Natural disorder distributions from measurement

TL;DR

This paper explores how local measurements on environmental degrees of freedom induce complex, non-Gaussian disorder distributions in quantum system dynamics, with potential applications in laboratory and cosmological contexts.

Contribution

It introduces a framework for understanding measurement-induced disorder with non-Gaussian distributions using anharmonic oscillators and derives their properties for various measurements.

Findings

Distributions are generally non-Gaussian and spacetime-varying.

Measurement-induced disorder can be realized in laboratory quantum systems.

The approach extends to scenarios relevant in particle physics and cosmology.

Abstract

We consider scenarios where the dynamics of a quantum system are partially determined by prior local measurements of some interacting environmental degrees of freedom. The resulting effective system dynamics are described by a disordered Hamiltonian, with spacetime-varying parameter values drawn from distributions that are generically neither flat nor Gaussian. This class of scenarios is a natural extension of those where a fully non-dynamical environmental degree of freedom determines a universal coupling constant for the system. Using a family of quasi-exactly solvable anharmonic oscillators, we consider environmental ground states of nonlinearly coupled degrees of freedom, unrestricted by a weak coupling expansion, which include strongly quantum non-Gaussian states. We derive the properties of distributions for both quadrature and photon number measurements. Measurement-induced disorder of this kind is likely realizable in laboratory quantum systems and, given a notion of naturally occurring measurement, suggests a new class of scenarios for the dynamics of quantum systems in particle physics and cosmology.