Observation of the acceleration of light in a tapered optical fiber

TL;DR

This paper demonstrates the observation of effective Unruh temperature by using a tapered optical fiber to simulate accelerated motion of photons, revealing leaky radiation patterns dependent on acceleration.

Contribution

It introduces a novel experimental setup using tapered fibers to simulate photon acceleration and observe Unruh temperature effects.

Findings

Leaky radiation pattern varies with photon acceleration.

Different accelerations produce distinct Unruh temperatures.

Experimental validation of simulated acceleration effects in optical fibers.

Abstract

One of the most fascinating aspects of quantum fields in curved spacetime is the Unruh effect. The direct experimental detection of Unruh temperature has remained an elusive challenge up to now. Gradient optical waveguides manipulating the dispersion of photons are assumed to realize the great acceleration of effective particles, leading to a high effective Unruh temperature. However, experimentally achieving this optical waveguide has not yet been reported. In this work, we exploit a tapered fiber to simulate the accelerated motion of effective particles and obtain an effective Unruh temperature. When light propagating in a tapered fiber is affected by the external high refractive index medium, a leaky phenomenon akin to bremsstrahlung will be observed, and the pattern of leaky radiation is dependent on the acceleration of photons. During the experiments, different accelerations corresponding to different Unruh temperatures are achieved by controlling the shape of the tapered waveguide.