永利总站线路:Gotcha!

 作者:祁队滚     |      日期:2019-03-08 08:16:00
NORMALLY you can’t detect a single photon without destroying it, but Serge Haroche of the Ecole Normale Supérieur in Paris and his colleagues have found a trick that lets them have their cake and eat it. The researchers built a superconducting cavity that can trap a photon for up to a millisecond. The researchers were able to tell if their trap had caught a photon by probing the box with a beam of excited rubidium atoms (Nature, vol 400, p 239). When one of the rubidium atoms absorbs a photon, it re-emits an identical one but slightly changes its quantum properties in the process. By measuring that shift,