Morin Olivier, Liu Jianli, Huang Kun, Barbosa Felippe, Fabre Claude, Laurat Julien
Laboratoire Kastler Brossel, Université Pierre et Marie Curie, Ecole Normale Supérieure, CNRS.
Laboratoire Kastler Brossel, Université Pierre et Marie Curie, Ecole Normale Supérieure, CNRS; State Key Laboratory of Precision Spectroscopy, East China Normal University.
J Vis Exp. 2014 May 30(87):51224. doi: 10.3791/51224.
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.
操控电磁场的非经典态是量子光学的核心研究目标(1,2)。除了其基本意义外，这些态实际上是实现各种协议的资源，涵盖从增强计量学到量子通信和计算等领域。可以使用多种设备来生成非经典态，例如单发射器、光与物质的界面或非线性系统(3)。我们在此关注连续波光参量振荡器的应用(3,4)。该系统基于置于光学腔内的非线性χ(2)晶体，如今它作为一种非常高效的非经典光源而广为人知，根据晶体的相位匹配情况可产生单模或双模压缩真空等。压缩真空是一种高斯态，因为其正交分布遵循高斯统计。然而，已经表明许多协议需要非高斯态(5)。直接生成此类态是一项艰巨的任务，并且需要很强的χ(3)非线性。另一种方法虽然具有概率性但有 heralded（这个词有误，可能是heralded，意为有预兆的、被预示的），是通过对高斯态进行条件制备技术利用测量诱导的非线性。在此，我们详细介绍使用两个相位匹配不同的参量振荡器作为主要资源来生成两个非高斯态（单光子态和相干态叠加）的协议。该技术能够实现与目标态的高保真度，并以良好控制的时空模式生成该态。
