title: Quantum state engineering of light with continuous-wave optical parametric oscillators.
abstract: Engineering non-classical states of the electromagnetic field is a central quest for quantum optics(1,2). Beyond their fundamental significance, such states are indeed the resources for implementing various protocols, ranging from enhanced metrology to quantum communication and computing. A variety of devices can be used to generate non-classical states, such as single emitters, light-matter interfaces or non-linear systems(3). We focus here on the use of a continuous-wave optical parametric oscillator(3,4). This system is based on a non-linear χ(2) crystal inserted inside an optical cavity and it is now well-known as a very efficient source of non-classical light, such as single-mode or two-mode squeezed vacuum depending on the crystal phase matching. Squeezed vacuum is a Gaussian state as its quadrature distributions follow a Gaussian statistics. However, it has been shown that number of protocols require non-Gaussian states(5). Generating directly such states is a difficult task and would require strong χ(3) non-linearities. Another procedure, probabilistic but heralded, consists in using a measurement-induced non-linearity via a conditional preparation technique operated on Gaussian states. Here, we detail this generation protocol for two non-Gaussian states, the single-photon state and a superposition of coherent states, using two differently phase-matched parametric oscillators as primary resources. This technique enables achievement of a high fidelity with the targeted state and generation of the state in a well-controlled spatiotemporal mode.
authors: Laboratoire Kastler Brossel, Université Pierre et Marie Curie, Ecole Normale Supérieure, CNRS.
authors: Olivier
authors: O
authors: Morin
authors: Laboratoire Kastler Brossel, Université Pierre et Marie Curie, Ecole Normale Supérieure, CNRS.
authors: Jianli
authors: J
authors: Liu
authors: Laboratoire Kastler Brossel, Université Pierre et Marie Curie, Ecole Normale Supérieure, CNRS; State Key Laboratory of Precision Spectroscopy, East China Normal University.
authors: Kun
authors: K
authors: Huang
authors: Instituto de Física, Universidade de São Paulo.
authors: Felippe
authors: F
authors: Barbosa
authors: Laboratoire Kastler Brossel, Université Pierre et Marie Curie, Ecole Normale Supérieure, CNRS.
authors: Claude
authors: C
authors: Fabre
authors: Laboratoire Kastler Brossel, Université Pierre et Marie Curie, Ecole Normale Supérieure, CNRS; julien.laurat@upmc.fr.
authors: Julien
authors: J
authors: Laurat
mesh_terms: D008027:Light; D009991:Oscillometry / Q000295:instrumentation / Q000379:methods*; D017785:Photons; D011789:Quantum Theory