The Schrödinger Equation and the Evolution Operator

C M Cheng, P. C. W. Fung

The authors present a method for finding the evolution operator for the Schrodinger equation for the Hamiltonian expressible as H(t)=a 1 (t)J 4 +a 2 (t)J 0 +a 3 (t) J - where J + , J 0 and J - are the SU(2) group generators. Such a method is applied to the disentangling technique for exponential operators which are not necessarily unitary. As a demonstration of our general approach, they solved the problem of a harmonic oscillator with a varying mass.

P. C. Garcia Quijas, L. M. Arévalo Aguilar

Recently, there have been many efforts to use the research techniques developed in the field of physics education research to improve the teaching and learning of quantum mechanics. In particular, part of this research is focusing on misconceptions held by students. For instance, a set of misconceptions is associated with the concept of stationary states. In this paper, we argue that a possible way to remove these is to solve the Schrödinger equation using the evolution operator method (EOM), and stress the fact that to find stationary states is only the first step in solving that equation. The EOM consists in solving the Schrödinger equation by direct integration, i.e. Ψ( x , t ) = U ( t )Ψ( x , 0), where is the time evolution operator, and Ψ( x , 0) is the initial state. We apply the evolution operator method in the case of the harmonic oscillator.

JOHN C. MORRISON

Flip Boer

This paper derives Schrödinger evolution as a structural consequence of coherent persistence rather than as a postulate of quantum mechanics. Starting from minimal requirements for viable propagation—linearity, norm preservation, and continuity—we show that admissible evolution must be unitary and generated by a self-adjoint operator. The resulting Schrödinger equation describes reversible propagation within the space of viable states, while irreversible selection arises separately from the return operation. This separation clarifies the relation between unitary dynamics and measurement without introducing collapse mechanisms or stochastic dynamics. Schrödinger evolution thus emerges as the unique form of continuous, coherence-preserving propagation compatible with structural closure and return, completing the dynamical layer of the Structural Coherence framework.

Pravir Malik