# Space QUEST mission proposal: Experimentally testing decoherence due to gravity

## TL;DR

This paper proposes a space-based experiment to test whether gravity causes decoherence in quantum entanglement, aiming to verify or challenge theories predicting gravity-induced quantum effects.

## Contribution

It introduces a detailed mission design for ESA's Space QUEST to experimentally test gravitational decoherence of entanglement in space.

## Key findings

- Feasibility analysis of the Space QUEST mission.
- Extension of theoretical models predicting gravitational decoherence.
- Discussion of scientific implications of detecting or not detecting decoherence.

## Abstract

Models of quantum systems on curved space-times lack sufficient experimental verification. Some speculative theories suggest that quantum properties, such as entanglement, may exhibit entirely different behavior to purely classical systems. By measuring this effect or lack thereof, we can test the hypotheses behind several such models. For instance, as predicted by Ralph and coworkers [T C Ralph, G J Milburn, and T Downes, Phys. Rev. A, 79(2):22121, 2009, T C Ralph and J Pienaar, New Journal of Physics, 16(8):85008, 2014], a bipartite entangled system could decohere if each particle traversed through a different gravitational field gradient. We propose to study this effect in a ground to space uplink scenario. We extend the above theoretical predictions of Ralph and coworkers and discuss the scientific consequences of detecting/failing to detect the predicted gravitational decoherence. We present a detailed mission design of the European Space Agency's (ESA) Space QUEST (Space - Quantum Entanglement Space Test) mission, and study the feasibility of the mission schema.