与评估方法。     

Creation of hot radiation environments in laser-driven targets

A hot radiation environment, produced by maximizing laser-energy deposition into a small, high- "can," is a platform being developed for investigations of material properties under extreme conditions. In such small targets, almost doubling the laser energy results in only an incremental increase in the x-radiation flux, and almost no increase in the maximum achieved radiation temperature. That most of this additional laser energy is not deposited within the target is a direct consequence of laser-plasma interactions (LPI) outside of the target, which result in high-angle beams never entering the target late in the laser pulse. Accounting for these processes in the modeling results in quantitative agreement for the first time with experiments using very small cans. These findings have provided the scientific foundation for modifying the target geometry to mitigate the LPI and to achieve higher radiation temperatures.     

Deterministic controlled bidirectional remote state preparation in dissipative environments

It is a significant subject to explore effective quantum communication protocol and enhance the efficiency of the transmission process in noisy environments. In this paper, we investigate the bidirectional controlled remote preparation of an arbitrary single-qubit state in the presence of dissipative environments by using two EPR states as the entanglement source. We first construct the quantum circuit of our scheme by means of unitary matrix decomposition procedure, then the effects of the Markovian and non-Markovian environmental noises acting on the EPR states are considered through the analytical derivation and numerical calculations of the corresponding average fidelity. Moreover, we adopt two methods of weak measurement reversal (WMR) and detuning modulation to improve the average fidelity. Our results show that the average fidelity can be remarkably enhanced under appropriate conditions of the WMR strength and the detuning. Compared with the average fidelity behaviors in dissipative environments, it is also shown that the two methods for fidelity improvement are more efficient in the non-Markovian regime than in the Markovian regime.     

Intracavity frequency mixing in pulsed optical parametric oscillators for the efficient generation of continuously tunable ultraviolet radiation

Received: 4 May 1998/Revised version: 8 July 1998     

Nonlinear theory of channeling of radiation by a ribbon-shaped stream of cyclotron oscillators

The features of the nonlinear stage of radiation from transversely bounded, magnetically steered helical and rectilinear electron streams in a homogeneous medium and in vacuum are investigated theoretically under conditions of the normal and anomalous Doppler effects. The evolution of the transverse distribution of the radiated field is investigated, and the channeling effect of the electron stream is demonstrated. It is shown that in the radiation from a helical stream in a plasmalike medium a practically complete conversion of the energy of gyrational motion of the electrons into energy of electromagnetic oscillations can occur on account of the automatic fine tuning of the radiation angle. Zh. Tekh. Fiz. 69, 9–14 (January 1999)     

“Inversionless” stimulated emission of radiation by nonequilibrium ensembles of classical oscillators

We find classical analogs of quantum systems capable of stimulated emission of radiation in the absence of inversion. We show that cyclotron parametric instability in low-frequency modulation of the distribution function of resonant particles can amplify a bichromatic high-frequency field when amplification of each spectral component separately is impossible. We point to similar modes for a Cherenkov resonance and a model system with lumped parameters. Finally, we suggest using this effect for converting microwave radiation to a higher frequency. Zh. éksp. Teor. Fiz. 112, 1176–1196 (October 1997)     

相对论返波管超辐射产生与辐射的数值模拟研究

本文研究了相对论返波管产生X波段超辐射问题,产生中心频率为9.25 GHz的电磁脉冲,并在相对论返波管的输出端直接接入VLASOV辐射天线.提出将粒子模拟软件UNIPIC与自行研制的天线辐射模块相结合,实现超辐射现象微波的产生以及辐射的全过程模拟,并研究了输出功率随注入波脉冲以及填充稀有气体气压的变化.模拟结果表明,器件的峰值功率可以达到3.68 GW,瞬时效率超过100%,VLASOV天线在斜切角为20?时,天线的增益达到15.5 dB,在1 km处的功率密度可达到0.728 W/cm2.     

Planar oscillators for monolithic integration

Planar oscillators for monolithic millimeter-wave integrated circuits are considered, and a design based on a coplanar-waveguide resonator is described. Design data are obtained from simulation at 1 GHz. the resonator has a Q of 195 (50 when scaled to 100 GHz) and is mechanically tunable over a range of 12%. Combining this resonator with a Gunn diode, a model oscillator is obtained. Output is obtained quasi-optically through a transmitting antenna. Twenty one milliwatts of output at 4.5 GHz are obtained with high spectral purity. A 100 GHz monolithic planar oscillator based on this design should be possible.Research supported by the U.S. Army Research Office Contract DAAG29-79CO134, the National Science Foundation under Grant ECS-8116018, and the Joint Services Electronics Program (AFOSR Contract F49620-79-C-0178).     

Two models for josephson oscillators

Two exactly soluble quantum mechanical models for tunneling oscillators are discussed. The first one is a closed weak coupling system, in which the current is nondissipative. In the second, open strong coupling system the oscillation occurs as a reservoir driven phase transition of the first kind far from thermal equilibrium.     

Chimera states for coupled oscillators

Arrays of identical oscillators can display a remarkable spatiotemporal pattern in which phase-locked oscillators coexist with drifting ones. Discovered two years ago, such "chimera states" are believed to be impossible for locally or globally coupled systems; they are peculiar to the intermediate case of nonlocal coupling. Here we present an exact solution for this state, for a ring of phase oscillators coupled by a cosine kernel. We show that the stable chimera state bifurcates from a spatially modulated drift state, and dies in a saddle-node bifurcation with an unstable chimera state.     

Terahertz radiation of Bloch oscillators excited by an electromagnetic field in lateral semiconductor superlattices

The action of a strong high-frequency electromagnetic field on a lateral semiconductor superlattice is considered based on the quasi-classical electron transport theory in the self-consistent wave formulation. The theory predicts that a lateral superlattice can emit terahertz radiation wave trains, which are associated with periodic excitation of Bloch oscillations in the superlattice arising because of the development of transient processes in it in a variable self-consistent electric field. The conditions necessary for observing Bloch oscillator radiation were found. The spectral composition of radiation transmitted through the superlattice and the energy efficiency of frequency multiplication related to Bloch oscillator excitation were calculated.