Superposition principle

About: Superposition principle is a research topic. Over the lifetime, 10750 publications have been published within this topic receiving 175964 citations.

Computer modeling and the design of optimal underwater imaging systems

Abstract: A computer model to simulate the formation of underwater images has been developed. The model incorporates the inherent and apparent properties of the propagation of light in water. An image is approximated as a linear superposition of several image components. The model has been used to simulate the relative advantages of different camera/light configurations. The results indicate that extremely large gains in image contrast can be obtained by careful design of beam patterns and the manipulation of camera and light locations. The performance of range-gated systems is explored, and it is demonstrated that these systems are presently power limited. In order to obtain better quality images at larger distances, an imaging configuration which consists of scanning an incoherent light beam across the field of view of a camera is proposed. The incoherent light-scanning system is shown to have advantages over both conventional imaging techniques and range-gated methods. >

Near-Field Interference for the Unidirectional Excitation of Electromagnetic Guided Modes

Abstract: Wave interference is a fundamental manifestation of the superposition principle with numerous applications. Although in conventional optics, interference occurs between waves undergoing different phase advances during propagation, we show that the vectorial structure of the near field of an emitter is essential for controlling its radiation as it interferes with itself on interaction with a mediating object. We demonstrate that the near-field interference of a circularly polarized dipole results in the unidirectional excitation of guided electromagnetic modes in the near field, with no preferred far-field radiation direction. By mimicking the dipole with a single illuminated slit in a gold film, we measured unidirectional surface-plasmon excitation in a spatially symmetric structure. The surface wave direction is switchable with the polarization.

Quantum computation with optical coherent states

Abstract: We show that quantum computation circuits using coherent states as the logical qubits can be constructed from simple linear networks, conditional photon measurements, and "small" coherent superposition resource states.

Transient Radiation from Pistons in an Infinite Planar Baffle

Abstract: An approach is presented to compute the near‐ and farfield transient radiation resulting from a specified velocity motion of a piston or array of pistons in a rigid infinite baffle. The approach, which is based on a Green's function development, utilizes a transformation of coordinates to simplify the evaluation of the resultant surface integrals. A simple expression is developed for an impulse response function, which is the time‐dependent velocity potential at a spatial point resulting from an impulse velocity of a piston of any shape. The time‐dependent velocity potential and pressure for any piston velocity motion may then be computed by a convolution of the piston velocity with the appropriate impulse response. The response of an array may be computed using superposition. Several examples illustrating the usefulness of the approach are presented. The farfield time‐dependent radiation from a rectangular piston is discussed for both continuous and pulsed velocity conditions. For a pulsed velocity of time duration T it is shown that the pressure at several of the field points can consist of two separate pulses of the same duration, when T is less than the travel time across the piston.

Frequency Analysis of Variable Networks

Abstract: This paper describes an approach to the analysis of linear variable networks which is essentially an extension of the frequency analysis techniques commonly used in connection with fixed networks. It is shown that a function H(jω; t), termed the system function of a variable network, possesses most of the fundamental properties of the system function of a fixed network. Thus, once H(jω; t) has been determined, the response to any given input can be obtained by treating H(jω; t) as if it were the system function of a fixed network. It is further shown that H(jω; t) satisfies a linear differential equation in t, which has complex coefficients and is for the same order as the differential equation relating the input and the output of the network. Two methods of solution of this equation covering most cases of practical interest are given. In addition to H(jω; t), a network function introduced is the bi-frequency system function Γ(jω; ju) which is shown to relate the Fourier transforms of the input and the output through a superposition integral in the frequency domain. On the basis of the results obtained in this paper it appears that the frequency domain approach using H(jω; t) possesses significant advantages over the conventional approach using the impulsive response of the network.