On reconstructing photon statistics by on/off detectors: Toward the multi-partite case

The propagation of pulses of the pump and its second harmonic in a quadratically nonlinear medium whose linear properties are characterized by a negative refractive index at the pump frequency and by a positive refractive index at the harmonic frequency is considered theoretically. In the case of a low intensity of the interacting waves, the pump and second-harmonic pulses propagate in the opposite directions, but sufficiently powerful pulses can form a simulton—a solitary two-frequency wave propagating in a certain direction as a single whole. Solutions to a set of equations are found which describe the steady-state propagation of a solitary wave and of a nonlinear periodic (cnoidal) wave.     

Evolution of Classical and Quantum States in the Groupoid Picture of Quantum Mechanics

The evolution of states of the composition of classical and quantum systems in the groupoid formalism for physical theories introduced recently is discussed. It is shown that the notion of a classical system, in the sense of Birkhoff and von Neumann, is equivalent, in the case of systems with a countable number of outputs, to a totally disconnected groupoid with Abelian von Neumann algebra. The impossibility of evolving a separable state of a composite system made up of a classical and a quantum one into an entangled state by means of a unitary evolution is proven in accordance with Raggio’s theorem, which is extended to include a new family of separable states corresponding to the composition of a system with a totally disconnected space of outcomes and a quantum one.     

Cumulants and moments

We introduce a ¹-algebra of terminating sequences. The set of normalized linear functionals on this algebra is then equipped with a quasi-multiplication and thus with a multiplication. A state corresponds to a sequence of moments. With it we associate its sequence of cumulants. The quasi-multiplication relates cumulants and moments in a very easy way. We give necessary and sufficient conditions for a sequence to be a sequence of moments and necessary and sufficient conditions for a sequence to be a sequence of cumulants.     

Measuring Light Field of Light Source with High Directional Resolution Using Mirrored Ball and Pinhole Camera

This paper presents a method of measuring a light field of a light source with high directional resolution using a mirrored ball and a pinhole camera. The light field describes a spatial and directional distribution of radiances from the light source. The directional distribution is expanded by a reflection on the mirrored ball, and the radiances are measured by a charge-coupled device (CCD) camera with a pinhole lens. The light source is laterally moved by a robot arm to measure the directionally expanded light field, and each pixel on a CCD can obtain the radiances from the light source through the pinhole lens with high directional resolution. The light field is estimated from the pixel value and the position of each pixel using a ray tracing technique. The light field of a krypton lamp was experimentally measured by the proposed method, and the accuracy of the measurement was evaluated against the irradiances measured by a spectro-radiometer at sample points.     

Instability of traveling waves in an optical waveguide

Instability of traveling IR waves within a waveguide structure is discussed. A practical model of a traveling wave amplifier of a solid state is proposed, utilizing an optical waveguide. The mechanism of instability is interpreted in terms of an interaction between a plasmon wave and a circuit one under a constraining boundary condition. Properties of the traveling amplification and related problems are discussed, with appropriately suggested semiconductor materials and device designs. The features of the amplifier are a simple structure, a low DC biasing power dissipation for room-temperature operation, unidirectionality, and a wide wavelength range from IR or submillimeter order, suited to various applications.     

Unidirectional Single-Mode 532-nm Nd:YAG Laser Using Intracavity Frequency Doubling in Nonplanar Ring Geometry

Intracavity frequency doubling of a single-mode Nd:YAG laser using a nonplanar ring cavity is demonstrated. The nonplanar ring cavity consists of a Brewster-angled Nd: YAG crystal placed in a magnetic field, a KTP crystal, and two spherical mirrors. In this design the Nd:YAG crystal acts as both a nonreciprocal polarization rotator and a partial polarizer, and the nonplanar portion of the ring cavity, which is formed by a relative twist angle between the Brewster-angled end surfaces of the crystal, serves as a reciprocal polarization rotator. Eigenpolarization theory for the cavity configuration is presented and a suitable value of the relative twist angle for unidirectional operation is estimated. A single-mode output power of 22 mW at 532 nm is obtained with a 1.2-W diode laser at 809 nm and a laser linewidth of less than 100 kHz is inferred from a beat note frequency spectrum between two identical laser systems.     

Diachronic quantum action principle

Classical path and action are diachronic concepts in that they refer to many times instead of just one. The concept of a path is quantized into the concept of a propagation process between the initial preparation of and a measurement on a quantum system. A new quantum action is defined as a linear operator on the space of propagation processes, analogously to representing observables as linear operators on the ket and bra spaces. This quantization of paths and action results in a diachronic action principle: a variation of a dynamical propagation process is generated by the associated variation of the quantum action. The form of this principle is a candidate for the form of a dynamical principle of a theory without a classical time parameter.     

Comparisons of predicted steady-state levels in rooms with extended- and local-reaction bounding surfaces

A combined beam-tracing and transfer-matrix model for predicting steady-state sound-pressure levels in rooms with multilayer bounding surfaces was used to compare the effect of extended- and local-reaction surfaces, and the accuracy of the local-reaction approximation. Three rooms—an office, a corridor and a workshop—with one or more multilayer test surfaces were considered. The test surfaces were a single-glass panel, a double-drywall panel, a carpeted floor, a suspended-acoustical ceiling, a double-steel panel, and glass fibre on a hard backing. Each test surface was modeled as of extended or of local reaction. Sound-pressure levels were predicted and compared to determine the significance of the surface-reaction assumption. The main conclusions were that the difference between modeling a room surface as of extended or of local reaction is not significant when the surface is a single plate or a single layer of material (solid or porous) with a hard backing. The difference is significant when the surface consists of multilayers of solid or porous material and includes a layer of fluid with a large thickness relative to the other layers. The results are partially explained by considering the surface-reflection coefficients at the first-reflection angles.     

The Klein-Gordon and the Dirac Oscillators in a Noncommutative Space

We study the Dirac and the Klein-Gordon oscillators in a noncommutative space. It is shown that the Klein-Gordon oscillator in a noncommutative space has a similar behaviour to the dynamics of a particle in a commutative space and in a constant magnetic field. The Dirac oscillator in a noncommutative space has a similar equation to the equation of motion for a relativistic fermion in a commutative space and in a magnetic field, however a new exotic term appears, which implies that a charged fermion in a noncommutative space has an electric dipole moment.     

A Holographic Prism Based on Photo-Thermo-Refractive Glass: Requirements and Possibilities

A technology for multivalued holographic measurement of a plane angle—a holographic prism, which serves as the basis for a device for calibrating the testing tools for navigational equipment under rolling— has been developed. The holographic prism is a miniature sample of photosensitive material, which contains a system of superimposed holographic gratings, and a laser the radiation of which passes through gratings to form a fan of diffracted beams. The fan in a prism based on a calcium fluoride (fluorite) crystal with color centers contained six out-of-plane beams radiating from a region with a hard-to-localize center. This fact hindered calibration of the measure and its application in the testing device. The use of photothermo-refractive glass as a material for preparing a sample and recording a system of holograms in it makes it possible to eliminate the drawbacks of fluorite-based prism. The number of holograms rises up to 21, the fan becomes in-plane, and its center is localized in a small region, with a size of several tenths of the sample thickness (1–2 mm). The fan beams are energetically homogeneous, and each can be identified when using the fan in a testing device.     

单电子在含有双能级原子的空腔中的输运行为

本文构造了一个含有双能级原子的空腔系统,用来模拟一个含有双能级量子点的微腔系统, 并研究其对电子输运行为的影响.通过对该系统输运方程的求解,给出了系统输运系数的具体表达式,然后通过调整空腔及原子的本征特性以及两者的耦合性质,研究了电子在腔体中的输运行为对腔体本征属性的依赖关系. 这些结果可以为如何操控电子在微观结构器件中的输运特性提供一定的理论支持.     

Development of a self-oscillating ultrasonic micro-motor and its application to a watch

We have developed an ultrasonic micro-motor for use as a micro-actuator in place of an electromagnetic motor. This ultrasonic micro-motor, which can be driven by a single signal and in which the change of the direction of the rotor movement can be made easily by selecting the electrode to apply the driving signal, can easily construct a self-oscillating circuit and simplify the driving circuit. We have also simplified the motor structure, which is easy to miniaturize and mass-produce. We applied a version of this motor with a diameter of 8 mm to a vibration alarm, and one with a diameter of 4.5 mm to a driving source of a calendar mechanism in a watch. This ultrasonic micro-motor is expected to be of use as a new driving source in a broad range of fields.     

The analysis of impact forces in randomly vibrating elastic systems

This work is concerned with the characteristics of the impact force produced when two randomly vibrating elastic bodies collide with each other, or when a single randomly vibrating elastic body collides with a stop. The impact condition includes a non-linear spring, which may represent, for example, a Hertzian contact, and in the case of a single body, closed form approximate expressions are derived for the duration and magnitude of the impact force and for the maximum deceleration at the impact point. For the case of two impacting bodies, a set of algebraic equations are derived which can be solved numerically to yield the quantities of interest. The approach is applied to a beam impacting a stop, a plate impacting a stop, and to two impacting beams, and in each case a comparison is made with detailed numerical simulations. Aspects of the statistics of impact velocity are also considered, including the probability that the impact velocity will exceed a specified value within a certain time.     

Atomic quantum gases in Kagomé lattices

We demonstrate the possibility of creating and controlling an ideal and trimerized optical Kagomé lattice, and study the low temperature physics of various atomic gases in such lattices. In the trimerized Kagomé lattice, a Bose gas exhibits a Mott transition with fractional filling factors, whereas a spinless interacting Fermi gas at 2/3 filling behaves as a quantum magnet on a triangular lattice. Finally, a Fermi-Fermi mixture at half-filling for both components represents a frustrated quantum antiferromagnet with a resonating-valence-bond ground state and quantum spin liquid behavior dominated by a continuous spectrum of singlet and triplet excitations. We discuss the method of preparing and observing such a quantum spin liquid employing molecular Bose condensates.     

Direct measurement of group dispersion of optical components using white-light spectral interferometry

We present a simple white-light spectral interferometric technique employing a low-resolution spectrometer for a direct measurement of the group dispersion of optical components over a wide wavelength range. The technique utilizes an unbalanced Mach-Zehnder interferometer with a component under test inserted in one arm and the other arm with adjustable path length. We record a series of spectral interferograms to measure the equalization wavelength as a function of the path length difference. We measure the absolute group refractive index as a function of wavelength for a quartz crystal of known thickness and the relative one for optical fiber. In the latter case we use a microscope objective in front and a lens behind the fiber and subtract their group dispersion, which is measured by a technique of tandem interferometry including also a Michelson interferometer.     

Plasma-assisted deposition of a three-layer structure by vacuum andgas arcs

The durability and adhesion of thin coatings often depends on the structure and properties of the layer intermediate between the coating and the substrate, especially in the case where the layer and the substrate are highly different in microhardness. With a vacuum arc and a hot-cathode arc, a process has been arranged which involves cleaning of the surface, nitration of the article, and deposition of a coating. As a result, a three-layer composition has been produced which consists of a TiN layer of thickness up to 5 μm and microhardness 20 GPa, an intermediate Fe₄N layer of thickness up to 8 μm and microhardness 7.5 GPa, and a nitrated layer of thickness up to 100 μm with a gradually varying microhardness. With the TiN layer showing high adhesion, the coating has a durability three of four times greater than that of a coating produced with the use of a conventional technology     

Scalar density concomitants of a metric and a bivector

We find the most general form of a scalar density concomitant of a metric tensor and a bivector. This, together with previous theorems, gives a complete characterization of the tensor concomitants of a metric and a bivector.     

新型冰箱制冷剂三氟甲醚与异丁烷的性能对比

本文对氟化醚类工质三氟甲醚(简称HFE143a)用作冰箱制冷剂的性能与现有冰箱制冷剂HC600a进行了对比。首先比较了新制冷剂HFE143a和现有冰箱制冷剂CFC12、HFC134a、HC600a和HFC152a/HCFC22等的基础热力性质。然后对HFE143a、HC600a和CFC12的冰箱标准工况制冷循环性能和变工况制冷循环性能进行了详细的理论计算及分析。分析表明:HFE143a完全适合做新一代冰箱制冷剂。     

Letter: Irreversible Processes in a Universe Modelled as a Mixture of a Chaplygin Gas and Radiation

The evolution of a Universe modelled as a mixture of a Chaplygin gas and radiation is determined by taking into account irreversible processes. This mixture could interpolate periods of a radiation dominated, a matter dominated and a cosmological constant dominated Universe. The results of a Universe modelled by this mixture are compared with the results of a mixture whose constituents are radiation and quintessence. Among other results it is shown that: (a) for both models there exists a period of a past deceleration with a present acceleration; (b) the slope of the acceleration of the Universe modelled as a mixture of a Chaplygin gas with radiation is more pronounced than that modelled as a mixture of quintessence and radiation; (c) the energy density of the Chaplygin gas tends to a constant value at earlier times than the energy density of quintessence does; (d) the energy density of radiation for both mixtures coincide and decay more rapidly than the energy densities of the Chaplygin gas and of quintessence.     

具有态守恒赝隙的光子晶体中两能级原子自发辐射的增强与抑制

论证了在赝带隙光子晶体中存在一个全频率域态总数守恒规则，在完全带隙光子晶体中还存在一个局域态总数守恒规则.态总数守恒规则指出，如果一个光子晶体的态密度在某些频率范围存在相对于等效介质态密度的谷，则一定由其他频率范围内相对于等效介质态密度的峰来补偿.使用符合态总数守恒规则的态密度模型，解释了态密度调制导致的自发辐射谱增强、抑制、变窄、红移、蓝移以及谱分裂等光子晶体中的量子光学现象.该理论比较适合研究在具有赝带隙的光子晶体中大量随机分布的发光原子或分子的自发辐射行为. 关键词： 光子晶体 自发辐射 态密度 光子赝带隙