报告人：Vincent Boyer 副教授
单位：University of Birmingham英国伯明翰大学
主持人：荆杰泰 教授
时间：2022年10月12日（周三）下午17：00
地点：光学大楼B325会议室
ZOOM会议 ID：814 9407 9434，密码：123456
参会链接：https://us06web.zoom.us/j/81494079434?pwd=QWFGLzRqMnIxZ0xicXZTNjVSSEs0UT09
报告人简介：
Vincent did his PhD on Bose-Einstein condensation in Orsay (Paris) and carried on in the field of ultracold atoms first at NIST, then at the University of Oxford. Upon returning to NIST, he switched to quantum optics and contributed to the development of squeezed light generation with hot atomic vapours. He is now at the University of Birmingham, UK, where he splits his research time between quantum optics, quantum simulations with cold atoms, super-resolved microscopy and interferometry for searches of dark matter.
报告内容简介：
Four-wave mixing in atomic vapour is an efficient way to generate twin beams, that is to say beams of light that share quantum fluctuations. Thanks to the large non-linearity, the process is efficient over a large collection of spatial modes, leading to beams that are entangled in matched sub-regions. This opens the prospect of using squeezed or entangled light to improve imaging in general.
In practice the minimum size of the entangled regions is typically given by the diffraction limit and the phase-matching condition. All this is rather well understood when the non-linear medium is thin but things get more complicated when propagation effects in a thick medium have to be taken into account. In this case there is a competition between the fact that correlations between twin beams are created locally, and the fact that the conservation of momentum pulls the correlated photons apart.
I will review the process of four-wave mixing in atomic vapours, show that spatial correlations propagates in the gain medium in lockstep, and explain how this leads to a complex spatial entanglement geometry at the end of the medium. I will also present experimental evidence of the effect and our effort to directly measure the squeezing spatial structure of squeezed beams.