Exploring the transition between Quantum and Classical Mechanics

TL;DR

This paper examines how quantum systems transition to classical behavior by comparing probability distributions derived from both quantum wave packets and classical Gaussian initial conditions, and proposes a method to recover classical distributions from quantum data.

Contribution

It introduces a novel Fourier-based method to extract classical distributions from quantum states, improving understanding of quantum-classical correspondence.

Findings

Quantum probability densities match classical Gaussian distributions for simple cases.

Quantum interference causes deviations in superpositions of Gaussian states.

The proposed Fourier analysis method effectively recovers classical distributions from quantum data.

Abstract

We investigate the transition from quantum to classical mechanics using a one-dimensional free particle model. In the classical analysis, we consider the initial positions and velocities of the particle drawn from Gaussian distributions. Since the final position of the particle depends on these initial conditions, convolving the Gaussian distributions associated with these initial conditions gives us the distribution of the final positions. In the quantum scenario, using an initial Gaussian wave packet, the temporal evolution provides the final wave function, and from it, the quantum probability density. We find that the quantum probability density coincides with the classical normal distribution of the particle's final position obtained from the convolution theorem. However, for superpositions of Gaussian distributions, the classical and quantum results deviate due to quantum interference. To address this issue, we propose a novel approach to recover the classical distribution from the quantum one. This approach involves removing the quantum interference effects through truncated Fourier analysis. These results are consistent with modern quantum decoherence theory. This comprehensive analysis enhances our understanding of the classical-quantum correspondence and the mechanisms underlying the emergence of classicality from quantum systems.