Observation of the acceleration of light in a tapered optical fiber

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. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

The Unruh effect, a fascinating aspect of quantum fields in curved spacetime, remains a challenge for direct experimental detection of Unruh temperature. Gradient optical waveguides are proposed to achieve high effective Unruh temperature, but experimental realization is yet to be reported. This study uses a tapered fiber to simulate accelerated motion and obtains effective Unruh temperature, showing a dependence of leaky radiation on photon acceleration.