简介:WesuggesttwoschemestogeneratetheWstateofNA-typethree-levelatoms.Intheschemes,identicalNthree-levelatomsaretrappedinacavityorNdistantcavities.ThesuccessorfailureofthegenerationoftheWstatecanbedeterminedbydetectingthepolarizationofphotonleakingoutofthecavity.TheresultdemonstratesthattheWstateisfreefromboththecavitylossandthespontaneousemissionduetothefactthatthetwogroundstates(leftandright)ofthethree-levelatomsarestablestates(ormetastablestates).