This paper draws a comparison between atom optics and light optics, based on the observation that one can derive a Schrödinger equation for the slowly varying amplitude of the electromagnetic field in the paraxial approximation, the `optical Schrödinger equation'. A correction scheme between (monochromatic) light waves and matter waves is established and applied to cases of interest in atom or fibre optics. First the propagation in a periodic -potential is investigated, where well known effects, such as Bragg scattering or channelling are re-examined from a `matter wave versus light wave' point of view. In a second application the general theory is extended to axisymmetrical materials such as step-index fibres or graded-index fibres. In particular, a matter wave analogue of the so-called non-diffractive beams of electrodynamics is discussed.
The scalar wave equation is analyzed in the relativistic front form, appropriate for paraxial-wave optics. The group-theoretical basis for this treatment is uncovered. The formal similarity of the propagation of paraxial beams through optical systems to the quantum mechanics of particles in two dimensions subject to harmonic impulses, and the role of the metaplectic group of Bacry and Cadilhac, are both traced back to the structure of the Poincar\'e group. Light rays are defined in this context as in statistical-wave optics, and the laws for their free propagation as well as transmission through lenses are derived.
The aim of this work is to study how losses modify quantum effects in a system governed by the spatial nonlinear Schrodinger equation. Quantum effects in space, such as quantum noise, squeezing, and bunching, have been studied in a lossless case.1 We will consider the propagation of a field through a planar nonlinear waveguide,2,3 where confinement is provided in one transverse dimension (y direction) by a linear refractive index and in the orthogonal dimension (x direction) by the intensity dependence of the refractive index.1,4 Attenuation is given to the spatial distribution in the x-z plane. In this work we want to extend the dissipation approach described in Ref. 5 to a system governed by the spatiai-nonlinear Sclirodinger equation (SNLS). We use a quantum-field description1 in which the spatial variable of propagation z plays the role of the time in the standard quantum theory, and we apply it to the case of a strong plane wave that can be described as a classical field propagating through a nonlinear waveguide in the z direction.4 By using both paraxial and slowly-varying-envelope approximations, the propagation of the field in a planar waveguide is described by the NLS.1
Abstract The similarity between the Schrödinger equation and the paraxial wave equation permits numerous analogies linking these fields, which is pivotal in advancing both quantum mechanics and wave optics. In this study, we demonstrate the application of operator techniques to an electromagnetic field characterized by the function f(x + ay), leveraging the structural analogies between these equations. Specifically, we employ initial conditions defined by Airy and Bessel functions to illustrate the practical implementation of these techniques.
The classical concept of a paraxial wave is extended to quantum optics as a condition on the state vector, and the family of vectors obeying this condition defines a paraxial Hilbert space. Field operators acting on this space are approximated by the product of a slowly-varying envelope operator and a classical carrier wave. This permits the discussion of Gaussian pulses and paraxial wave packets. This treatment is extended to obtain an expansion of state vectors and field operators in powers of the opening angle of the cone of paraxial rays. The leading term in the expansion yields the component of the angular momentum along the propagation axis as a sum of well defined orbital- and spin-parts. With the same technique, it is shown that approximate localization of photons is possible for localization volumes much larger that the mean wavelength in the paraxial state.
Wave mechanics, geometrical optics, classical Hamilton--Jacobi dynamics, electron optics, and gauge-coupled quantum mechanics are usually introduced as conceptually distinct frameworks. Yet they share a common mathematical structure: an environment modifies a local phase relation, the phase defines a local propagation momentum, and the resulting momentum field determines characteristic curves along which propagation occurs. This paper develops a propagation-first synthesis of these structures for particles with nonzero rest mass. For a nonrelativistic spinless particle with wave function
Ψ(r,t)=R(r,t)eiS(r,t)/ℏ,the Schrödinger equation in scalar and electromagnetic potentials is exactly equivalent, wherever the amplitude is sufficiently regular, to a continuity equation and a quantum Hamilton--Jacobi equation,
∂t∂R2+∇⋅[R2m∇S−qA]=0,∂t∂S+2m(∇S−qA)2+qϕ+U+Q=0,where
Q=−2mℏ2R∇2R. The gauge-invariant kinetic propagation momentum is therefore
Π=∇S−qA,and the associated local propagation velocity is
v=mΠ. We call this coupled amplitude--phase representation the \textbf{Unified Propagation System}. The name denotes an organizational framework rather than a new fundamental equation. Within this framework, external interactions can be interpreted as modifications of a local phase--dispersion structure. For static scalar potentials, spatial variation of the local propagation momentum defines an effective matter-wave refractive index and reproduces the optical--mechanical analogy familiar from Hamiltonian and electron optics. Electromagnetic vector potentials generalize this picture: they enter directly into the gauge-invariant phase gradient and therefore modify propagation direction in a manner that cannot in general be represented by a scalar refractive index. This motivates a generalized definition of refraction: \textbf{refraction is the bending of propagation characteristics caused by spatial or temporal variation of the local phase--dispersion relation}. In the semiclassical limit this definition reduces directly to geometrical ray bending. Beyond that limit, the full amplitude-dependent term
Q provides an additional modification of the propagation structure. The same equations can be written in a second-order form,
mdtdv=q(E+v×B)−∇U−∇Q,showing that force-based and propagation-based descriptions can represent the same dynamics at different levels. We therefore propose that electromagnetic deflection, potential scattering, and matter-wave refraction may be regarded as different manifestations of a common propagation principle rather than as fundamentally unrelated mechanisms. The paper deliberately avoids a deeper ontological claim. It does not assert that the wave function, electromagnetic field, and particle arise from a common physical substrate. It instead identifies the propagation structure that any such deeper account would have to reproduce. A relativistic extension based on the gauge-covariant Hamilton--Jacobi equation suggests that the same architecture survives beyond the nonrelativistic Schrödinger regime.