Gravitational waves decohere quantum superpositions

TL;DR

This paper investigates how gravitational waves, especially their memory effects, cause decoherence in quantum superpositions, highlighting the dominant role of memory contributions over oscillatory components.

Contribution

It identifies and analyzes the specific roles of memory and oscillatory components of gravitational waves in quantum decoherence, advancing understanding of quantum-gravity interactions.

Findings

Memory effects dominate decoherence from gravitational waves.

Oscillatory components' impact depends on the burst phase.

Quantum coherence loss can be caused by classical gravitational fields.

Abstract

Understanding the interplay between quantum mechanical systems and gravity is a crucial step towards unifying these two fundamental ideas. Recent theoretical developments have explored how global properties of spacetime would cause a quantum spatial superposition to lose coherence. In particular, this loss of coherence is closely related to the memory effect, which is a prominent feature of gravitational radiation. In this work, we explore how a burst of gravitational radiation from a far-away source would decohere a quantum superposition. We identify the individual contributions to the decoherence from the memory and oscillatory components of the gravitational wave source, corresponding to soft and hard graviton emissions, respectively. In general, the memory contributions dominate, while the oscillatory component of the decoherence is strongly dependent on the phase of the burst when it is switched off. This work demonstrates how quantum systems can lose coherence from interactions with a classical gravitational field. We also comment on the electromagnetic analogue of this effect and discuss its correspondence to the gravitational case.