Wave Packet under Continuous Measurement via Bohmian Mechanics

TL;DR

This paper introduces a Bohmian mechanics-based approach to describe wave packet dynamics under continuous measurement, revealing both chaotic and non-chaotic behaviors and potential to surpass quantum limits.

Contribution

It presents a novel wave packet approach within Bohmian mechanics that clarifies wave packet dynamics under continuous measurement, linking classical chaos with quantum phenomena.

Findings

Wave packet exhibits both chaotic and non-chaotic features.

Lyapunov exponents for classical and quantum trajectories are similar.

Wave packet width can transiently contract, surpassing the standard quantum limit.

Abstract

A new quantum mechanical description of the dynamics of wave packet under continuous measurement is formulated via Bohmian mechanics. The solution to this equation is found through a wave packet approach which establishes a direct correlation between a classical variable with a quantum variable describing the dynamics of the center of mass and the width of the wave packet. The approach presented in this paper gives a comparatively clearer picture than approaches using restrited path integrals and master equation approaches. This work shows how the extremely irregular character of classical chaos can be reconciled with the smooth and wavelike nature of phenomena on the atomic scale. It is demonstrated that a wave packet under continuous quantum measurement displays both chaotic and non-chaotic features. The Lyapunov characteristic exponents for the trajectories of classical particle and the quantum wave packet center of mass are calculated and their chaoticities are demonstrated to be about the same. Nonetheless, the width of the wave packet exhibits a non-chaotic behavior and allows for the possibility to beat the standard quantum limit by means of transient, contractive states.