Schr\"odinger formalism for a particle constrained to a surface in $\mathbb{R}_1^3$

TL;DR

This paper develops a Schr"odinger equation framework for particles constrained to surfaces in Minkowski space, revealing a geometry-dependent potential influenced by surface curvature and metric signature, with applications to hyperbolic materials.

Contribution

It introduces a consistent Schr"odinger formalism in Minkowski space, incorporating a geometry-induced potential that depends on surface curvature and metric signature, extending quantum surface models.

Findings

Derived a new geometry-induced potential in Minkowski space

Found exact solutions for Schr"odinger equation on specific surfaces

Highlighted potential applications in hyperbolic metamaterials

Abstract

In this work it is studied the Schr\"odinger equation for a non-relativistic particle restricted to move on a surface $S$ in a three-dimensional Minkowskian medium $\mathbb{R}_1^3$, i.e., the space $\mathbb{R}^3$ equipped with the metric $\text{diag}(-1,1,1)$. After establishing the consistency of the interpretative postulates for the new Schr\"odinger equation, namely the conservation of probability and the hermiticity of the new Hamiltonian built out of the Laplacian in $\mathbb{R}_1^3$, we investigate the confining potential formalism in the new effective geometry. Like in the well-known Euclidean case, it is found a geometry-induced potential acting on the dynamics $V_S = - \frac{\hbar^{2}}{2m} \left(\varepsilon H^2-K\right)$ which, besides the usual dependence on the mean ($H$) and Gaussian ($K$) curvatures of the surface, has the remarkable feature of a dependence on the signature of the induced metric of the surface: $\varepsilon= +1$ if the signature is $(-,+)$, and $\varepsilon=1$ if the signature is $(+,+)$. Applications to surfaces of revolution in $\mathbb{R}^3_1$ are examined, and we provide examples where the Schr\"odinger equation is exactly solvable. It is hoped that our formalism will prove useful in the modeling of novel materials such as hyperbolic metamaterials, which are characterized by a hyperbolic dispersion relation, in contrast to the usual spherical (elliptic) dispersion typically found in conventional materials.