Abstract
We report an experimental demonstration of the nonclassical stationary light pulse (SLP) in a cold atomic ensemble. A single collective atomic excitation is created and heralded by detecting a Stokes photon in the spontaneous Raman scattering process. The heralded single atomic excitation is converted into a single stationary optical excitation or the single-photon SLP, whose effective group velocity is zero, effectively forming a trapped single-photon pulse within the cold atomic ensemble. The single-photon SLP is then released from the atomic ensemble as an anti-Stokes photon after a specified trapping time. The second-order correlation measurement between the Stokes and anti-Stokes photons reveals the nonclassical nature of the single-photon SLP. Our work paves the way toward quantum nonlinear optics without a cavity.
- Received 14 December 2017
- Revised 6 March 2018
DOI:https://doi.org/10.1103/PhysRevX.8.021016
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
Published by the American Physical Society
Physics Subject Headings (PhySH)
Popular Summary
Light normally travels at roughly 300,000 km/s, but it can be fully stored in a finely tuned gas of ultracold atoms. When light is stored in an atomic gas, no optical energy remains. An alternate approach known as a stationary light pulse (SLP), however, can retain optical energy even while the light stands still. A SLP could greatly enhance interactions between photons, thus enabling new approaches to quantum computing and quantum optics. The SLP effect could even lead to new and exotic light-based quantum materials, such as a photonic crystal. Despite the fact that applications of SLPs require quantum states of light, all experimental demonstrations to date have been limited to classical light pulses only. Here, we report the first experimental demonstration of a quantum SLP.
In a quantum SLP, a single-photon state is trapped in a cold ensemble of atoms without the help of an optical cavity, such as those used in classical approaches to this problem. Our atomic ensemble consists of 87 rubidium atoms all prepared in the ground state. First, a single collective atomic excitation is prepared in the atomic medium with a laser beam. The single collective atomic excitation is then converted into a single-photon state trapped inside the atomic medium by a pair of counterpropagating trapping laser beams. After a specified trapping time (ranging from 0.6 to ), the trapped single photon is released from the atomic medium by turning off one of the two trapping laser beams.
Our work paves the way toward quantum nonlinear optics without a cavity, as well as novel quantum devices and materials.