Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627, USA.
Phys Rev Lett. 2013 Mar 29;110(13):130407. doi: 10.1103/PhysRevLett.110.130407. Epub 2013 Mar 27.
In this Letter, we derive an entropic Einstein-Podolsky-Rosen (EPR) steering inequality for continuous-variable systems using only experimentally measured discrete probability distributions and details of the measurement apparatus. We use this inequality to witness EPR steering between the positions and momenta of photon pairs generated in spontaneous parametric down-conversion. We examine the asymmetry between parties in this inequality, and show that this asymmetry can be used to reduce the technical requirements of experimental setups intended to demonstrate the EPR paradox. Furthermore, we develop a more stringent steering inequality that is symmetric between parties, and use it to show that the down-converted photon pairs also exhibit symmetric EPR steering.
在这封信中，我们仅使用实验测量的离散概率分布和测量仪器的细节，推导出连续变量系统的一个熵爱因斯坦-波多尔斯基-罗森（EPR）导引不等式。我们使用这个不等式来见证在自发参量下转换中产生的光子对的位置和动量之间的 EPR 导引。我们检查了这个不等式中双方之间的不对称性，并表明这种不对称性可以用于降低旨在展示 EPR 佯谬的实验设置的技术要求。此外，我们开发了一个更严格的在双方之间对称的导引不等式，并使用它来表明下转换的光子对也表现出对称的 EPR 导引。
