Phys.org June 28, 2018 To realize the strong light-matter interaction that is necessary for all-optical quantum devices, a team of researchers in the US (Harvard University, MIT) used a laser-cooled ensemble of 87Rb atoms (~10 uK) trapped within a high-finesse optical resonator (finesse ~50000) in an ultrahigh-vacuum chamber. To switch a photon with a photon in such a system, they used ‘vacuum-induced transparency’ in which an electromagnetic field as weak as a vacuum field is shown to alter the optical properties of atoms. The research is a step towards deterministic multi-mode entanglement generation as well as high-fidelity photonic quantum gates […]