Quantum Simulation of Oscillatory Unruh Effect with Superposed Trajectories

TL;DR

This paper demonstrates a quantum simulation of the Unruh effect using a trapped ion, revealing quantum interference in superposed accelerating trajectories and providing insights into quantum gravity phenomena.

Contribution

It introduces an experimental method to simulate oscillating and superposed quantum trajectories of an accelerating detector, highlighting quantum interference effects related to the Unruh effect.

Findings

Observation of joint excitation of detector and field consistent with Unruh effect

Demonstration of quantum interference in superposed trajectories

Potential pathway for direct experimental observation of the Unruh effect

Abstract

The Unruh effect predicts an astonishing phenomenon that an accelerated detector would detect counts despite being in a quantum field vacuum in the rest frame. Since the required detector acceleration for its direct observation is prohibitively large, recent analog studies on quantum simulation platforms help to reveal various properties of the Unruh effect and explore the not-yet-understood physics of quantum gravity. To further reveal the quantum aspect of the Unruh effect, analogous experimental exploration of the correlation between the detector and the field, and the consequences for coherent quantum trajectories of the detector without classical counterparts, are essential steps but are currently missing. Here, we utilize a laser-controlled trapped ion to experimentally simulate an oscillating detector coupled with a cavity field. We observe joint excitation of both the detector and the field in the detector's frame, coincide with the coordinated dynamics predicted by the Unruh effect. Particularly, we simulate the detector moving in single and superposed quantum trajectories, where the latter case shows coherent interference of excitation. Our demonstration reveals properties of quantum coherent superposition of accelerating trajectories associated with quantum gravity theories that have no classical counterparts, and may offer a new avenue to investigate phenomena in quantum field theory and quantum gravity. We also show how a generalization of the method and results in this work may be beneficial for direct observation of the Unruh effect.